Diesel Particulate Matter Exposure of Underground Metal and Nonmetal
Miners; Proposed Rule [08/14/2003]
Volume 68, Number 157, Page 48667-48721
[[Page 48667]]
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Part II
Department of Labor
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Mine Safety and Health Administration
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30 CFR Part 57
Diesel Particulate Matter Exposure of Underground Metal and Nonmetal
Miners; Proposed Rule
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DEPARTMENT OF LABOR
Mine Safety and Health Administration
30 CFR Part 57
RIN 1219-AB29
Diesel Particulate Matter Exposure of Underground Metal and
Nonmetal Miners
AGENCY: Mine Safety and Health Administration (MSHA), Labor.
ACTION: Proposed rule; notice of public hearings; close of comment
period; request for data.
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SUMMARY: This proposed rule would: Revise the existing diesel
particulate matter (DPM) interim concentration limit measured by total
carbon (TC) to a comparable permissible exposure limit (PEL) measured
by elemental carbon (EC) which renders a more accurate DPM exposure
measurement; increase flexibility of compliance by requiring MSHA's
longstanding hierarchy of controls for its other exposure-based health
standards at metal and nonmetal mines, but prohibit rotation of miners
for compliance; allow MSHA to consider economic as well as
technological feasibility in determining if operators qualify for an
extension of time in which to meet the DPM limits; and simplify
requirements for a DPM control plan. The proposed rule would also make
conforming changes to existing provisions concerning compliance
determinations, environmental monitoring and recordkeeping.
The existing final rule pertaining to ``Diesel Particular Matter
Exposure of Underground Metal and Nonmetal Miners,'' was published in
the Federal Register on January 19, 2001 (66 FR 5706, RIN 1219-AB11)
and amended on February 27, 2002 (67 FR 9180). This rulemaking is part
of a settlement agreement reached in response to a legal challenge to
the January 19, 2001 diesel particular matter (DPM) standard.
Specifically in this proposal, MSHA intends to revise existing
Sec. 57.5060(a), limit on concentration of DPM; including designating
elemental carbon as an appropriate surrogate for measuring the interim
DPM limit; Sec. 57.5060(c), addressing application and approval
requirements for an extension of time in which to reduce the
concentration of DPM; Sec. 57.5060(d), addressing certain exceptions
to the concentration limits; Sec. 57.5060(e), prohibiting use of
personal protective equipment to comply with the concentration limits;
Sec. 57.5060(f) prohibiting use of administrative controls to comply
with the concentration limits, and Sec. 57.5062, addressing the diesel
particulate control plan. Also, MSHA intends to make conforming changes
in this rulemaking to existing Sec. 57.5061, addressing compliance
determinations; Sec. 57.5071, addressing exposure monitoring; and
Sec. 57.5075, addressing recordkeeping requirements.
MSHA has incorporated into the record of this rulemaking the
existing rulemaking record, including the risk assessment to the
January 19, 2001 standard. Commenters are encouraged to submit
additional evidence of new scientific data related to the health risk
to underground metal and nonmetal miners from exposure to DPM.
MSHA encourages mine operators to submit information in response to
these provisions, including their current experiences with controlling
miners' exposures to DPM.
In addition, under the terms of the settlement agreement, MSHA
agreed to propose to change the existing DPM surrogate from total
carbon to elemental carbon for both the interim DPM limit currently in
effect and the final DPM limit that is applicable after January 19,
2006. In the Agency's Advance Notice of Proposed Rulemaking published
on September 25, 2002 (67 FR 60199), MSHA notified the mining community
that this rulemaking would revise both the interim concentration limit
of 400 micrograms per cubic meter of air and the final concentration
limit of 160 micrograms per cubic meter of air under Sec. 57.5060 (a)
and (b) of the existing standard. Some commenters to the ANPRM
recommended that MSHA propose separate rulemakings for revising the
interim and final DPM limits to give MSHA an opportunity to gather
further information to establish a final DPM limit. The Agency agrees,
and solicits information that would lead to an appropriate final DPM
standard. The Agency will propose a separate rulemaking to amend the
existing final concentration limit in the near future. With regard to
the final DPM limit of 160 micrograms, MSHA requests comments on an
appropriate final DPM limit.
DATES: All comments on the proposed rule, including post-hearing
comments, must be received by October 14, 2003. The public hearing
dates and locations are listed in the Public Hearings section under
SUPPLEMENTARY INFORMATION. Individuals or organizations wishing to make
oral presentations for the record should submit a request at least 5
days prior to the hearing dates.
ADDRESSES: Comments must be clearly identified as such and may be
transmitted electronically to comments@msha.gov, by facsimile to (202)
693-9441, or by regular mail or hand delivery to MSHA, Office of
Standards, Regulations, and Variances, 1100 Wilson Blvd., Room 2313,
Arlington, Virginia 22209-3939. We intend to post comments on our
website shortly after they are received.
Information Collection Requirements: Comments concerning
information collection requirements must be clearly identified as such
and sent to both MSHA and the Office of Management and Budget (OMB) as
follows:
(1) Send information collection comments to MSHA at the addresses
above.
(2) Send comments to OMB by regular mail addressed to the Office of
Information and Regulatory Affairs, Office of Management and Budget,
New Executive Office Building, 725 17th Street, NW., Washington, DC
20503, Attn: Desk Officer for MSHA.
FOR FURTHER INFORMATION CONTACT: Marvin W. Nichols, Jr., Director,
Office of Standards, Regulations, and Variances, MSHA, 1100 Wilson
Blvd., Room 2313, Arlington, Virginia 22209-3939, Nichols-
Marvin@msha.gov, (202) 693-9440 (telephone), or (202) 693-9441
(facsimile).
You can access this proposed rule and the Preliminary Regulatory
Economic Analysis (PREA) at http://www.msha.gov. You can obtain these
documents in alternative formats, such as large print and electronic
files, by contacting MSHA.
SUPPLEMENTARY INFORMATION:
I. Public Hearings
The public hearings will begin at 9 a.m. and will end after the
last scheduled speaker testifies. The hearings will be held on the
following dates at the locations indicated:
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Date Location Telephone
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September 16, 2003.............. University Park (801) 581-1000
Marriott, 480
Wakara Way, Salt
Lake City, UT
84108.
[[Page 48669]]
September 18, 2003.............. Renaissance St. (314) 429-1100
Louis Hotel
Airport, 9801
Natural Bridge
Road, St. Louis,
MO 63134.
September 23, 2003.............. Hilton Pittsburgh, (412) 391-4600
600 Commonwealth
Place, Pittsburgh,
PA 15222.
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The hearings will begin with an opening statement from MSHA,
followed by an opportunity for members of the public to make oral
presentations. You do not have to make a written request to speak.
Speakers will speak in the order that they sign in. Any unallotted time
will be made available for persons making same-day requests. At the
discretion of the presiding official, the time allocated to speakers
for their presentation may be limited. Speakers and other attendees may
also present information to the MSHA panel for inclusion in the
rulemaking record.
The hearings will be conducted in an informal manner. The hearing
panel may ask questions of speakers. Although formal rules of evidence
or cross examination will not apply, the presiding official may
exercise discretion to ensure the orderly progress of the hearing and
may exclude irrelevant or unduly repetitious material and questions.
A verbatim transcript of the proceedings will be included in the
rulemaking record. Copies of this transcript will be available to the
public, and can be viewed at http://www.msha.gov.
MSHA will accept post-hearing written comments and other
appropriate data for the record from any interested party, including
those not presenting oral statements, prior to the close of the comment
period on October 7, 2003.
II. Background
On January 19, 2001, MSHA published a final rule addressing diesel
particulate matter exposure in underground metal and nonmetal mines (66
FR 5706, amended on February 27, 2002 at 67 FR 9180). The final rule
established new health standards for underground metal and nonmetal
mines that use equipment powered by diesel engines. The effective date
of the rule was listed as March 20, 2001. On January 29, 2001,
AngloGold (Jerritt Canyon) Corp. and Kennecott Greens Creek Mining
Company filed a petition for review of the final rule in the District
of Columbia Circuit Court of Appeals. On February 7, 2001, the Georgia
Mining Association, the National Mining Association, the Salt
Institute, and the Methane Awareness Resource Group (MARG) Diesel
Coalition filed a similar petition in the Eleventh Circuit. On March
14, 2001, Getchell Gold Corporation petitioned for review of the rule
in the District of Columbia Circuit. The three petitions were
consolidated and are pending in the District of Columbia Circuit. The
United Steelworkers of America (USWA) intervened in the litigation.
While these challenges were pending, the AngloGold petitioners
filed with MSHA an application for reconsideration and amendment of the
final rule and to postpone the effective date of the final rule pending
judicial review. The Georgia Mining petitioners similarly filed with
MSHA a request for an administrative stay or postponement of the
effective date of the rule. On March 15, 2001, MSHA delayed the
effective date of the rule until May 21, 2001, in accordance with a
January 20, 2001 memorandum from the President's Chief of Staff (66 FR
15032). The delay was necessary to give Department of Labor officials
the opportunity for further review and consideration of new
regulations. On May 21, 2001 (66 FR 27863), MSHA published a notice in
the Federal Register delaying the effective date of the final rule
until July 5, 2001. The purpose of this delay was to allow the
Department of Labor the opportunity to engage in further negotiations
to settle the legal challenges to this rule.
First Partial Settlement Agreement
As a result of a partial settlement agreement with the litigants,
MSHA published two documents in the Federal Register on July 5, 2001
addressing the January 19, 2001 DPM rule. One document (66 FR 35518)
delayed the effective date of Sec. 57.5066(b) regarding the tagging
provision of the maintenance standard; clarified the effective dates of
certain provisions of the final rule; and included correction
amendments.
The second document (67 FR 35521) proposed a rule to clarify
Sec. Sec. 57.5066(b)(1) and (b)(2) regarding maintenance and to add a
new subparagraph (b)(3) to Sec. 57.5067 regarding the transfer of
existing equipment between underground mines. MSHA published these
changes as a final rule on February 27, 2002 (67 FR 9180), with an
effective date of March 29, 2002.
Under the first partial settlement agreement, MSHA also conducted
joint sampling with industry and labor at 31 underground metal and
nonmetal mines to determine existing concentration levels of DPM; to
assess the performance of the SKC submicron dust sampler with the NIOSH
Method 5040; to assess the feasibility of achieving compliance with the
standard's concentration limits at the 31 mines; and to assess the
impact of interferences on samples collected in the metal and nonmetal
underground mining environment before the limits established in the
final rule become effective. The final report was issued on January 6,
2003.
Second Partial Settlement Agreement
Settlement negotiations continued on the remaining unresolved
issues in the litigation. On July 15, 2002, the parties signed an
agreement that is the basis for this proposed rule. On July 18, 2002,
MSHA published a notice in the Federal Register (67 FR 47296)
announcing that the following provisions of the January 19, 2001 rule
would become effective on July 20, 2002:
(a) Sec. 57.5060(a), addressing the interim concentration limit of
400 micrograms of total carbon per cubic meter of air;
(b) Sec. 57.5061, compliance determinations; and
(c) Sec. 57.5071, environmental monitoring.
The notice also announced that the following provisions of the rule
would continue in effect:
(a) Sec. 57.5065, Fueling practices;
(b) Sec. 57.5066, Maintenance standards;
(c) Sec. 57.5067, Engines;
(d) Sec. 57.5070, Miner training; and
(e) Sec. 57.5075, Diesel particulate records, as they relate to
the requirements of the rule that are in effect on July 20, 2002.
The notice also stayed the effectiveness of the following
provisions pending completion of rulemaking:
(a) Sec. 57.5060(d), permitting miners to work in areas where the
level of diesel particulate matter exceeds the applicable concentration
limit with advance approval from the Secretary;
(b) Sec. 57.5060(e), prohibiting the use of personal protective
equipment to comply with the concentration limits;
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(c) Sec. 57.5060(f) prohibiting the use of administrative controls
to comply with the concentration limits; and
(d) Sec. 57.5062, DPM control plan.
Finally, the notice outlined the terms of the DPM settlement
agreement and announced MSHA's intent to propose specific changes to
the rule, as discussed below.
On September 25, 2002, MSHA published an Advance Notice of Proposed
Rulemaking (67 FR 60199) to revise the DPM rule. The comment period
closed on November 25, 2002. MSHA received comments from underground
metal and nonmetal mine operators, trade associations, organized labor,
individual mine operators, public interest groups and individuals. A
number of commenters from industry and labor requested that MSHA
propose the final DPM limit at a later date to allow MSHA to obtain
more data. Commenters suggested that the Agency needs to determine the
efficiency of different filtration devices, the relationship between
elemental carbon and total carbon, and the feasibility of a DPM
exposure limit.
This proposed rule would revise existing Sec. 57.5060(a),
addressing the interim concentration limit for DPM and the surrogate
for measuring DPM limit; Sec. 57.5060(c), addressing application and
approval requirements for an extension of time in which to reduce the
concentration of DPM; Sec. 57.5060(d), addressing certain exceptions
to the concentration limit; Sec. 57.5060(e), prohibiting use of
personal protective equipment to comply with the concentration limits;
Sec. 57.5060(f) prohibiting use of administrative controls to comply
with the concentration limits, and Sec. 57.5062, addressing the diesel
particulate control plan. MSHA is also proposing conforming changes to
existing Sec. 57.5061, addressing compliance determinations; Sec.
57.5071, addressing exposure monitoring; and Sec. 57.5075, addressing
recordkeeping requirements.
MSHA solicits comments on these provisions, as well as on
experiences with controlling miners' exposures to DPM. MSHA also
encourages commenters to submit additional evidence or new scientific
data related to the health risk of DPM exposure in underground metal
and nonmetal mines.
III. The Final PEL
MSHA intends to propose a revision to the final DPM limit in Sec.
57.5060(b) that would reflect an appropriate permissible exposure limit
rather than a concentration limit and would change the surrogate from
total carbon to elemental carbon. Although the final limit is not a
part of this proposed rule, MSHA solicits comments on an appropriate
final DPM limit.
IV. Executive Summary of the 31-Mine Study
The following is the executive summary from ``MSHA's Report on Data
Collected During a Joint MSHA/Industry Study of DPM Levels in
Underground Metal And Nonmetal Mines'' (31-Mine Study) signed by MSHA
on January 6, 2003. The Preliminary Regulatory Economic Analysis (PREA)
for this proposed rule is not based on the 31-Mine Study.
On January 19, 2001, MSHA published a final standard on exposure
of underground metal and nonmetal miners to diesel particulate
matter (DPM). The rule was to become effective 60 days later,
however, prior to the effective date, the rule was challenged by
industry trade associations and mining companies. The United
Steelworkers of America (USWA) also intervened in the litigation. In
June 2001, agreement was reached on some of the issues in dispute.
The parties further agreed to conduct a study involving joint in-
mine DPM sampling to determine existing concentration levels of DPM
in operating mines and to measure DPM levels in the presence of
known or suspected interferences. The goals of the study were to use
the sampling results and related information to assess:
--The validity, precision and feasibility of the sampling and
analysis method specified by the diesel standard (NIOSH Method
5040);
--The magnitude of interferences that occur when conducting
enforcement sampling for total carbon as a surrogate for diesel
particulate matter (DPM) in mining environments; and
--The technological and economic feasibility of the underground
metal and nonmetal (MNM) mine operators to achieve compliance with
the interim and final DPM concentration limits.
The parties developed a joint MSHA/Industry study protocol to
guide sampling and analysis of DPM levels in 31 mines. The parties
also developed four subprotocols to guide investigations of the
known or suspected interferences, which included mineral dust, drill
oil mist, oil mist generated during ammonium nitrate/fuel oil (ANFO)
loading operations, and environmental tobacco smoke (ETS). The
parties also agreed to study other potential sampling problems,
including any manufacturing defects of the DPM sampling cassette.
Major conclusions drawn from the study are as follows:
--The analytical method specified by the diesel standard gives an
accurate measure of the TC content of a filter sample and the
analytical method is appropriate for making compliance
determinations of DPM exposures of underground metal and nonmetal
miners.
--SKC satisfactorily addressed concerns over defects in the DPM
sampling cassettes and availability of cassettes to both MSHA and
mine operators.
--Compliance with both the interim and final concentration limits
may be both technologically and economically feasible for metal and
nonmetal underground mines in the study. MSHA, however, has limited
in-mine documentation on DPM control technology. As a result, MSHA's
position on feasibility does not reflect consideration of current
complications with respect to implementation of controls, such as
retrofitting and regeneration of filters. MSHA acknowledges that
these issues may influence the extent to which controls are
feasible. The Agency is continuing to consult with the National
Institute of Occupational Safety and Health, industry and labor
representatives on the availability of practical mine worthy filter
technology.
--The submicron impactor was effective in removing the mineral dust,
and therefore its potential interference, from DPM samples.
Remaining interference from carbonate interference is removed by
subtracting the 4th organic peak from the analysis. No reasonable
method of sampling was found to eliminate interferences from oil
mist or that would effectively measure DPM levels in the presence of
ETS with TC as the surrogate. Results and findings of the study are
summarized below.
Sampling at 31 Mines
There are a number of methods that can measure DPM
concentrations with reasonable accuracy when it is at high
concentrations and the purpose is exposure assessment. These methods
do not at this time provide the accuracy required to support
compliance determinations at the concentration levels required to be
achieved under the DPM rule. The NIOSH Method 5040 provides an
accurate method of determining the total carbon content of a sample
collected in any underground metal or nonmetal mine when the
submicron impactor is used. MSHA's January 2001 regulation requires
using total carbon (TC) as a surrogate for DPM because a consistent
quantitative relationship has been established between total carbon
concentrations and the concentration of DPM as a whole. TC
concentrations measured during the study ranged from 13 to 2065
[mu]/m\3\, with a mean of 345 [mu]/m\3\. To put these sampling
results into context, the interim concentration limit specified in
the final rule, effective after July 19, 2002, is 400 micrograms of
TC per cubic meter of air ([mu]/m\3\). The final concentration limit
is 160 micrograms of TC per cubic meter of air ([mu]/m\3\),
effective after January 19, 2006.
TC concentrations at the non-trona mines were four to five times
higher than at the trona mines. TC concentrations measured using
area samples were found to be 38 to 62 percent of the levels found
using occupational or personal samples.
Interferences
The submicron impactor removes 94% of the mineral dust from DPM
samples. Remaining carbonate interference, if any, is removed by
subtracting the 4th organic peak
[[Page 48671]]
from the analysis. For typical gold mine samples, the interference
from elemental carbon (graphite) would be less than 1.5 [mu]/m\3\.
The use of the impactor also eliminates the need to acidify samples,
including samples from trona mines. For typical non-acidified trona
mine samples, the interference from bicarbonate would be less than
0.5 [mu]/m\3\. Overload of particulate matter on the impactor
substrate to the filter was not observed.
Interference from drill oil mist was found on personal samples
collected on the drillers and on area samples collected in the stope
where drilling was being performed. Use of a dynamic blank did not
eliminate drill oil mist interference. Tests to confirm whether oil
mist from ANFO loading operations could be interference were not
conclusive. Blasting did not interfere with diesel particulate
measurements. MSHA found no reasonable method of sampling to
eliminate interferences from oil mist when TC is used as the
surrogate.
No reliable marker was identified for confirming the presence of
ETS in an atmosphere containing DPM. Use of the impactor does not
remove the ETS as an interferent. No reasonable method of sampling
was found that would effectively measure DPM levels in the presence
of ETS with TC as the surrogate.
Laboratory Analytical Procedures and Sampling Cassettes
Intra- and inter-laboratory analytical imprecision appear to be
in line with other airborne contaminants monitored by MSHA and other
regulatory agencies. Each of the samples collected in the study was
analyzed twice for TC content. To do this, two standard punches were
taken from each exposed and each unexposed (i.e., control) filter.
One punch was always analyzed using the same instrument in MSHA's
laboratory. The second punch from the same filter was either
analyzed in MSHA's laboratory using one of two different instruments
or sent out to one of three other laboratories, NIOSH, Natlsco or
Clayton.
The supplier has satisfactorily addressed concerns over possible
manufacturing defects in the specialized SKC DPM sampling cassette.
MSHA believes that the performance of this cassette will be adequate
for compliance sampling purposes.
Technological Feasibility
Technological feasibility for mine operators to achieve
compliance with the interim and final DPM concentration limits was
assessed for the 31 mines in the study on a mine-by-mine basis using
a computerized Microsoft[reg] 7 Excel spreadsheet program called the
Estimator, combined with sampling results from the 31 mines. The
Estimator mathematically calculates the effect of any combination of
engineering and ventilation controls on existing DPM concentrations
in a given production area of a mine. The analyses were based on the
highest DPM sample result obtained at each mine and all major DPM
emission sources at each mine plus spare equipment.
MSHA, however, has limited in-mine documentation on DPM control
technology. Moreover, these sampling results were obtained at a time
that few mine operators had implemented controls to reduce DPM
concentrations at the subject mines. As a result, MSHA's position on
feasibility does not reflect consideration of current complications
with respect to implementation of controls, such as retrofitting and
regeneration of filters. MSHA acknowledges that these issues may
influence the extent to which controls are feasible. The Agency is
continuing to consult with the National Institute of Occupational
Safety and Health, industry and labor representatives on the
availability of practical mine worthy filter technology.
The study found that five mines were already in compliance with
the interim concentration limit, and another two mines were already
in compliance with the lower, final concentration limit. The
Estimator predicted that eleven of the 31 mines could achieve
compliance with both limits through installation of DPM filters
alone. Ventilation upgrades were specified for only 5 of the 31
mines in this study, and then only to achieve the final
concentration limit.
The Estimator predicted that compliance with the interim and
final concentration limits would be possible without requiring major
ventilation installations (new main fan, repowering main fan, etc.)
or requiring environmental cabs as a means of controlling DPM at any
of the 31 mines. Industry commenters questioned whether practical
mine-worthy filters were available for all engine sizes and whether
more expensive controls would be necessary.
Economic Feasibility
Yearly costs for complying with both the interim and final
concentration limits were determined for each of the 31 mines in the
study. Cost estimates included the purchase cost of DPM controls
specified for that mine in the technological feasibility assessment,
plus related installation and operating costs. The aggregate yearly
cost for all 31 mines to comply with the interim limit was estimated
to be $2.1 million. Compliance with the final limit was estimated to
cost an additional $1.1 million (in 2002 dollars). The yearly total
to comply with both the interim and final concentration limits was
estimated to be $3.2 million. The estimated costs in this report are
based on the accuracy of the Estimator as reported in Appendix A,
and therefore, do not include consideration of current
implementation complications that could increase compliance costs.
MSHA concludes that a regulation is economically infeasible if
it would threaten an industry's viability or competitive structure.
In rulemaking, economic feasibility, as well as technological
feasibility, is not defined for individual firms, but for an
industry. As a screening device, MSHA has historically questioned
economic feasibility if yearly compliance costs equal or exceed one
percent of an industry's annual revenues.
MSHA developed a rough estimate of annual mine revenues using
each mine's annual employee work hours and the production value per
employee hour for the commodity produced. Summing the individual
revenue figures resulted in an estimate of total revenues for the 31
mines in the study of $1.8 billion in 2000.
On this basis, MSHA estimates that the 31 mines in the study
would incur yearly costs equal to 0.12 percent of their annual
revenues to comply with the interim concentration limit and
additional yearly costs equal to 0.06 percent of their annual
revenues to comply with the final concentration limit. To comply
with both the interim and final concentration limits, the 31 mines
would incur yearly costs equal to 0.18 percent of their annual
revenues. Since estimated yearly compliance costs are less than the
screening benchmark of one percent or more of annual revenues, the
data in this report supports a finding that the interim and final
concentration limits are economically feasible. Industry questions
whether all costs for active filter regeneration were considered and
whether the proper controls (that is, filters) were used in the cost
analysis. In particular, industry questions whether compliance with
the interim concentration limit would require some mine operators to
make major ventilation upgrades in their mines.
V. Compliance Assistance
A. Baseline Sampling Summary
Under the DPM Settlement Agreement, MSHA agreed to provide
compliance assistance to the metal and nonmetal underground mining
industry for a one-year period from July 20, 2002 through July 19,
2003. As part of MSHA's compliance assistance activities, the Agency
conducted baseline sampling of miners' personal exposures at every
underground mine covered by the existing regulation. The results of
this sampling were used by MSHA in this preamble to estimate current
DPM exposure levels in these mines. These sampling results also assist
mine operators in developing compliance strategies based on actual
exposure levels. This compliance assistance sampling began in October
2002.
This section summarizes the analytical results of 885 personal DPM
samples collected from 171 mines between October 30, 2002 and March 26,
2003 as part of a compliance assistance initiative. Eleven of the 885
samples were invalid samples due to abnormal sample deposits, broken
cassettes or filters, contaminated backup pads, or instrument or pump
failure. Table V-1 lists the frequencies of invalid samples within each
commodity.
The mines that were sampled produce clay, sand, gypsum, copper,
gold, platinum, silver, gem stones, dimension marble, granite, lead-
zinc, limestone, lime, potash, molybdenum, salt, trona, and other
miscellaneous metal ores. These commodities were grouped into
[[Page 48672]]
four general categories for calculating summary statistics: metal,
stone, trona, and other nonmetal (N/M) mines. These categories were
selected to be consistent with the categories used for analysis of data
for the 31-Mine Study. Most commodities are well represented in this
analysis (average of 5.1 samples per mine). Some of these mines, such
as the gold mines, have an average of only 2.0 samples per mine. MSHA
is conducting additional compliance assistance sampling at these mines,
however, the results are not available for inclusion in this analysis.
Table V-2 lists the number of samples for each category of commodity.
MSHA used the same sampling strategies for collecting baseline
samples as it intends to use for collecting samples for enforcement
purposes. These sampling procedures are described in the Metal and
Nonmetal Health Inspection Procedures Handbook (PH90-IV-4), Chapter A,
``Compliance Sampling Procedures'' and Draft Chapter T, ``Diesel
Particulate Matter Sampling.'' Chapter A includes detailed guidelines
for selecting and obtaining personal samples for various contaminants.
All personal samples were collected for the miner's full-shift
regardless of the number of hours worked, and in the miner's breathing
zone. For the 874 valid personal samples, 83% were collected for at
least eight hours. Total and elemental carbon levels, as well as DPM
levels, are reported in units of micrograms per cubic meter for an 8-
hour full shift equivalent.
The equation used to calculate a 480-minute (8-hour) full shift
equivalent (FSE) exposure of total carbon is Total Carbon Concentration
=
[GRAPHIC] [TIFF OMITTED] TP14AU03.000
Where:
EC = The corrected elemental carbon concentration measured in the
thermal/optical carbon analyzer
OC = The corrected organic carbon concentration measured in the
thermal/optical carbon analyzer
A = The surface area of the deposit on the filter media used to collect
the sample
Flow Rate = Flow rate of the air pump used to collect the sample
measured in Liters per minute
480 minutes = Standardized eight-hour workshift
All levels of carbon or DPM are reported in 8-hour full shift
equivalent (FSE) total carbon concentrations measured in [mu]g/
m3.
Because personal sampling was conducted and no attempt was made to
avoid interference from cigarette smoke or other organic carbon
sources, total carbon was also calculated using the formula prescribed
in the DPM settlement agreement:
Total Carbon Concentration = EC x 1.3.
MSHA agreed to use the lower of the two values (EC x 1.3 or EC +
OC) for enforcement until a final rule is published reflecting EC as
the surrogate.
MSHA collected DPM samples with SKC submicron dust samplers that
use Dorr-Oliver cyclones and submicron impactors. The samples were
analyzed either at MSHA's Pittsburgh Safety and Health Technology
Center, Dust Division Laboratory or at the Clayton Laboratory using
MSHA Method P-13 (NIOSH Analytical Method 5040, NIOSH Manual of
Analytical Methods (NMAM), Fourth Edition, September 30, 1999) for
determining the total carbon content. Each sample was analyzed for
organic, elemental, and carbonaceous carbon and calculated total
carbon. Raw analytical results from both laboratories as well as
administrative information about the sample are stored electronically
in MSHA's Laboratory Information Management System.
If a raw carbon result was greater than or equal to 30 [mu]g/
cm2 of EC or 40 [mu]g/cm2 of TC from the exposed
filter loading, then the analysis was repeated using a separate punch
of the same filter. The results of these two analyses were then
averaged. The companion dynamic blank was also tested for the same
analytes. Otherwise, an unexposed filter from the same manufacturer's
lot was used to correct for background levels. In the event the initial
total carbon result was greater than 100EC [mu]g/
cm2, a smaller punch of the same exposed filter (in
duplicate and corresponding blank) was taken and used in the analysis.
Blank-corrected averaged results were used in the analysis when the
sample was tested in duplicate.
Generally the lowest reporting limit is 3TC [mu]g/
cm2. However, for this analysis, MSHA used all results below
this limit. Due to variations in the analytical method, three samples
have blank corrected elemental carbon results slightly below
0EC [mu]g/m3. This occurred because the
corresponding blank filters have TC results slightly more than the
exposed filter. Median values are not affected by the distribution of
data and MSHA included them where appropriate.
The electronic records of the 885 samples that were available for
analysis were reviewed for inconsistencies. Internally inconsistent or
extreme values were questioned, researched, and verified. Although no
samples were invalidated as a result of the administrative
verification, eleven samples (1.2%) were removed from the data set for
reasons unrelated to the values obtained. The reasons for invalidating
these samples are listed in Table V-1. Accordingly, MSHA has included
874 samples from miners in the analyses. Table V-2 is a list of the
number of valid samples by commodity.
Table V-1.--Reasons for Excluding Samples
----------------------------------------------------------------------------------------------------------------
Reason for excluding from analysis Metal Stone Trona Other N/M Total
----------------------------------------------------------------------------------------------------------------
Abnormal Sample Deposit........................ 0 1 0 0 1
Cassette/Filter Broken......................... 0 2 0 1 3
Contaminated Backup Pad........................ 1 0 0 0 1
Instrument Failure............................. 1 1 0 0 2
Pump Failed.................................... 1 3 0 0 4
--------------
Total...................................... 3 7 0 1 11
----------------------------------------------------------------------------------------------------------------
[[Page 48673]]
Table V-2.--Number of Mines and Valid Samples, by Commodity
----------------------------------------------------------------------------------------------------------------
Average number
Number of Number of of valid
Commodity mines valid samples samples by
mine
----------------------------------------------------------------------------------------------------------------
Metal........................................................... 36 189 5.3
Stone........................................................... 109 519 4.8
Trona........................................................... 3 15 5.0
Other N/M....................................................... 23 151 6.6
-----------------
Total....................................................... 171 874 5.1
----------------------------------------------------------------------------------------------------------------
Table V-3 lists the number of samples collected by specific
commodities at the time the data set was compiled (March 26, 2003) and
sorted by the average number of samples per mine. Although MSHA made
efforts to sample all underground metal and nonmetal mines covered by
this rulemaking within the specified time frame, several mines have few
or no samples for DPM in this analysis. Some metal and nonmetal mining
operations are seasonal in that they are operated intermittently or
operate at less than full production during certain times. These types
of variable production schedules limited efforts to collect compliance
assistance samples. MSHA continued to collect baseline samples during
the compliance assistance period, especially at those mines with a low
sampling frequency or where no samples were collected as of March 26,
2003. Future analyses will incorporate all subsequent valid samples.
Table V-3.--Number of Valid Samples per Mine for Specific Mines
------------------------------------------------------------------------
Average
Specific commodity Number of Number of samples per
mines samples mine
------------------------------------------------------------------------
GEMSTONES MINING, N.E.C.......... 1 2 2.0
GOLD ORE MINING, N.E.C........... 17 34 2.0
DIMENSION MARBLE MINING.......... 3 9 3.0
LIMESTONE........................ 2 6 3.0
TALC MINING...................... 1 3 3.0
CRUSHED & BROKEN MARBLE MINING... 4 16 4.0
GYPSUM MINING.................... 2 8 4.0
CRUSHED & BROKEN STONE MINING, 5 23 4.6
N.E.C...........................
CRUSHED & BROKEN LIMESTONE 85 413 4.9
MINING, N.E.C...................
CLAY, CERAMIC & REFRACTORY 1 5 5.0
MINERALS MINING, N.E.C..........
CONSTRUCTION SAND & GRAVEL 1 5 5.0
MINING, N.E.C...................
COPPER ORE MINING, N.E.C......... 1 5 5.0
CRUSHED & BROKEN SANDSTONE MINING 1 5 5.0
HYDRAULIC CEMENT................. 1 5 5.0
LIME, N.E.C...................... 4 20 5.0
TRONA MINING..................... 3 15 5.0
DIMENSION LIMESTONE MINING....... 4 22 5.5
LEAD-ZINC ORE MINING, N.E.C...... 10 70 7.0
SALT MINING...................... 14 98 7.0
MISCELLANEOUS METAL ORE MINING, 1 9 9.0
N.E.C...........................
MOLYBDENUM ORE MINING............ 2 19 9.5
PLATINUM GROUP ORE MINING........ 2 20 10.0
POTASH MINING.................... 3 30 10.0
SILVER ORE MINING, N.E.C......... 3 32 10.7
AVERAGE OF ALL SAMPLES........... 171 874 5.1
------------------------------------------------------------------------
There are 63 different occupations in underground metal and
nonmetal mines represented in this analysis. The most frequently
sampled occupations are Blaster, Drill Operator, Front-end Loader
Operator, Truck Driver, Scaling (Mechanical), and Mechanic. Table V-4
lists the number of valid samples by occupation and commodity. Only
occupations with 14 or more samples are listed. Occupations with fewer
samples were aggregated for this table.
Table V-4.--Valid Samples, by Occupation and Mine Category
----------------------------------------------------------------------------------------------------------------
Occupation Metal Stone Trona Other N/M Total
----------------------------------------------------------------------------------------------------------------
Truck Driver................................... 55 121 0 7 183
Front-end Loader Operator...................... 23 115 4 13 155
Blaster, Powder Gang........................... 9 72 0 19 100
Scaling (mechanical)........................... 1 53 0 9 63
Drill Operator, Rotary......................... 0 53 0 5 58
Mechanic....................................... 6 10 0 10 26
[[Page 48674]]
Drill Operator, Jumbo Perc..................... 4 9 0 8 21
Mucking Mach. Operator......................... 15 0 0 3 18
Utility Man.................................... 5 3 8 2 18
Scaling (hand)................................. 3 12 0 2 17
Complete Load-Haul-Dump........................ 1 0 0 16 17
Roof Bolter, Rock.............................. 3 6 0 5 14
Drill Operator, Rotary Air..................... 1 12 0 1 14
Crusher Oper/Worker............................ 0 12 0 2 14
All Others Combined............................ 63 41 3 49 156
--------------
Totals................................. 189 519 15 151 874
----------------------------------------------------------------------------------------------------------------
TC levels calculated by EC x 1.3 were lower than TC levels
calculated by OC + EC in 663 (76%) of the 874 baseline samples. Of the
211 samples where TC = OC + EC was the lower value, 64% of the TC = EC
x 1.3 values were within 12% of the TC = OC + EC value. Table V-5
summarizes the results of the baseline samples when determining the TC
level using either EC x 1.3 or OC + EC. Approximately 6.3% of results
did not concur when measuring TC by the two calculations. Approximately
15.7% of the samples were above the 400TC [mu]g/
m3 interim concentration limit when using TC = EC x 1.3 and
approximately 19.5% were above the concentration limit when using TC =
OC + EC. There is 93.7% concurrence between the two methods of
calculating TC and comparing the calculations to the 400TC
[mu]g/m3 interim concentration limit.
Table V-5.--Comparison of Results With 400TC [mu]g/m3 Calculating TC by OC + EC or EC x 1.3
----------------------------------------------------------------------------------------------------------------
EC x 1.3 400 [mu]g/m3
All Valid Samples--OC + EC 400 [mu]g/m3 -------------------------------------- Total
No Yes
----------------------------------------------------------------------------------------------------------------
No................................................... 693 (79.3%) 11 (1.3%) 704 (80.5%)
Yes.................................................. 44 (5.0%) 126 (14.4%) 170 (19.5%)
--------------------
Total.............................................. 737 (84.3%) 137 (15.7%) 874 (100.0%)
----------------------------------------------------------------------------------------------------------------
Table V-6 lists the 19 occupations found to have at least one
sample in which the level of TC was over the interim 400TC
[mu]g/m3 concentration limit (TC = EC x 1.3). Table V-6 is
sorted by the median TC result. The table also lists the minimum value,
median value, and the total number of valid samples for these
occupations. TC values varied widely among all miners' occupations.
Table V-6.--Occupations With at Least One Sample Greater Than or Equal to 400TC [mu]g/m3
----------------------------------------------------------------------------------------------------------------
Occupation Total samples Minimum Median Maximum
----------------------------------------------------------------------------------------------------------------
Engineer........................................ 1 438 438 438
Roof Bolter, Mounted............................ 8 98 335 588
Miner, Stope.................................... 11 165 330 622
Clean Up Man.................................... 2 66 283 499
Mucking Machine Operator........................ 18 15 278 872
Shuttle Car, Diesel............................. 2 95 257 419
Drill Operator, Rotary Air...................... 14 56 231 1145
Belt Crew....................................... 8 26 225 502
Blaster, Powder Gang............................ 101 6 216 960
Drill Operator, Jumbo........................... 21 41 194 708
Complete Load-Haul-Dump......................... 17 42 188 824
Miner, Drift.................................... 14 16 185 1459
Scaling (Hand).................................. 17 18 166 2014
Roof Bolter, Rock............................... 14 63 157 829
Truck Driver.................................... 184 0 155 1074
Front End Loader................................ 155 0 136 1743
Drill Operator, Rotary.......................... 58 3 133 1109
Scaling (Mechanical)............................ 63 0 131 750
Utility Man..................................... 18 29 93 638
Supervisor...................................... 10 1 87 856
Crusher Operator................................ 14 1 47 427
----------------------------------------------------------------------------------------------------------------
Table V-7 and Chart V-1 provide the frequencies and percent of
overexposures among the four commodities. Chart V-2 provides the
frequency of overexposures among the commodities. The metal mines have
the
[[Page 48675]]
highest percent of overexposures followed by stone than other N/M
mines. All 15 samples collected in trona mines were less than
200TC [mu]g/m3. For all samples combined, 15.7%
were above 400TC [mu]g/m3.
Table V-7.--Baseline Samples by Commodity (TC=EC x 1.3)
----------------------------------------------------------------------------------------------------------------
Number 400 Total thn-eq>400
[mu]g/m3 TC [mu]g/m3 TC [mu]g/m3 TC
----------------------------------------------------------------------------------------------------------------
Metal........................................... 148 41 189 21.7
Stone........................................... 435 84 519 16.2
Other N/M....................................... 139 12 151 7.9
Trona........................................... 15 0 15 0.0
-----------------
All Mines................................... 737 137 874 15.7
----------------------------------------------------------------------------------------------------------------
BILLING CODE 4510-43-P
[GRAPHIC] [TIFF OMITTED] TP14AU03.001
[[Page 48676]]
Chart V-3 shows the number of mines with a specific number of
overexposures. Examination of the frequency of mines with one or more
overexposures shows that 51 (29.8%) mines are in this category.
[GRAPHIC] [TIFF OMITTED] TP14AU03.002
At 14 of the mines, all the samples were above 400TC
[mu]g/m3. Between one and five samples were taken at each of
these mines. No overexposures were found in 120 (70%) of the mines
sampled. (See Chart V-4.)
[GRAPHIC] [TIFF OMITTED] TP14AU03.003
BILLING CODE 4510-43-C
Tables V-8 and V-9 summarize sample statistics by commodity for
total carbon calculated by TC = EC x 1.3 and TC = EC + OC respectively.
Overall, the mean TC as calculated by EC x 1.3 is 222 [mu]g/
m3. The median level is 153 [mu]g/m3. The mean TC
level by OC + EC is 263 [mu]g/m3 and the median level is 209
[mu]g/m3. Individual exposure levels of TC vary widely
within all commodities and most mines. The statistics reported in
Tables V-8 and V-9 were chosen to be consistent with those reported in
the 31-Mine Study and the Exposure Assessment.
The mean TC values (EC x 1.3) are somewhat lower than the interim
compliance limit of 400 [mu]g/m3. The mean (median) TC value
for metal mines is 296(239) [mu]g/m3. The mean for stone is
214(136), other N/M is 170(129) and for trona mines is 90(91) [mu]g/
m3. Table V-8 lists additional statistics for EC values
compiled by commodity.
[[Page 48677]]
Table V-8.--Average Levels of Total Carbon by Commodity Measured in [mu]g/m3 (EC x 1.3)
[Estimated 8-hour Full Shift Equivalent TC Concentration ([mu]g/m3)]
----------------------------------------------------------------------------------------------------------------
EC x 1.3 Metal Stone Other N/M Trona All mines
----------------------------------------------------------------------------------------------------------------
Number of Samples.............................. 189 519 151 15 874
Maximum........................................ 2,014 1,743 824 194 2,014
Median......................................... 239 136 129 91 153
Mean........................................... 296 214 170 90 222
------------------------------------------------
Std. Error................................. 19 10 11 13 8
95% CI Upper............................... 333 233 191 119 236
95% CI Lower............................... 258 195 148 62 207
----------------------------------------------------------------------------------------------------------------
The mean TC values as calculated by OC + EC are also somewhat lower
than the interim compliance limit of 400 [mu]g/m3. The mean
(median) TC value for metal mines is 323(285) [mu]g/m3. The
mean for stone is 263(200), other N/M is 202(168) and for trona mines
is 128(126) [mu]g/m3. Table V-9 lists additional statistics
for TC values compiled by commodity.
Table V-9.--Average Levels of Total Carbon by Commodity Measured in [mu]g/m3 (OC + EC)
[Estimated 8-hour Full Shift Equivalent TC Concentration ([mu]g/m3)]
----------------------------------------------------------------------------------------------------------------
OC + EC Metal Stone Other N/M Trona All mines
----------------------------------------------------------------------------------------------------------------
Number of Samples.............................. 189 519 151 15 874
Maximum........................................ 1,742 1,559 740 218 1,742
Median......................................... 285 200 168 126 209
Mean........................................... 323 263 202 128 263
------------------------------------------------
Std. Error................................. 17 11 11 12 8
95% CI Upper............................... 356 284 223 154 278
95% CI Lower............................... 289 243 181 102 248
----------------------------------------------------------------------------------------------------------------
Tables V-10 and V-11 show total DPM exposures for the baseline and
the 31-Mine Study. For baseline sampling DPM was calculated by EC x 1.3
x 1.25. The 1.25 factor represents the assumption that TC comprises 80
percent of DPM. Section VI-B-3 discusses the relationship between
elemental and total carbon. The mean (median) value is 369(299) [mu]g/
m3 for metal mines, 267(170) for stone mines, 212(162) for
other NM, and 113(113) [mu]g/m3 for trona mines. The total
DPM exposures for table V-11 were calculated as (OC + EC) x 1.25. The
mean values from the baseline samples appear to be lower than the mean
values obtained during the 31-Mine Study.
Table V-10.--Baseline DPM Concentrations (EC x 1.3 x 1.25, [mu]g/m \3\), by Mine Category
----------------------------------------------------------------------------------------------------------------
Metal Stone Other N/M Trona All mines
----------------------------------------------------------------------------------------------------------------
Number of Samples.............................. 189 519 151 15 874
Maximum........................................ 2518 2178 1030 242 2518
Median......................................... 299 170 162 113 191
Mean........................................... 369 267 212 113 277
Std. Error................................. 24 12 14 17 9
95% UCL.................................... 416 291 239 149 296
95% LCL.................................... 323 243 185 77 259
----------------------------------------------------------------------------------------------------------------
Table V-11.--Baseline DPM Concentrations ((EC + OC) x 1.25, [mu]g/m \3\), by Mine Category
----------------------------------------------------------------------------------------------------------------
Metal Stone Other N/M Trona All mines
----------------------------------------------------------------------------------------------------------------
Number of Samples.............................. 189 519 151 15 874
Maximum........................................ 2177 1949 925 273 2177
Median......................................... 357 250 211 158 261
Mean........................................... 403 329 252 160 329
Std. Error................................. 21 13 13 15 10
95% CI Upper............................... 445 355 279 193 348
95% CI Lower............................... 361 303 226 127 310
----------------------------------------------------------------------------------------------------------------
[[Page 48678]]
Table V-12.--31-Mine Study DPM Concentrations ( [mu]g/m \3\), by Mine Category
----------------------------------------------------------------------------------------------------------------
Metal Stone Other N/M Trona
----------------------------------------------------------------------------------------------------------------
Number of Samples........................................... 116 105 83 54
Maximum..................................................... 2581 1845 1210 331
Median...................................................... 491 331 341 82
Mean........................................................ 610 466 359 94
Std. Error.............................................. 45 36 27 9
95% CI Upper............................................ 699 537 412 113
95% CI Lower............................................ 522 394 306 75
----------------------------------------------------------------------------------------------------------------
Chart V-5 compares the means from Tables V-10, V-11 and V-12. The
mines selected in the 31-Mine Study (Table V-12) were not randomly
selected and is therefore not considered representative of the
underground M/NM mining industry. Additionally the industry has
continued to change the diesel-powered fleet to low emission engines
that reduce diesel particulate matter exposure. Workers inside
equipment cabs were not sampled during the 31-Mine Study due to
possible interference from cigarette smoke. Personal samples taken
inside cabs were not avoided during baseline compliance assistance
sampling.
[GRAPHIC] [TIFF OMITTED] TP14AU03.004
B. DPM Control Technology
In addition to conducting baseline DPM sampling at underground
metal and nonmetal mines, MSHA participated in a number of compliance
assistance activities directed at improving sampling and assisting mine
operators with selection and implementation of appropriate DPM control
technology. Some of these activities were directed to a segment of, or
the entire mining industry. Others were conducted on a mine specific
basis. In general, those activities directed toward a large number of
mines included outreach programs, workshops, Web site postings and
publications. Those activities directed at an individual mine included
evaluation of a specific control technology, a review of the technology
in use, or that would be available at a specific mine.
Regional DPM Seminars. During September and October 2002, MSHA
conducted regional DPM seminars at Ebensburg, PA, Knoxville, TN,
Lexington, KY, Des Moines, IA, Kansas City, MO, Albuquerque, NM, Coeur
d'Alene, ID, Green River, WY, and Elko, NV. These full-day seminars
were offered free of charge in the major underground metal and nonmetal
mining regions of the country to facilitate attendance by key mining
industry personnel. The seminars covered the health effects of DPM
exposure, the history and specific provisions of the regulation, DPM
controls, DPM sampling, and the DPM Estimator, which is an interactive
computer spreadsheet program used for analyzing a mine's DPM sources
and controls.
NIOSH Diesel Emission Workshops. MSHA staff participated in two
NIOSH Diesel Emissions and Control Technologies in Underground Metal
and Nonmetal Mines in February and March 2003 in Cincinnati, OH and
Salt Lake City, UT. These workshops provided technical presentations
and a forum for discussing issues relating to control technologies for
reducing miners' exposure to particulate matter and gaseous emissions
from the exhaust of diesel-powered vehicles in underground mines, and
to help mine managers, maintenance personnel, safety and health
professionals, and ventilation engineers select and apply diesel
particulate filters and other control technologies in their mines.
Speakers represented MSHA, NIOSH, and several mining companies, and
ample time was provided for questions and in-depth technical discussion
of issues raised by attendees.
[[Page 48679]]
NSSGA DPM Sampling Workshop: As part of the Kentucky Stone
Association Seminar, MSHA staff conducted a diesel particulate sampling
workshop in Louisville, Kentucky from December 11 through 13, 2002. The
three day seminar was hosted by the National Stone Sand and Gravel
Association. On the first day of the seminar, diesel particulate
sampling procedures were reviewed. The participants were trained in
pump calibration, sample train assembly and note taking. On the second,
participants traveled to the Rogers Group Jefferson County Mine and
conducted full shift sampling on underground workers. MSHA technical
support staff took ventilation measurements and collected area samples
to assess mine DPM emissions. On the final day of the seminar, engine
emission and ventilation measurements were reviewed with the
participants. Additionally, the MSHA DPM outreach material was reviewed
and discussed. Approximately 10 industry participants attended the
seminar.
Nevada Mining Association Safety Committee. MSHA staff attended a
meeting of the Nevada Mining Association Safety Committee in Elko, NV
in April 2003 to discuss DPM control technologies. Discussion topics
included bio-diesel fuel blends, various fuel additives and fuel pre-
treatment devices, to mine ventilation, environmental cabs, clean
engines, and diesel particulate filter systems. The mining companies'
experiences with and perspectives on these technologies were discussed,
along with MSHA's experiences, observations made at various mines, and
results of laboratory and field testing.
MSHA South Central Joint Mine Safety and Health Conference. A DPM
workshop was presented at this conference in April 2003 in New Orleans,
LA. This workshop included a detailed history and explanation of the
provisions of the MNM DPM regulation, and a technical presentation on
feasible DPM engineering controls.
2003 Joint National Meeting of the Joseph A. Holmes Safety
Association, National Association of State Mine Inspection and Training
Agencies, Mine Safety Institute of America, and Western TRAM (Training
Resources Applied to Mining). A DPM workshop was presented at this
joint conference in June 2003 in Reno, NV. This workshop included a
detailed history and explanation of the provisions of the MNM DPM
regulation, and a technical presentation on DPM sampling, analytical
tools for identifying and evaluating DPM sources in mines, and feasible
DPM engineering controls.
Web site postings. MSHA created a single source page for DPM final
rules for Metal/Nonmetal Mines on its Web site, www.msha.gov. Links
were established to obtain information on specific topics, including:
--DRAFT Metal and Nonmetal Health Inspection Procedures Handbook,
Chapter T--Diesel Particulate Matter Sampling
--DRAFT Diesel Particulate Matter Sampling Field Notes
--Metal and Nonmetal Diesel Particulate Matter (DPM) Standard Error
Factor for TC Analysis Written Compliance Strategy
--Metal and Nonmetal Diesel Particulate Matter (DPM) Standard Draft
Compliance Guide
--Other Resources
--NIOSH Listserve
--Diesel Emissions and Control Technologies in Underground Metal
and Nonmetal Mines
--Metal and Nonmetal Diesel Particulate Filter Selection Guide
--Baseline DPM Sample Results
--PowerPoint Presentations
--From Compliance Assistance Workshops on Diesel Rule
--Summary of Requirements Mine Safety and Health Administration's
(MSHA's) Standard on Diesel Particulate Matter Exposure of Underground
Metal and Nonmetal Miners that are in effect as of July 20, 2002.
--SKC Diesel Particulate Matter Cassette with Precision-jeweled
Impactor
--Diesel Particulate Matter (DPM) Control Technologies with Percent
Removal Efficiency
--Diesel Particulate Matter (DPM) Control Technologies
--Table I: Non-Catalyzed Particulate Filters, Base Metal
Particulate Filters, and Paper Filters
--Table II: Catalyzed (Platinum Based) Diesel Particulate Filters
--Work Place Emissions Control Estimator
--Advanced Notice of Proposed Rule Making (ANPRM)
--Diesel Particulate Matter Exposure of Underground Metal and
Nonmetal Miners (ANPRM)--09/25/2002
--Final Rules
--Part II--30 CFR Part 57--Diesel Particulate Matter Exposure of
Underground Metal and Nonmetal Miners--01/19/2001
--Part II--30 CFR Part 57--Diesel Particulate Matter Exposure of
Underground Metal and Nonmetal Miners--Delay of Effective Dates--05/21/
2001
--Part II--30 CFR Part 57--Diesel Particulate Matter Exposure of
Underground Metal and Nonmetal Miners--Final Rule and Proposed Rule--
07/05/2001
--Part II--30 CFR Part 57--Diesel Particulate Matter Exposure of
Underground Metal and Nonmetal Miners; Final Rule--02/27/2002
--Part II--30 CFR Part 57--Diesel Particulate Matter Exposure of
Underground Metal and Nonmetal Miners; Final Rule--07/18/2002
--Regulatory Economic Analysis
--Final Regulatory Economic Analysis And Regulatory Flexibility
Analysis for Final Rule on 30 CFR Parts 57 Final Standards and
Regulations--Diesel Particulate Matter Exposure of Underground Metal
and Nonmetal Miners
--News Releases
--MSHA Rules Will Control Miners' Exposure to Diesel Particulate--
01/18/2001
--Program Information Bulletins
--PIB01-10 Diesel Particulate Matter Exposure of Underground Metal
and Nonmetal Miners--08/28/2001
--PIB02-04 Potential Health Hazard Caused by Platinum-Based
Catalyzed Diesel Particulate Matter Exhaust Filters--05/31/2002--
--PIB02-08 Diesel Particulate Matter Exposure of Underground Metal
and Nonmetal Miners-Summary of Settlement Agreement--08/12/2002
In addition to the Web site postings specifically intended for the
metal and nonmetal mining industry, MSHA has created a Diesel Single
Source Page for the coal industry. A list of approved engines is
accessible from the coal page. Many of the other topics found on that
page may also be of interest to the metal and nonmetal mining industry,
particularly for those operations at gassy metal/nonmetal mines where
permissible equipment is required.
Publications: As part of the settlement agreement, MSHA agreed to
issue citations for violations of the interim concentration limit only
after MSHA and NIOSH are satisfied with the performance characteristics
of the SKC sampler. During the 31-Mine study, MSHA observed that the
deposit area of the SKC submicron impactor filter was not as consistent
as those obtained for preliminary evaluation. This was attributed to
inconsistent crimping of the aluminum foil cone on the filter capsule.
NIOSH, in collaboration with MSHA and SKC undertook a project to
redesign the filter capsule and improve the consistency of the deposit
area. This was accomplished by replacing the cone with a 32-mm inside
diameter ring and replacing the 37-mm filter with a 38-mm filter. These
modifications provided a
[[Page 48680]]
consistent 8.04 square centimeter deposit and eliminated leakage around
the filter. The results of this project were prepared into a scientific
publication ``Sampling Results of the Improved SKC Diesel Particulate
Matter Cassette'' by James D. Noll, Robert J. Timko, Linda McWilliams,
Peter Hall, and Robert A. Haney. This paper is being peer reviewed for
publication in a scientific journal. The following abstract was
prepared for the study results:
Diesel particulate matter (DPM) cassettes, manufactured by SKC,
Inc., Eighty Four, PA, are designed to collect airborne particulates
being emitted by diesel powered machinery. These devices, primarily
used in underground metal/non-metal mines, enable officials to
determine miner exposure to DPM. The SKC DPM cassette is a size
selective sampler that was designed by researchers with the U.S.
Bureau of Mines, now a part of the National Institute for
Occupational Safety and Health (NIOSH), and SKC engineers to collect
DPM. This cassette is preferred to a conventional respirable dust
sampler because, if DPM is sampled in the presence of carbonaceous
ore dust, the ore dust and DPM will collect on the quartz filter,
causing the carbon attributed to DPM to be artificially high. In
this study, NIOSH researchers investigated the ability of the SKC
DPM cassette to collect DPM while preventing mineral dust from
collecting on the filter. This cassette discriminated dusts and
efficiently collected DPM in both laboratory and field evaluations.
In the presence of carbon-based mineral dust having an average
concentration of 8 mg/m\3\, no mineral dust was found on SKC DPM
cassette filters. NIOSH researchers did discover that DPM deposits
on filters that were manufactured prior to August 2002 were non-
uniform and inconsistent across the filter surfaces. DPM deposit
cross-sectional areas varied from 6 to 9 cm\2\. To correct this
problem, SKC modified the cassette. The resulting cassette produced
areas of DPM deposit between 8.11 and 8.21 cm\2\, a difference of
less than 2%.
Specific control technology studies. Following the settlement
agreement, MSHA was invited by various mining companies to evaluate the
effectiveness of several different control technologies for diesel
particulate matter. These control technologies included ceramic
filters, bio-diesel fuel and a fuel oxygenator. Company participation
was essential to the success of each study. Ceramic filters were
evaluated in two mines, one where MSHA was the only investigator and
one where NIOSH was the primary investigator. In the MSHA study, DPM on
a production unit was evaluated with and without ceramic filters
installed on the loader and trucks. In the NIOSH study a variety of
ceramic filters were tested in an isolated zone.
Bio-diesel fuel was evaluated in two mines. In one mine, a 20 and
50 percent recycled bio-diesel fuel and a 50 percent new bio-diesel
were evaluated. In the second mine, a 35 percent recycled bio-diesel
fuel and a 35 percent new bio-diesel fuel were evaluated.
The fuel oxygenator system was evaluated in one mine. The mine
exhaust was sampled with and without the units installed. For the tests
with the oxygenator units, the oxygenator units were installed on all
production equipment.
Following is a summary of the five individual mine technology
evaluation studies:
Kennecott Greens Creek Mining Company: The Mine Safety and Health
Administration and Kennecott Greens Creek Mining Company participated
in a collaborative study to verify the efficiency of catalyzed ceramic
diesel particulate filters for reducing diesel emissions. The goal of
the study was the identification of site-specific, practical mine-
worthy filter technology.
This series of tests was designed to determine the reduction in
emissions and personal exposure that can be achieved when ceramic
filters are installed on a loader and associated haulage trucks
operating in a production stope. Relative engine gaseous and diesel
particulate matter emissions were also determined for the equipment
under specific load condition.
The tests were conducted over a two-week period. Three shifts were
sampled with ceramic after-filters installed; and three shifts were
sampled without the after-filters installed. Personal samples were
collected to assess worker exposures. Area samples were collected to
assess engine emissions. Both gaseous and diesel particulate
measurements were taken.
Sampling results indicate significant reductions in both personal
exposures and engine emissions. These results also indicated that
factors such as diesel particulate contamination of intake air, stope
ventilation parameters, and isolated atmospheres in vehicle cabs as
well as the ceramic diesel particulate filters may have a significant
impact on personal exposures. The following findings and conclusions
were obtained from the study:
1. The results of the raw exhaust gas measurements conducted during
the study indicated that the engines were operating properly.
2. The ceramic filters installed on the machines used in this study
did not adversely affect the machine operation. Even with some apparent
visual cracking from the rotation of the filter media, the ceramic
filters removed more than 90% of the DPM. The filters passively
regenerated during machine operation.
3. The Bosch smoke test provides an indication of filter
deterioration; however, the colorization method does not quantify the
results.
4. Personal DPM exposures were reduced by 60 to 68 percent when
after-filters were used.
5. CO levels decreased by up to one-half when the catalyzed filters
were being used. There appeared to be an increase in NO2
when catalyzed filters are being used; however, it was unclear whether
this increase was due to data variability, changes in ventilation rate,
or the use of the catalyzed filters.
6. The use of cabs reduced DPM concentrations by 75 percent when
after-filters were used and by 80 percent when after-filters were not
in use.
7. Ventilation airflow was provided to the stopes through fans with
rigid and bag tubing. Airflow was the same or greater than the
Particulate Index, but typically lower than the gaseous ventilation
rate.
8. The use of ceramic after-filters reduced average engine DPM
emissions by 96 percent.
9. The reduction in personal exposure was not attributed solely to
after-filter performance because other factors such as ventilation,
upwind equipment use, and cabs also influence personal exposure.
Carmeuse North America, Inc., Maysville Mine: MSHA entered into a
collaborative effort with NIOSH, Industry, and the Kentucky Department
of Energy to test DPM emissions and exposures when using various blends
of bio-diesel fuels in an underground stone mine. As part of its
compliance assistance program, MSHA provides support to mining
operations to evaluate diesel particulate control technologies. The
study was initiated by the industry partner, with MSHA and NIOSH
providing support for study design, data collection, and sample and
data analysis. Project funding was provided by Carmeuse and Kentucky
Department of Energy, through the Kentucky Clean Fuels Coalition.
The initial study was conducted in two phases, a 20% bio-diesel and
a 50% bio-diesel blend of recycled vegetable oil, each mixed with 100%
low sulfur No. 2 standard diesel fuel. Baseline conditions were
established using low sulfur No. 2 standard diesel fuel. In a third
phase of the study, a 50% blend of new soy bio-diesel fuel was tested.
Area samples were collected at shafts to assess equipment
emissions. Personal samples were collected to assess worker exposure.
These samples were analyzed by NIOSH using the NIOSH 5040
[[Page 48681]]
method to determine total carbon and elemental carbon concentrations.
Results indicate that significant reductions in emissions and worker
exposure were obtained for all bio-diesel mixtures. These reductions
were in terms of both elemental and total carbon. Preliminary results
for the 20% and 50% recycled vegetable oil indicated 30 and 50 percent
reductions in DPM emissions and exposures, respectively. Preliminary
results for the tests on the 50% blend of new soy bio-diesel fuel,
showed about a 30 percent reduction in DPM emissions and exposures.
Carmeuse North America, Inc., Black River Mine: Following the
success of the bio-diesel tests at Maysville Mine, Carmeuse requested
assistance in continuing the bio-diesel optimization testing at their
Black River Mine. In this test two bio-diesel blends along with a
baseline test were made. For each test personal exposures and the mine
exhaust were tested for two shifts. The two bio-diesel blends included
a 35% recycled vegetable oil and a 35% blend of new soy oil.
Preliminary results for both the 35% recycled vegetable oil and the 35%
blend of new soy bio-diesel fuel showed about a 30 percent reduction in
DPM emissions and exposures.
Rogers Group, Jefferson County Mine: MSHA personnel were invited by
the Company to evaluate a fuel oxygenation system. The oxygenator is
installed in the fuel line of the diesel equipment. The company was
installing the units to increase fuel economy and was interested in
determining their effect on DPM. MSHA conducted baseline sampling prior
to the installation of the units. Personal samples were collected on
production workers and area samples were collected in the mine exhaust
airflow. The units were installed on loaders and trucks. The sampling
was repeated after the units had accumulated 100 hours of operation.
Preliminary results indicated that the use of the fuel oxygenator had
no measurable effect on either DPM exposure or emissions.
Review of the Technology in Use Assistance
Martin Marietta Aggregates, North Indianapolis Mine: MSHA personnel
provided DPM compliance assistance at this mine during a full-day visit
in March 2003. The mine's DPM sampling history was reviewed, along with
current operating and equipment maintenance practices, mine
ventilation, diesel equipment inventory, and steps taken to date and
future plans to reduce DPM exposures. Currently, mechanical ventilation
is used at the mine and an upgrade to the ventilation system was in
progress. The full range of DPM engineering controls was discussed, an
exhaust temperature measurement and data logging system was
demonstrated, and easy-to-use computer software for using such data to
select appropriate DPM filter systems was presented. A simple approach
for measuring the effectiveness of cab air filtering and pressurization
systems was demonstrated, MSHA's computer spreadsheet software for
evaluating the individual and combined effect of DPM emission sources
and controls was presented, the highest DPM-emitting equipment was
identified (so that future equipment-specific DPM control efforts could
be appropriately focused), and the likely effect of various ventilation
system upgrades was discussed.
Martin Marietta Aggregates, Parkville Mine: MSHA personnel provided
DPM compliance assistance at this mine during a full-day visit in April
2003. The mine's DPM sampling history was reviewed, along with current
operating and equipment maintenance practices, mine ventilation, diesel
equipment inventory, and steps taken to date and future plans to reduce
DPM exposures. Mechanical ventilation is currently used at the mine and
an upgrade to the ventilation system was in progress. The full range of
DPM engineering controls was discussed, an exhaust temperature
measurement and data logging system was demonstrated, and easy-to-use
computer software for using such data to select appropriate DPM filter
systems was presented. A simple approach for measuring the
effectiveness of cab air filtering and pressurization systems was
demonstrated, computer spreadsheet software for evaluating the
individual and combined effect of DPM emission sources and controls was
presented, the highest DPM-emitting equipment were identified (so that
future equipment-specific DPM control efforts could be appropriately
focused), and the likely effect of various ventilation system upgrades
was discussed.
Martin Marietta Aggregates, Kaskaskia Mine: MSHA personnel provided
DPM compliance assistance at this mine during a full-day visit in May
2003. The mine's DPM sampling history was reviewed, along with current
operating and equipment maintenance practices, mine ventilation, diesel
equipment inventory, and steps taken to date and future plans to reduce
DPM exposures. Currently, natural ventilation is used at the mine. The
full range of DPM engineering controls was discussed, an exhaust
temperature measurement and data logging system was demonstrated, and
easy-to-use computer software for using such data to select appropriate
DPM filter systems was presented. A simple approach for measuring the
effectiveness of cab air filtering and pressurization systems was
demonstrated, computer spreadsheet software for evaluating the
individual and combined effect of DPM emission sources and controls was
presented, the highest DPM-emitting equipment were identified (so that
future equipment-specific DPM control efforts could be appropriately
focused), and the likely effect of various ventilation system upgrades
was discussed.
Martin Marietta Aggregates, Manheim Mine: MSHA personnel provided
DPM compliance assistance at this mine during a full-day visit in May
2003. The mine's DPM sampling history was reviewed, along with current
operating and equipment maintenance practices, mine ventilation, diesel
equipment inventory, and steps taken to date and future plans to reduce
DPM exposures. Currently, natural ventilation is used at the mine. The
full range of DPM engineering controls was discussed, an exhaust
temperature measurement and data logging system was demonstrated, and
easy-to-use computer software for using such data to select appropriate
DPM filter systems was presented. A simple approach for measuring the
effectiveness of cab air filtering and pressurization systems was
demonstrated, computer spreadsheet software for evaluating the
individual and combined effect of DPM emission sources and controls was
presented, the highest DPM-emitting equipment were identified (so that
future equipment-specific DPM control efforts could be appropriately
focused), and the likely effect of various ventilation system upgrades
was discussed.
Rogers Group, Oldham County Mine: MSHA personnel provided DPM
compliance assistance at this mine during a full-day visit in November
2002. Extensive DPM sampling was conducted at this mine. Both personal
exposure samples and area samples were collected. None of the personal
samples exceeded 160 [mu]g/m\3\. Current operating and equipment
maintenance practices were reviewed, along with mine ventilation,
diesel equipment inventory, and steps taken to date and future plans to
reduce DPM exposures. Mechanical ventilation was provided for the mine.
The full range of DPM engineering controls was discussed. DPM samples
were collected inside and outside equipment cabs. Results from this
survey indicate the environmental cabs provided significant reduction
in
[[Page 48682]]
the DPM exposure of the equipment operators.
Rogers Group, Jefferson County Mine: MSHA personnel provided DPM
compliance assistance at this mine during a full-day visit in December
2002. Both personal exposure samples and area samples were collected.
The highest personal sample, collected on the loader, was 468 [mu]g/
m\3\. The loader was operated with the window open. Current operating
and equipment maintenance practices were reviewed, along with mine
ventilation, diesel equipment inventory, and steps taken to date and
future plans to reduce DPM exposures. Mechanical ventilation was
provided for the mine. The full range of DPM engineering controls was
discussed. The Estimator, MSHA's computer spreadsheet software for
evaluating the individual and combined effect of DPM emission sources
and controls, was presented, the highest DPM-emitting equipment were
identified so that future equipment-specific DPM control efforts could
be appropriately focused. Finally, the likely effect of various
ventilation system upgrades was discussed.
Nalley and Gibson, Georgetown Mine: MSHA personnel provided DPM
compliance assistance at this mine during a full-day visit in May 2003.
The mine's DPM sampling history was reviewed, along with current
operating and equipment maintenance practices, mine ventilation, diesel
equipment inventory, and steps taken to date and future plans to reduce
DPM exposures. DPM samples were collected to assess improvements since
the baseline sampling. Currently, mechanical ventilation provides
airflow to the mine. The full range of DPM engineering controls was
discussed, an exhaust temperature measurement and data logging system
was demonstrated. An easy-to-use computer software for using such data
to select appropriate DPM filter systems was presented. A simple
approach for measuring the effectiveness of cab air filtering and
pressurization systems was demonstrated. The Estimator, MSHA's computer
spreadsheet software for evaluating the individual and combined effect
of DPM emission sources and controls, was presented. The highest DPM-
emitting equipment were identified so that future equipment-specific
DPM control efforts could be appropriately focused, and the likely
effect of various ventilation system upgrades was discussed.
Stone Creek Brick Company: MSHA personnel provided DPM compliance
assistance at this mine during a full-day visit in May 2003. DPM
samples were collected on underground workers. The mine's DPM sampling
history was reviewed, along with current operating and equipment
maintenance practices, mine ventilation, diesel equipment inventory,
and steps taken to date and future plans to reduce DPM exposures. The
mine uses mechanical ventilation to provide airflow to the mine. The
full range of DPM engineering controls was discussed. None of the
equipment were equipped with environmental cabs. The Estimator, MSHA's
computer spreadsheet software for evaluating the individual and
combined effect of DPM emission sources and controls, was presented.
The highest DPM-emitting equipment were identified so that future
equipment-specific DPM control efforts could be appropriately focused.
Also, the likely effect of various ventilation system upgrades was
discussed.
Wisconsin Industrial Sand Co., Maiden Rock Mine: MSHA personnel
provided DPM compliance assistance at this mine during a full-day visit
in May 2003. The mine's DPM sampling history was reviewed, along with
current operating and equipment maintenance practices, mine
ventilation, diesel equipment inventory, and steps taken to date and
future plans to reduce DPM exposures. The full range of DPM engineering
controls was discussed. The Estimator, MSHA's computer spreadsheet
software for evaluating the individual and combined effect of DPM
emission sources and controls, was presented. The highest DPM-emitting
equipment were identified so that future equipment-specific DPM control
efforts could be appropriately focused.
Gouverneur Talc Company, Inc., No. 4 Mine: MSHA personnel provided
DPM compliance assistance at this mine during a full-day visit in May
2003. DPM samples were collected on underground workers. The mine's DPM
sampling history was reviewed, along with current operating and
equipment maintenance practices, mine ventilation, diesel equipment
inventory, and steps taken to date and future plans to reduce DPM
exposures. The full range of DPM engineering controls was discussed, an
exhaust temperature measurement and data logging system was
demonstrated, and easy-to-use computer software for using such data to
select appropriate DPM filter systems was presented. A simple approach
for measuring the effectiveness of cab air filtering and pressurization
systems was demonstrated, a computer spreadsheet software for
evaluating the individual and combined effect of DPM emission sources
and controls was presented, the highest DPM-emitting equipment was
identified (so that future equipment-specific DPM control efforts could
be appropriately focused), and the likely effect of various ventilation
system upgrades was discussed.
Laboratory Compliance Assistance conducted by MSHA: In addition to
the compliance assistance field tests, MSHA's diesel testing laboratory
has been working with manufacturers to evaluate various types of DPM
control technologies. Certain of these technologies can be applied in
either underground metal/nonmetal or coal mines.
Evaluating paper/synthetic media as exhaust filters: MSHA has been
evaluating paper/synthetic media as exhaust filters. These filters have
shown high DPM removal efficiencies in excess of 90% in the laboratory
when tested on MSHA's test engine using the test specified in subpart E
of 30 CFR part 7. The laboratory has tested approximately 20 different
paper/synthetic media from 10 different filter manufacturers. Even
though much of this work is directed to underground coal mine
applications for use on permissible equipment, this technology is
available for use on permissible equipment that is used in underground
gassy metal/nonmetal mines. In addition, some underground coal mine
operators have considered adding exhaust heat exchanger systems to
nonpermissible equipment in order to use the paper/synthetic filters in
place of ceramic filters (a heat exchanger is needed to reduce the
exhaust gas temperature to below 302 [deg]F for these types of
filters). This could also be an option for metal/nonmetal equipment
that would need DPM filter technology, particularly in operations in
gassy mines where permissible equipment is required.
Evaluating Ceramic Filter Systems: MSHA has worked with six
different ceramic filter system manufacturers to evaluate the effects
of their catalytic washcoats on NO2 production. As discussed
elsewhere in this preamble, catalytic washcoats on the ceramic filters
may cause increases in NO2 levels. MSHA used its test engine
and followed the test procedures in subpart E of 30 CFR part 7. MSHA
has posted on its Web site on the Diesel Single Source Page a list of
ceramic filters that have significantly increased NO2
levels. MSHA has also listed the ceramic filters that are not known to
have increased NO2 levels. MSHA also checked the DPM removal
efficiencies for these filters during the laboratory tests and the
efficiency results have agreed with the efficiencies posted on the
Diesel Single Source Page of 85% for cordierite and 87% for silicon
carbide. MSHA also worked with NIOSH during these tests
[[Page 48683]]
to collect DPM samples for EC analysis using the NIOSH 5040 method. The
laboratory results showed that the filters removed EC with efficiencies
up to 99%.
Evaluation of Fuel Oxygenator System: MSHA recently completed
laboratory tests on a Rentar in-line fuel catalyst. The Rentar unit was
installed on a Caterpillar 3306ATAAC which was coupled to a generator.
An electrical load bank was used to load the engine under various
operating conditions. The engine was baselined for gaseous and DPM
emissions without the Rentar; then, the Rentar was installed and
operated for 100 hours of break-in. The gaseous and DPM emission
measurements were repeated after the 100 hour break-in. The preliminary
laboratory results showed some measurable reductions in whole DPM.
Samples were also collected for EC analysis using the NIOSH 5040
method. Those results are currently being evaluated by NIOSH.
Evaluation of a Magnet System: MSHA is preparing to perform
laboratory tests for Ecomax, a manufacturer of a magnet system
installed on the fuel line, oil filter, air intake and radiator. A
preliminary MSHA field test of this product was done at a surface
aggregate operation. The magnetic device demonstrated a 30% reduction
in CO levels. Subsequent laboratory testing will include DPM
measurements.
Additional Testing: MSHA is also planning a lab test on a
manufacturer's fluidized bed, several types of fuel additives, and a
fuel preparative. The test plans and the required test hardware are
currently being discussed with the respective manufactures of these
products.
VI. Exposure Assessment and Literature Update
A. Introduction
Section VI.B summarizes new exposure data that have become
available since publication, on January 19, 2001, of the existing rule
limiting DPM levels in underground metal and nonmetal mines. Next, in
Section VI.C, we survey the most recent scientific literature (April
2000-March 2003) pertaining to adverse health effects of DPM and fine
particulates in general.
B. DPM Exposures in Underground Metal and Nonmetal Mines
In the existing risk assessment (66 FR 5752) we evaluated exposures
based on 355 samples collected at 27 underground U.S. M/NM mines prior
to the rule's promulgation. Mean DPM concentrations found in the
production areas and haulageways at those mines ranged from about 285
[mu]g/m\3\ to about 2000 [mu]g/m\3\, with some individual measurements
exceeding 3500 [mu]g/m\3\. The overall mean DPM concentration was 808
[mu]g/m\3\. All of the samples considered in the existing risk
assessment were collected prior to 1999, and some were collected as
long ago as 1989.
Two new bodies of DPM exposure data, collected subsequent to
promulgation of the 2001 rule, have now been compiled for underground
M/NM mines: (1) Data collected in 2001 from 31 mines for purposes of
the 31-Mine Study (Ref. 31-Mine Study) and (2) data collected between
10/30/2002 and 3/26/2003 from 171 mines to establish a baseline for
future samples (Ref. Baseline Samples, 2003). Both of these datasets
have been placed into the public record, and they are summarized in the
next two subsections below. Following these summaries, we discuss the
relationship between EC and TC, including the ratio of EC to TC
(EC:TC). This discussion will be based entirely on samples taken for
the 31-Mine Study, since those samples were controlled for potential TC
interferences from tobacco smoking and oil mist, whereas the baseline
samples were not.
1. Data from Joint Study
As described in greater detail in MSHA's final report on the 31-
Mine Study, MSHA collected 464 DPM samples in 2001 at 31 underground M/
NM mines. Of these 464 samples, 106 were voided, most of them due to
potential interferences resulting in invalid TC content used to
evaluate DPM exposures. Table VI-1 shows how the remaining 358 valid
DPM samples were distributed across four broad mine categories. All
samples at one of the metal mines were voided, leaving 30 mines with
valid samples indicating DPM concentrations.
Table VI-1.--Number of DPM Samples, by Mine Category
----------------------------------------------------------------------------------------------------------------
Number of mines Average Number of
with valid Number of valid valid samples per
samples samples mine
----------------------------------------------------------------------------------------------------------------
Metal.................................................. 11 116 10.5
Stone.................................................. 9 105 11.7
Trona.................................................. 3 54 18.0
Other.................................................. 7 83 11.9
--------------------
Total.............................................. 30 358 12.5
----------------------------------------------------------------------------------------------------------------
Table VI-2 summarizes the valid DPM concentrations observed in each
mine category, assuming that submicrometer TC, as measured by the SKC
sampler, comprises 80 percent of all DPM. The mean concentration across
all 358 valid samples was 432 [mu]g/m\3\ (Std. error = 21.0 [mu]g/
m\3\). The mean concentration was greatest at metal mines, followed by
stone and ``other N/M.'' At the three trona mines sampled, both the
mean and median DPM concentration were substantially lower than what
was observed for the other categories. This was due to the increased
ventilation used at these mines to control methane emissions.
Table VI-2.--DPM Concentrations ([mu]g/m\3\), By Mine Category. DPM Is Estimated by TC/0.8
----------------------------------------------------------------------------------------------------------------
Metal Stone Trona Other N/M
----------------------------------------------------------------------------------------------------------------
Number of samples........... 116 105 54 83
Minimum..................... 46. 16. 20. 27.
Maximum..................... 2581. 1845. 331. 1210.
Median...................... 491. 331. 82. 341.
[[Page 48684]]
Mean........................ 610. 465. 94. 359.
-----------------------------
Std. Error.............. 44.7 36.0 9.4 26.6
95% UCL................. 699. 537. 113. 412.
95% LCL................. 522.0 394. 75. 306.
----------------------------------------------------------------------------------------------------------------
After adjusting for differences in sample types and in occupations
sampled, DPM concentrations at the non-trona mines were estimated to be
about four to five times the concentrations found at the trona mines.
Although there were significant differences between individual mines,
the adjusted differences between the general categories of metal,
stone, and other N/M mines were not statistically significant.\1\ For
the 304 valid samples taken at mines other than trona, the mean DPM
concentration was 492 [mu]g/m\3\ (Std. error = 23.0).
---------------------------------------------------------------------------
\1\ These conclusions derive from an analysis of variance, based
on TC measurements, as described in the report of the 31-Mine Study.
They depend on an assumption that the ratio of DPM to TC is
uncorrelated with mine category, sample type (i.e., personal or
area), and occupation.
---------------------------------------------------------------------------
Again assuming that submicrometer TC as measured by the SKC sampler
comprises 80 percent of DPM, the mean DPM concentration observed was
1019 [mu]g/m\3\ at the single mine exhibiting greatest DPM levels. Four
of the nine valid samples at this mine exceeded 1487 [mu]g/m\3\. In
contrast, DPM concentrations never exceeded 500 [mu]g/m\3\ at 8 of the
30 mines with valid samples (2 of the 11 metal mines, 1 of the 3 stone,
all 3 trona, and 2 of the 7 other N/M). (Note that 500 [mu]g/m\3\ is
the whole particulate equivalent of the 400 [mu]g/m\3\ interim
standard.) Some individual measurements exceeded 200DPM [mu]g/m\3\ at
all but one of the mines sampled.
2. Baseline Data
An analysis of MSHA's baseline sampling appears in Section V,
Compliance Assistance, and is used as the basis for this dicussion.
Table VI-1 summarizes, by general commodity, the EC levels measured
during this sampling. The overall mean eight-hour full shift equivalent
EC concentration of samples in this study was 170 [mu]g/m\3\, and the
overall median was 117 [mu]g/m\3\. Table VI-2 provides a similar
summary for estimated DPM levels, using TC/0.8 and TC [ap] 1.3 x EC.\2\
Under these assumptions, the estimated mean DPM level was 277 [mu]g/
m\3\, and the median was 191 [mu]g/m\3\. Since the baseline data and
the 31-Mine study both showed significantly lower levels at trona mines
than at other underground M/NM mines, Tables VI-7 and VI-8 present
overall results both including and excluding the three underground
trona mines sampled.
---------------------------------------------------------------------------
\2\ The relationship DPM [ap] TC/0.8 is the same as that assumed
in the existing risk assessment. The relationship TC [ap] 1.3 x EC
was formulated under the settlement agreement, based on TC:EC ratios
observed in the joint 31-Mine Study, as described in the next
subsection of this exposure assessment.
Table VI-1.--Baseline EC Concentrations
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-hour full shift equivalent EC concentration--([mu]g/m\3\)
-----------------------------------------------------------------------------------------
Total
Metal Stone Other N/M Trona Total excluding
Trona
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of samples............................................. 189 519 151 15 874 859
Maximum....................................................... 1549 1340 634 149 1549 1549
Median........................................................ 184 104 99 70 117 120
Mean.......................................................... 227 164 130 69 170 172
---------------------------------------------------------------
Std. Error................................................ 14.6 7.5 8.5 10.3 5.8 5.9
95% UCL................................................... 256 179 147 92 182 184
95% LCL................................................... 198 150 115 47 159 161
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table VI-2.--Baseline DPM Concentrations
--------------------------------------------------------------------------------------------------------------------------------------------------------
Estimated 8-hour full shift equivalent DPM concentration--([mu]g/m\3\)
-----------------------------------------------------------------------------------------
Total
Metal Stone Other N/M Trona Total excluding
Trona
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of samples............................................. 189 519 151 15 874 859
Maximum....................................................... 2518. 2178. 1030. 242. 2518. 2518.
Median........................................................ 299. 170. 162. 113. 191. 195.
Mean.......................................................... 369. 267. 212. 113. 277. 280.
---------------------------------------------------------------
Std. Error................................................ 23.8 12.2 13.8 16.7 9.4 9.5
95% UCL................................................... 416. 291. 239. 149. 295. 299.
95% LCL................................................... 323. 243. 185. 77. 259. 261.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline EC sample results varied widely between mines within
commodities and also within most mines. Table VI-3 summarizes baseline
EC results for the 19 occupations found to have at least one sample
where the
[[Page 48685]]
EC level exceeded the proposed 308 [mu]g/m\3\ 8-hour full shift
equivalent interim EC limit. As indicated by the table, EC levels
varied widely within each occupation.
Table VI-3.--Baseline EC Concentrations for Occupations With at Least One Value Exceeding Proposed Interim EC
Limit
----------------------------------------------------------------------------------------------------------------
8-hour full shift equivalent EC concentration ([mu]g/m\3\)
---------------------------------------------------------------------------
Occupation Number of valid
samples Minimum Median Maximum
----------------------------------------------------------------------------------------------------------------
Scaling (hand)...................... 17 14 128 1,549
Front-end Loader.................... 155 0 104 1,340
Miscoded............................ 3 395 450 1,123
Drill Operator...................... 93 2 122 880
Truck Driver........................ 183 0 118 826
Blaster, Power Gang................. 100 5 165 738
Miner, Drift........................ 13 12 134 712
Mucking Machine..................... 18 12 213 671
Supervisor.......................... 10 1 67 658
Roof Bolter......................... 22 48 167 638
Complete Loader..................... 17 32 145 634
Scaling (mechanical)................ 63 0 101 577
Utility Man......................... 18 22 71 491
Miner, Stope........................ 11 127 254 479
Belt Crew........................... 8 20 173 386
Cleanup Man......................... 2 51 217 384
Engineer............................ 1 337 337 337
Crusher operator.................... 14 1 36 328
Shuttle car operator................ 3 14 73 323
----------------------------------------------------------------------------------------------------------------
Figure VI-1 depicts, by mine category, the percentage of baseline
samples that exceed the proposed interim limit of 308 [mu]g/
m3. Underground metal mines exhibited the highest proportion
of samples exceeding this limit, followed by stone and then other
nonmetal mines. All 15 samples collected in the three trona mines met
the proposed limit. Across all commodities, 15.7 percent of the 874
valid baseline samples exceeded the interim EC limit.
[GRAPHIC] [TIFF OMITTED] TP14AU03.005
Figure VI-2 shows how samples exceeding the proposed interim EC
limit were distributed over individual mines. One to five baseline
samples were taken at each mine. In 120 of the 171 mines sampled (70
percent), none of the
[[Page 48686]]
baseline EC measurements exceeded 308 [mu]g/m3. The
remaining 51 mines (30 percent) had at least one sample for which EC
exceeded 308 [mu]g/m3. All samples taken at 14 of the mines
exceeded the proposed interim limit.
[GRAPHIC] [TIFF OMITTED] TP14AU03.006
3. Relationship Between Elemental and Total Carbon
Unlike the 31-Mine Study, no special precautions were taken during
MSHA's baseline sampling to avoid tobacco smoke or other substances
that could potentially interfere with using TC (i.e., EC + OC) as a
surrogate measure of DPM. Therefore, the baseline data should not be
used to evaluate the OC content of DPM or the ratio of EC to TC within
DPM. In the 31-Mine Study, great care was taken to void all samples
that may have been exposed to tobacco smoke or other extraneous sources
of organic carbon. Accordingly, the analysis of the EC:TC ratio we
present here relies entirely on data from the 31-Mine Study. It is
important to note that most of the samples in this study were taken in
the absence of exhaust filters to control DPM emissions. Since exhaust
filters may have different effects on EC and OC emissions, the results
described here apply only to mine areas where exhaust filters are not
employed.
Figure VI-3 plots the EC:TC ratios observed in the 31-Mine Study
against the corresponding TC concentrations. The various symbols shown
in the plot identify samples taken at the same mine. The EC:TC ratio
ranged from 23 percent to 100 percent, with a mean of 75.7 percent and
a median of 78.2 percent. Note that the reciprocal of 0.78, which is
1.3, equals the median of the TC:EC ratio observed in these samples.\3\
The 1.3 TC:EC ratio was the value accepted, under terms of the
settlement agreement, for the purpose of temporarily converting EC
measurements to TC measurements.
---------------------------------------------------------------------------
\3\ The median of reciprocal values is always equal to the
reciprocal of the median. This relationship does not hold for the
mean.
---------------------------------------------------------------------------
[[Page 48687]]
[GRAPHIC] [TIFF OMITTED] TP14AU03.007
The existing rule defines an interim TC limit of 400 [mu]g/m\3\.
Under the current proposal, this interim limit would be replaced with
an interim EC limit of 308 [mu]g/m\3\. Table VI-4 indicates the impact
of this proposed change, based on the EC and TC data obtained from the
31-Mine Study. Both the 400 [mu]g/m\3\ TC limit and the 308 [mu]g/m\3\
EC limit were exceeded by about 31 to 32 percent of the samples. The
difference (one sample out of 358) is not statistically significant in
the aggregate. Seven samples, however, exceeded the TC limit but not
the EC limit, and six samples exceeded the EC limit but not the TC
limit.
[[Page 48688]]
Table VI-4.--Compliance With 400 [mu]g/m\3\ TC Limit and/or Proposed 308 [mu]g/m\3\ EC Limit.
[Numbers in parentheses are percentages.]
----------------------------------------------------------------------------------------------------------------
TC 400 [mu]g/m\3\
EC 308 [mu]g/m\3\ -------------------------------------- Total
No Yes
----------------------------------------------------------------------------------------------------------------
no..................................................... 239 (66.8) 7 (2.0) 246 (68.7)
yes.................................................... 6 (1.7) 106 (29.6) 112 (31.3)
--------------------
Total.............................................. 245 (68.4) 113 (31.6) 358 (100.0)
----------------------------------------------------------------------------------------------------------------
C. Health Effects Literature Update
We have identified additional scientific literature pertaining to
health effects of fine particulates in general and DPM in particular
published subsequent to the January 19, 2001 final rule.
Table VI-5 Studies of Human Respiratory and Immunological Effects, 2000-2002
----------------------------------------------------------------------------------------------------------------
Authors, year Description Key results
----------------------------------------------------------------------------------------------------------------
Frew et al., 2001............... 25 healthy subjects and 15 subjects Both the asthmatic and healthy
with mild asthma were exposed to subjects developed increased airway
diesel exhaust (108 [mu]g/m\3\) or resistance after exposure to diesel
filtered air for 2 hr, with emissions, but airway inflammatory
intermittent exercise. Lung function responses were different for the 2
was assessed using a computerized groups. The healthy subjects showed
whole body plethysmograph. Airway statistically significant BW
responses were sampled by bronchial neutrophilia and BAL lymphocytosis 6
wash (BW), bronchoalveolar lavage hr after exposure. The neutrophilic
(BAL), and mucosal biopsies 6 hr. response of the healthy subjects was
after ceasing exposures. less intense than that seen in a
previous study using a DPM
concentration of 300 [mu]g/m\3\.
Fusco et al., 2001.............. Analysis of daily hospital admissions Respiratory admissions among adults
for acute respiratory infections, were significantly correlated with CO
COPD, asthma, and total respiratory and NO2 levels, but not with
conditions in Rome, Italy. suspended particles. The authors
noted that since CO and NO2 are good
indicators of combustion products in
vehicular exhaust, the detected
effects may be due to unmeasured fine
and ultrafine particles.
Holgate et al., 2002............ 25 healthy and 15 asthmatic subjects Healthy and asthmatic subjects
were exposed for 2 hours to 100 [mu]g/ exhibited evidence of
m\3\ of DPM and to filtered air on bronchioconstriction immediately
separate days. Another 30 healthy after exposure.
subjects were exposed for 2 hours to Biochemical tests of inflammation
DPM concentrations ranging from 25 to yielded mixed results but showed
311 [mu]g/m\3\ and compared to 12 small inflammatory changes in healthy
different healthy subjects exposed to subjects after DPM inhalation.
filtered air. Exposure effects were
assessed using lung function tests
and biochemical tests of bronchial
tissue samples.
Oliver et al., 2001............. Pulmonary function tests and After adjusting for smoking and some
questionnaire data were obtained for other potential confounders, HH
359 ``heavy and highway'' (HH) workers showed elevated risk of
construction workers. Intensity of asthma. One subgroup (tunnel workers)
DPM exposure was estimated according also showed elevated risk of both
to job classification. Duration of undiagnosed asthma and chronic
exposure was estimated based on bronchitis, compared to other HH
length of union membership. workers.
Respiratory symptoms appeared to
decline with exposure duration as
measured by length of union
membership. The authors interpreted
this as suggesting that HH workers
tend to leave their trade when they
experience adverse respiratory
symptoms.
Salvi et al., 2000.............. 15 healthy nonsmoking volunteers were Diesel exhaust exposure enhanced gene
exposed to 300 [mu]g/m\3\ DPM and transcription of IL-8 in the
clean air for one hour at least three bronchial tissue and airway cells and
weeks apart. increased IL-8 and GRO-[alpha]
Biochemical analyses were performed on protein expression in the bronchial
bronchial tissue and bronchial wash epithelium. This was accompanied by a
cells obtained six hours after each trend toward increased IL-5 mRNA gene
exposure. transcripts in the bronchial tissue.
Study showed effects on chemokine and
cytokine production in the lower
airways of health adults. These
substances attract and activate
leukocytes. They are associated with
the pathophysiology of asthma and
allergic rhinitis.
[[Page 48689]]
Svartengren et al., 2000........ Twenty nonsmoking subjects with mild Subjects with PM2.5 exposure--100
allergic asthma were exposed for 30 [mu]g/m\3\ exhibited slightly
minutes to high and low levels of increased asthmatic responses.
engine exhaust air pollution on two Associations with adverse outcome
separate occasions at least four variables were weaker for
weeks apart. Respiratory symptoms and particulates than for NO2.
pulmonary function were measured
immediately before, during and after
both exposure periods. Four hours
after each exposure, the test
subjects were challenged with a low
dose of inhaled allergen. Lung
function and asthmatic reactions were
monitored for several hours after
exposure.
----------------------------------------------------------------------------------------------------------------
Table VI-6.--Review Articles on Respiratory and Immunological Effects, 1999-2002
----------------------------------------------------------------------------------------------------------------
Authors, Year Description Key results
----------------------------------------------------------------------------------------------------------------
Gavett and Koren, 2001.......... Summarizes results of EPA studies done Studies indicate that PM enhances
to determine whether PM can enhance allergic sensitization in animal
allergic sensitization or exacerbate models of allergy and exacerbate
existing asthma or asthma-like inflammation and airway hyper-
responses in humans and animal models. responsiveness in asthmatics and
animal models of asthma.
Pandya et al. 2002.............. Reviews human and animal research Evidence indicates that DPM is
relevant to question of whether DPM associated with the inflammatory and
is associated with asthma. immune responses involved in asthma,
but DPM appears to have a far greater
impact as an adjuvant with allergens
than alone. DPM appears to augment
IgE, trigger eosinophil
degranulation, and stimulate release
of numerous cytokines and chemokines.
DPM may also promote the cytotoxic
effects of free radicals in the
airways.
Patton and Lopez, 2002.......... Review of evidence and mechanisms for Evidence suggests that air pollutants
the role of air pollutants in (including DPM) ``affect allergic
allergic airway diseases. response by different mechanisms.
Pollutants may increase total IgE
levels and potentiate the initial
sensitization to allergens and the
IgE response to a subsequent allergen
exposure. Pollutants also may act by
increasing allergic airway
inflammation and by directly
stimulating airway inflammation. In
addition, it is well known that
pollutants can be direct irritants of
the airways, increasing symptoms in
patients with allergic syndromes.''
Peden, 2002..................... Review of ``studies that exemplify the DPM ``may play a significant role not
impact of ozone, particulates, and only in asthma exacerbation but also
toxic components of particulates on in TH2 inflammation via the actions
asthma.''. of polyaromatic hydrocarbons on B
lymphocytes.'' ``* * * PM in which
the active agents are biologically
active metal ions and organic
residues * * * may have significant
effects on asthma, especially
modulating immune function, as
demonstrated by the role of
polyaromatic hydrocarbons from diesel
exhaust in IgE production.''
Sydbom et al. 2001.............. Review of scientific literature on The epidemiological support for
health effects of diesel exhaust, particle effects on asthma and
especially the DPM components. respiratory health is very evident;
and respiratory, immunological, and
systemic effects of DPM have been
documented in a wide variety of
experimental studies.
Acute effects of DPM exposure include
irritation of the nose and eyes, lung
function changes, and airway
inflammation.
Exposure studies in healthy humans
have documented a number of profound
inflammatory changes in the airways,
notably, before changes in pulmonary
function can be detected. Such
effects may be even more detrimental
in subjects with compromised
pulmonary function.
Ultrafine particles are currently
suspected of being the most
aggressive particulate component of
diesel exhaust.
----------------------------------------------------------------------------------------------------------------
[[Page 48690]]
Table VI-7.--Studies Relating to Cardiovascular and Cardiopulmonary Effects, 2000-2002
----------------------------------------------------------------------------------------------------------------
Authors, Year Description Key Results
----------------------------------------------------------------------------------------------------------------
Lippmann et al., 2000........... Day-to-day fluctuations in particulate After adjustment for the presence of
air pollution in the Detroit area other pollutants, significant
were compared with corresponding associations were found between
fluctuations in daily deaths and particulate levels and an increased
hospital admissions for 1985-1990 and risk of death due to circulatory
1992-1994. causes. However, relative risks were
about the same for PM2.5 and larger
particles.
Magari et al., 2001............. Longitudinal study of a male After adjusting for potential
occupational cohort examined the confounding factors such as age, time
relationship between PM2.5 exposure of day, and urinary nicotine level,
and cardiac autonomic function. PM2.5 exposure was significantly
associated with disturbances in
cardiac autonomic function.
Pope et al., 2002............... Prospective cohort mortality study, After adjustment for other risk
based on data collected for Cancer factors potential using a variety of
Prevention II study, which began in statistical consumption, and methods,
1982. fine particulate (PM2.5) exposures
Questionnaires were used to obtain were significantly associated with
individual risk factor data (age, cardiopulmonary mortality (and also
sex, race, weight, height, smoking with lung cancer).
history, education, marital status, Each 10-[mu]g/m3 increase in mean
diet, alcohol confounders, and level of ambient fine particulate air
occupational exposures). For about pollution was associated with an
500,000 adults, these were combined increase of approximately 6 percent
with air pollution data for in the risk of cardiopulmonary
metropolitan areas throughout the mortality.
United States and with vital status
and cause of death data through 1998.
Samet et al., 2000a, 2000b...... Time series analyses were conducted on Results of both the 20-city and 90-
data from the 20 and 90 largest U.S. city mortality analyses are
cities to investigate relationships consistent with an average increase
between PM10 and other pollutants and in cardiovascular and cardiopulmonary
daily mortality. deaths of more than 0.5% for every 10
[mu]g/m3 increase in PM10 measured
the day before death.
Wichmann et al., 2000........... Time series analyses were conducted on Higher levels of both fine and
data from Erfurt, Germany to ultrafine particle concentrations
investigate relationships between the were significantly associated with
number and mass concentrations of increased mortality rate.
ultrafine and fine particles and
daily mortality.
----------------------------------------------------------------------------------------------------------------
Table VII.-8.--Studies and Review of Article on Cancer Effects, 2000-2002
----------------------------------------------------------------------------------------------------------------
Authors, year Description Key results
----------------------------------------------------------------------------------------------------------------
Boffetta et al, 2001............ Cohort studied was entire Swedish Relative risks (RR) of lung cancer
working population (other than among men were 0.95, 1.1, and 1.3 for
farmers). Job title and industry were job categories with low, medium, and
classified according to probability high exposure to diesel exhaust
and intensity of diesel exhaust compared to workers in jobs
exposure for years 1960 and 1970, and classified as having no occupational
according to authors' confidence in exposure. Elevated risks for medium
assessment. and high exposure groups were
Cohort members followed up for statistically significant, and no
mortality for 19-year period from similar pattern was observed for
1971 through 1989. Cause of death, other cancer types.
specific cancer type, when
applicable, obtained through national
registries.
Gustavsson et al, 2000.......... Case-control study involving all 1,042 Adjusted RR for the highest quartile
male cases of lung cancer and 2,364 of estimated lifetime exposure was
randomly selected controls (matched 1.63, compared to the group with no
by age and inclusion year) in exposure.
Stockholm County, Sweden from 1985
through 1990. Occupational exposure,
smoking habits, and other risk
factors assessed based on written
questionnaires mailed to subjects or
next of kin. Relative Risk (RR)
estimates adjusted for age, selection
year, tobacco smoking, residential
radon, occupational exposures to
asbestos and combustion products, and
environmental exposure to NO2.
Pope et al., 2002............... Prospective cohort lung cancer After adjusting for other risk factors
mortality study using data collected and potential cofounders, chronic
for the American Cancer Society PM2.5 exposures found to be
Cancer Prevention II Study (began significantly associated with
1982). Questionnaires used to obtain elevated lung cancer mortality.
individual risk factor data including Each 10 g/m3 increase in mean level of
age, sex, race, weight, height, ambient fine particulate air
smoking history, education, marital pollution associated with
status, diet, alcohol consumption, statistically significant increase of
and occupational exposures. This risk approximately 8 percent in risk of
factor data combined with air lung cancer mortality.
pollution data for metropolitan areas
throughout United States and vital
status and cause of death data
through 1998 for about 500,000 adults.
[[Page 48691]]
Boffetta and Silverman, 2001.... Meta-analysis performed on 44 Overall Relative Risk (RR) was 1.37
independent results from 29 distinct for heavy equipment operators, 1.17
studies of bladder cancer in for truck drivers, 1.33 for bus
occupational groups having varying drivers, and 1.13 for JEM.
exposure to diesel exhaust (studies Quantitiatives meta-analysis also
included only if at least 5 years performed on 8 independent studies
between first exposure and bladder showing results for ``high'' diesel
cancer development). Separate exposure. Combined results were
quantitative meta-analyses performed RR=1.23 for ``any exposure,'' and
for heavy equipment operators, truck RR=1.44 for ``high exposure.''
drivers, bus drivers, and studies
with semi-quantitative exposure
assessments based on a job exposure
matrix (JEM).
Zeegers et al., 2001............ Prospective case-cohort study Relative risk for category with
involving 98 bladder cancer cases highest cumulative probability of
among men occupationally exposed to exposure was 1.17.
diesel exhaust. A cohort of 58,279
men who were 55-69 years old in 1986
was followed up through 1992.
Exposure assessed by job history
given on self- administered
questionnaire, combined with expert
assessment of exposure probability.
``Cumulative probability of
exposure'' determined by multiplying
job duration by exposure probability.
Four categories of relative cumulative
exposure probability defined: none,
lowest third, middle third, highest
third. Relative risks adjusted for
age, cigarette smoking, and exposure
to other occupational risk factors.
Ojajarvi et al, 2000............ Meta-analysis of 161 independent Based on 20 populations, no elevated
results (populations) from 92 studies risk associated with diesel exposure.
on relationship between worksite Combined relative risk was 1.0. This
exposures and pancreatic cancer. result consistent with existing risk
assessment which identified lung and
bladder cancer as the only forms of
cancer for which there was evidence
of an association with DPM exposure.
Szadkowska-stanczyk and Literature review of studies relating Authors conclude long-term exposure
Ruszkowska, 2000. to carcinogenic effects of diesel (20 years) associated with
emissions. (Article in Polish; MSHA 30% to 40% increase in lung cancer
had access only to English risk in workers in transport
translation of Abstract.). industry.
----------------------------------------------------------------------------------------------------------------
Table VI-8.--Studies On Toxicological Effects of DPM Exposure, 2000-2002
----------------------------------------------------------------------------------------------------------------
Authors, Year Description Key results Agent(s) of toxicity
----------------------------------------------------------------------------------------------------------------
Al-Humadi et al., 2002........... IT instillation in rats Exposure to DPM or DPM and carbon black
of 5 mg/kg saline, DPM, carbon black augments particles.
or carbon black. OVA sensitization;
particle composition
(of DPM) may not be
critical for adjuvant
effect.
Bunger et al., 2000.............. In Vitro: assessment of Production of black DE generated from diesel
content of polynuclear carbon and polynuclear engine
aromatic compounds and aromatic engine DPM collected on filters
mutagenicity of DPM compounds that are and soluble organic
generated from four mutagenic; correlation extracts prepared.
fuels, Ames assay used. with sulfur content of
fuel and engine speed.
Carero et al., 2001.............. In Vitro: assessment of DNA damage produced, but DPM, urban particulate
DPM, carbon black, and no cytotoxicity matter (UPM), and
urban particulate matter produced. carbon black (CB).
genotoxicity, human DPM, UPM purchased from
alveolar epithelial NIST, CB purchased from
cells used. Cabot.
Castranova et al., 2001.......... In Vitro: assessment of DPM depresses No information on
DPM on alveolar antimicrobial potential generation of DPM
macrophage functions and of macrophages, thereby (details may be found in
role of adsorbed increasing previous publications
chemicals; rat alveolar susceptibility of lung from this lab).
macrophages used. to infections, this
In Vivo: assessment of inhibitory effect due
DPM on alveolar to adsorbed chemicals
macrophage functions and rather than carbon core
role of adsorbed of DPM.
chemicals, use of IT
instillation in rats.
[[Page 48692]]
Fujimaki et al., 2001............ In Vitro: assessment of Adverse effects of DE on DE generated from diesel
cytokine production, cytokine and antibody engine DPM, CO2, SO2 NO/
spleen cells used. production by creating NO2/NOX measured.
In Vivo: assessment of an imbalance of helper
cytokine production T-cell functions.
profile following IP
sensitization to OA and
subsequent exposure to
1.0 mg/mg3 DE for 12 hr/
day, 7 days/week over 4
weeks, mouse inhalation
model used.
Gilmour et al., 2001............. In Vivo: assessment of Exposure to woodsmoke Woodsmoke, oil furnace
infectivity and increased emissions, and residual
allergenicity following susceptibility to and oil fly ash (ROFA) used
exposure to woodsmoke, severity of
oil furnace emissions, streptococcal
or residual oil fly ash, infection, exposure to
mouse inhalation model residual oil fly ash
used, IT instillation increased pulmonary
used in rats. hypersensitivity
reactions.
Hsiao et al., 2000............... In Vitro: assessment of Seasonal variations in PM collected Hong Kong
cytotoxic effects (cell PM, in their area and solvent-
proliferation, DNA solubility, and in extractable organic
damage) of PM2.5 (fine their ability to compounds used.
PM) and PM2.5-10 (coarse produce cytotoxicity.
PM), rat embryo Long-term exposure to
fibroblast cells used. non-killing doses of PM
may lead to
accumulation of DNA
lesions.
Kuljukka-Rabb et al., 2001....... In Vitro: assessment of Temporal and dose- Some DPM purchased from
of adduct formation dependent DNA adduct NIST, some DPM
following exposure to formation by PAHs. collected on filters
DPM, DPM extracts, Carcinogenic PAHs from from diesel vehicle,
benzo[a]pyrene, or 5- diesel extracts lead to and solvent-extractable
methyl-chrysene, mammary stable DNA adduct organic compounds used.
carcinoma cells used. formation.
Moyer et al., 2002............... In Vivo: 2-phase Induction and/or Indium phosphide, cobalt
retrospective study, exacerbation of sulfate heptahydrate,
review of NTP data from arteritis following vanadium pentoxide,
90-day and 2-yr chronic exposure gallium arsenide,
exposures to (beyond 90-day) to nickel oxide, nickel
particulates, use of particulates. subsulfide, nickel
mouse inhalation model. sulfate hexahydrate,
talc, molybdenum
trioxide used.
Saito et al., 2002............... In Vivo: assessment of DE alters immunological DE generated from diesel
cytokine expression responses in the lung engine DPM, CO, SO2,
following exposure to DE and may increase and NO2 measured.
(100 [mu]g/m3 or 3 mg/m3 susceptibility to
DPM) for 7-hrs/day x 5 pathogens, low-dose DE
days/wk x 4 wks, mouse may induce allergic/
inhalation model used.. asthmatic reactions.
Sato et al., 2000................ In Vivo: assessment of DE produced lesions in DE generated from light-
mutant frequency and DNA and was mutagenic duty diesel engine
mutation spectra in lung in rat lung. Concentration of
following 4-wk exposure suspended particulate
to 1 or 6 mg/m3 DE, matter (SPM) measured,
transgenic rat 11 PAHs and nitrated
inhalation model used. PAHs identified and
quantitated in SPM.
Van Zijverden et al., 2000....... In Vivo: assessment of DPM skew immune response DPM, carbon black
immuno-modulating toward T helper 2 (Th2) particles (CBP) and
capacity of DPM, carbon side, and may silica particles (SIP)
black, and silica facilitate initiation used.
particles, mouse model of allergy. DPM donated by Nijmegen
used (sc injection into University, CBP and SIP
hind footpad). purchased from
BrunschwichChemie and
Sigma Chemical Co.,
respectively.
Vincent et al., 2001............. In Vivo: assessment of Increases in endothelin - Diesel soot, carbon
cardiovascular effects 1 and -3 (two black and urban air
following 4-hr exposure vasoregulators) particulates used.
to 4.2 mg/m3 diesel following ambient urban Diesel soot purchased
soot, 4.6 mg/m3 carbon particulates and diesel from NIST, carbon black
black, or 48 mg/m3 soot exposure. donated by University
ambient urban Small increases in blood of California, urban
particulates, rat pressure following air particulates
inhalation model used. exposure to ambient collected in Ottawa.
urban particulates.
Walters et al., 2001............. In Vivo: assessment of Dose and time-dependent DPM, PM, and coal fly
airway reactivity/ changes in airway ash used.
responsiveness, and BAL responsiveness and DPM purchased from NIST,
cells and BAL cytokines inflammation following PM collected in
following exposure to exposure to PM. Baltimore, and coal fly
0.5 mg/mouse aspirated Increase in BAL ash obtained from
DPM, ambient PM, or coal cellularity following Baltimore power plant.
fly ash. exposure to DMP, but
airway reactivity/
unchanged.
[[Page 48693]]
Whitekus et al., 2002............ In Vitro: assessment of Thio antioxidants (given DE generated from light-
ability of six as a pre-treatment) duty diesel engine, DPM
antioxidants to inhibit adjuvant collected, dissolved in
interfere in DPM- effects of DPM in the saline, and
mediated oxidative induction of OA aerosolized.
stress, cell cultures sensitization.
used.
In Vivo: assessment of
sensitization to OA and/
or DPM and possible
modulation by thiol
antioxidants, mouse
inhalation model used.
----------------------------------------------------------------------------------------------------------------
*Key:
(A) immunological and/or allergic reactions.
(B) inflammation.
(C) mutagenicity/DNA adduct formation.
(D) Induction of free oxygen radicals.
(E) airflow obstruction.
(F) impaired clearance.
(G) reduced defense mechanisms.
(H) adverse cardiovascular effects.
Table VI-9.--Review Articles on Toxicological Effects of DPM Exposure, 2000-2002
----------------------------------------------------------------------------------------------------------------
Authors, Year Description Conclusions Agent(s) of toxicity
----------------------------------------------------------------------------------------------------------------
ILSI Risk Science Institute Review of rat inhalation No overload of rat lungs Poorly soluble
Workshop Participants, 2000. studies on chronic at lower lung doses of particles, nonfibrous
exposures to DPM and to DPM and no lung cancer particles of low acute
other poorly, soluble hazard anticipated at toxicity and not
nonfibrous particles of lower doses. directly genotoxic
low acute toxicity that (PSPs)
are not directly
genotoxic.
Nikula, 2000..................... Review of animal Species differences in DE, carbon black,
inhalation studies on pulmonary retention titanium dioxide, talc
chronic exposures to DE, patterns and lung and coal dust
carbon black, titanium tissue responses
dioxide, talc and coal following chronic
dust. exposure to DE.
Oberdoerster, 2002............... In Vivo: review of High-dose rat lung Fibrous particles, and
toxicokinetics and tumors produced by nonfibrous particles
effects of fibrous and poorly soluble that are poorly soluble
nonfibrous particles. particles of low and have low
cytotoxicity (e.g., cytotoxicity (PSP)
DPM) not appropriate
for low-dose
extrapolation (to
humans); lung overload
occurs in rodents at
high doses.
Veronesi and Oortigiesen, 2001... In Vitro: review of nasal Pulmonary receptors PM: residual oil fly
and pulmonary stimulated/activated by ash, woodstove
innervation (receptors) PM, leading to emissions, volcanic
and pulmonary responses inflammatory responses. dust, urban ambient
to PM, mainly BEAS cells particulates, coal fly
and sensory neurons used. ash, and oil fly ash.
----------------------------------------------------------------------------------------------------------------
* Key:
(A) immunological and/or allergic reactions.
(B) inflammation.
(C) mutagenicity/DNA adduct formation.
(D) Induction of free oxygen radicals.
(E) airflow obstruction.
(F) impaired clearance.
(G) reduced defense mechanisms.
(H) adverse cardiovascular effects.
VII. Feasibility
A. Background on Feasibility
Section 101(a)(6)(A) of the Federal Mine Safety and Health Act of
1977 (Mine Act) requires the Secretary of Labor to establish health
standards which most adequately assure, on the basis of the best
available evidence, that no miner will suffer material impairment of
health or functional capacity over his or her working lifetime. Such
standards must be based upon:
Research, demonstrations, experiments, and such other
information as may be appropriate. In addition to the attainment of
the highest degree of health and safety protection for the miner,
other considerations shall be the latest available scientific data
in the field, the feasibility of the standards, and experience
gained under this or other health and safety laws. Whenever
practicable, the mandatory health or safety standard promulgated
shall be expressed in terms of objective criteria and of the
performance desired. (Section 101(a)(6)(A)).
The legislative history of the Mine Act states:
This section further provides that ``other considerations'' in
the setting of health standards are ``the latest available
scientific data in the field, the feasibility of the standards, and
experience gained under this and other health and safety laws.''
While feasibility of the standard may be taken into consideration
with respect to engineering controls, this factor should have a
substantially less significant role. Thus, the Secretary may
appropriately consider the state of the engineering art in industry
at the time the standard is promulgated. However, as the circuit
courts of appeals have recognized, occupational safety and health
statutes should be viewed as ``technology-
[[Page 48694]]
forcing'' legislation, and a proposed health standard should not be
rejected as infeasible ``when the necessary technology looms on
today's horizon''. AFL-CIO v. Brennan, 530 F.2d 109 (3d Cir. 1975);
Society of Plastics Industry v. OSHA, 509 F.2d 1301 (2d Cir. 1975),
cert. denied, 427 U.S. 992 (1975). Similarly, information on the
economic impact of a health standard which is provided to the
Secretary of Labor at a hearing or during the public comment period,
may be given weight by the Secretary. In adopting the language of
[this section], the Committee wishes to emphasize that it rejects
the view that cost benefit ratios alone may be the basis for
depriving miners of the health protection which the law was intended
to insure. S. Rep. No. 95-181, 95th Cong. 1st Sess. 21 (1977).
Though the Mine Act and its legislative history are not specific in
defining feasibility, the courts have clarified the meaning of
feasibility. The Supreme Court, in American Textile Manufacturers'
Institute v. Donovan (OSHA Cotton Dust), 452 U.S. 490, 508-509 (1981),
defined the word ``feasible'' as ``capable of being done, executed, or
effected.''
In promulgating standards, hard and precise predictions from
agencies regarding feasibility are not required. The ``arbitrary and
capricious test'' is usually applied to judicial review of rules issued
in accordance with the Administrative Procedures Act. The legislative
history of the Mine Act indicates that Congress explicitly intended the
``arbitrary and capricious test'' be applied to judicial review of
mandatory MSHA standards. ``This test would require the reviewing court
to scrutinize the Secretary's action to determine whether it was
rational in light of the evidence before him and reasonably related to
the law's purposes.'' S. Rep. No. 95-181, 95th Cong., 1st Sess. 21
(1977).
Thus, MSHA must base its predictions on reasonable inferences drawn
from existing facts. In order to establish the economic and
technological feasibility of a new rule, an agency is required to
produce a reasonable assessment of the likely range of costs that a new
standard will have on an industry, and the agency must show that a
reasonable probability exists that the typical firm in an industry will
be able to develop and install controls that will meet the standard.
B. Technological Feasibility
At this stage of the rulemaking, MSHA concludes that a permissible
exposure limit of 308 micrograms of EC per cubic meter of air
(308EC [mu]g/m\3\) is technologically feasible for the metal
and nonmetal underground mining industry. Courts have ruled that in
order for a standard to be technologically feasible an agency must show
that modern technology has at least conceived some industrial
strategies or devices that are likely to be capable of meeting the
standard, and which industry is generally capable of adopting. United
Steelworkers of America, AFL-CIO-CLC v. Marshall, (OSHA Lead) 647 F.2d
1273 (D.C. Cir. 1981) cert. denied, 453 U.S. 918 (1981) (citing
American Iron and Steel Institute v. OSHA, (AISI-I) 577 F.2d 825 (3d
Cir. 1978) at 834; and, Industrial Union Dep't., AFL-CIO v. Hodgson,
499 F.2d 467 (D.C. Cir.1974)). The existence of general technical
knowledge relating to materials and methods which may be available and
adaptable to a specific situation establishes technical feasibility. A
control may be technologically feasible when Aif through reasonable
application of existing products, devices or work methods with human
skills and abilities, a workable engineering control can be applied''
to the source of the hazard. It need not be an ``off-the-shelf''
product, but ``it must have a realistic basis in present technical
capabilities.'' (Secretary of Labor v. Callanan Industries, Inc.
(Noise), 5 FMSHRC 1900 (1983)).
The Secretary may also impose a standard that requires protective
equipment, such as respirators, if technology does not exist to lower
exposures to safe levels. See United Steelworkers of America, AFL-CIO-
CLC v. Marshall, (OSHA Lead) 647 F.2d 1164.
MSHA has established that technology is available that can
accurately and reliably measure miners' exposures to DPM in all types
of underground metal and nonmetal mines. MSHA intends to sample miners'
exposures by using a respirable dust sampler equipped with a
submicrometer impactor and analyze samples for the amount of elemental
carbon using the NIOSH Analytical Method 5040, or any other method that
NIOSH determines gives equal or improved accuracy, as stated in
existing Sec. 57.5061(b) and in this proposed rule.
MSHA is changing the surrogate that it uses to measure DPM
exposures from total carbon (TC) to elemental carbon (EC). This change
will avoid interferences associated with organic carbon that could
collect on the filter and increase the likelihood of contaminating the
sample with OC from non-diesel sources. MSHA agreed to propose this
change as dictated by the DPM Settlement Agreement and the entire
mining community supports this change.
Control mechanisms also exist that are capable of reducing DPM
exposures to the interim PEL of 308 micrograms in all types of
underground metal and nonmetal mines. MSHA believes that mine operators
will choose from various control options that are currently available,
including diesel particulate filter (DPF) systems, ventilation
upgrades, oxidation catalytic converters, alternative fuels, fuel
aditives, enclosures such as cabs and booths, improved maintenance
procedures, newer engines (less DPM emitting), and various work
practices and administrative controls. MSHA has given the mining
industry flexibility in selecting DPM control options that best suit
the mine operator's specific needs.
Based on the current information in the rulemaking record, MSHA
concludes that it has a technologically feasible measurement method
that operators and the Agency can use to accurately determine if
miners' exposures exceed the limit. Both control mechanisms and the DPM
sampling method are discussed elsewhere in this preamble. MSHA believes
that the proposed standard would adequately address feasibility issues
in one of two ways:
(1) Pursuant to Sec. 57.5060(a) and (d) of the proposed rule. If
MSHA determines that feasible engineering and administrative controls
are being installed, used, and maintained and still do not reduce a
miner's exposure to the limit, mine operators would be required to
supplement controls with a respiratory protection program; or,
(2) Mine operators may apply to the MSHA district manager for
approval for an extension of time in which to reduce miners' exposures
to the DPM limit. MSHA is not proposing any maximum limit on the number
of extensions an operator may have, since MSHA's decision hinges upon
feasibility.
The proposal permits operators greater flexibility in complying
with the DPM limit, contrary to the existing prohibition against using
administrative controls and respiratory protection. Mine operators who
need on-site technical assistance should contact the respective MSHA
district manager for assistance. MSHA will continue to assist mine
operators in special mining situations that could affect the successful
use of DPM filters.
Section IV above contains the executive summary of the 31-Mine
Study. As that section explains, the technical feasibility analyses in
the 31-Mine Study were based on the highest DPM sample result obtained
at each
[[Page 48695]]
mine and on all major DPM emission sources at each mine in addition to
spare equipment. The study found that five mines were already in
compliance with the interim concentration limit, and another two mines
were already in compliance with the existing lower, final concentration
limit.
MSHA predicted that eleven of the 31 mines could achieve compliance
with both limits through installation of DPM filters alone. Ventilation
upgrades were specified for only 5 of the 31 mines in this study, and
then only to achieve the final concentration limit. MSHA projected that
compliance with the interim and final concentration limits could be
achieved without requiring major ventilation installations such as new
main fans and repowering main fans. In the existing standard, the
agency based its feasibility projections on an average DPM
concentration level of over 800 [mu]g/m\3\. MSHA believes that miners'
exposures are now much lower, probably as a result of the introduction
of clean engines, better maintenance, and the elimination of
interferences as confirmed by MSHA's compliance assistance baseline
sampling.
MSHA collected baseline samples at most underground mines with
diesel powered equipment. Samples were collected in the same manner as
MSHA intends to sample for enforcement under the proposed rule. MSHA
found the average exposure (based on EC x 1.3) in the baseline sampling
to be 222 [mu]g/m\3\ resulting in greater compliance feasibility with
the proposed rule.
In spite of the concentrations observed in the 31-Mine Study, the
industry parties in the litigation continued to stress that compliance
with the existing standard was infeasible in that DPF systems could not
be retrofitted properly and could not effectively achieve regeneration.
Some operators also noted that they experienced difficulty in ordering
and obtaining DPF systems. MSHA could not confirm these statements, but
during the 31-Mine Study, the Agency did not find that mine operators
were using filtration devices. Moreover, few mine operators actually
contacted MSHA to ask for compliance assistance visits, in spite of the
Agency's repeated offers to help. Once MSHA initiated its comprehensive
compliance assistance work at underground mine sites, the Agency found
that most mines did not have complete information on the available
control technologies. Accordingly, MSHA stated in its final report on
the 31-Mine Study regarding feasibility:
Compliance with both the interim and final concentration limits
may be both technologically and economically feasible for metal and
nonmetal underground mines in the study. MSHA, however, has limited
in-mine documentation on DPM control technology. As a result, MSHA's
position on feasibility does not reflect consideration of current
complications with respect to implementation of controls such as
retrofitting and regeneration of filters. MSHA acknowledges that
these issues influence the outcome of feasibility of controls. The
agency is continuing to consult with NIOSH, industry and labor
representatives on the availability of practical mine worthy filter
technology.
Since this finding, however, MSHA and NIOSH have been working with
the metal and nonmetal underground mining community and equipment
manufacturers to continually refine and improve application of existing
DPM control technology. The Agency has made considerable strides in
resolving mine operators' concerns with the mine worthiness of DPF
systems.
During data collection for the 31-Mine Study, mine operators also
questioned the performance of the SKC sampler, especially in light of
modifications to it. Additionally, some commenters requested that MSHA
revise its internal sampling methodology and analysis for inspectors
and laboratory personnel.
MSHA disagrees. One of the objectives of the 31-Mine Study was to
examine the performance of the SKC sampler. The Agency is satisfied
with the performance of the SKC cassette in collecting DPM while
avoiding mineral dust. NIOSH's laboratory and field data show that the
SKC cassette collected DPM efficiently. Under a side protocol of the
31-Mine Study, MSHA tested the efficiency of the SKC cassette in
avoiding mineral dust at four mines. In these tests, no mineral dust
was measured on the filters of the SKC samplers. This finding was
confirmed by NIOSH laboratory tests. However, NIOSH discovered that in
many cases, the DPM deposit area was irregular in shape, and the shapes
varied among samples. Since the DPM deposit area is used to calculate
carbon concentrations attributed to DPM, the varied shapes can cause an
error in determining DPM concentrations. With the cooperation of MSHA
and the technical recommendations and extensive experimental
verification by NIOSH, SKC was able to modify the cassette design to
produce a consistent and regular DPM deposit area, satisfactorily
resolving the problem.
The fact that the deposit area was assumed constant when in fact
there were variations in the boundary (shape) and area of deposit of
the SKC cassette samples taken in the 31-Mine Study affects only the
reported concentrations of the carbon values (EC, OC, and TC) because
deposit area is used in concentration calculation. The results of the
inter-laboratory and intra-laboratory studies that compared the
analysis of the punches of those (or any) filters from the SKC cassette
are unaffected for two reasons: (1) The deposit area does not enter
into the calculations (surface densities of carbon in ug/cm \2\ were
compared), and (2) the punches were taken from filters inside the
boundary of the area of deposits, where the deposits were uniform.
In their comments to the ANPRM, mine operators continued to
emphasize the need for more research on control technology.
Additionally, NIOSH commented:
In conclusion, various manufacturers offer the particulate
filters for diesel engines rated from 15 to several hundred hp.
Although on the market for more than a decade, DPF systems have been
only sporadically deployed and tested on underground mining
vehicles. The DEEP-sponsored evaluation tests at Noranda BM&S and
INCO Stobie Mines are based on our knowledge, the best organized
attempts to evaluate DPFs in the underground environment. The
results from these tests reveal that the DPF systems that have been
evaluated on heavy-duty vehicles powered by engines rated over 277
hp and on light duty vehicles powered by 50 hp engines offer
promising technology. However, this technology needs significant
additional evaluation and some possible re-engineering for
underground mining applications. In-use deficiencies, secondary
emissions, engine backpressure, DPF regeneration, DPF reliability
and durability are major issues requiring additional research and
engineering. In addition, it is been found that deployment of most
systems, particularly those which require active means of
regeneration, require major changes in miners' attitudes toward
engine and DPF maintenance. NIOSH's DEEP experienced showed that
emission-based engine maintenance, greater discipline on the part of
the vehicle operator, and better operational logistics (e.g.,
multiple locations of regeneration stations for a single vehicle)
are imperative for success of DPF technology.
To the contrary, the NIOSH comments in response to the ANPRM
include a summary of their experience with retrofitting existing diesel
powered equipment. NIOSH acknowledges that although diesel particulate
filters have been available to U.S. mines for many years, they have not
been extensively used and documented. NIOSH states that in-mine
experience with filters is limited, but NIOSH also related their
experience with the Diesel Emissions Evaluation Program (DEEP) in
Canada. NIOSH stated:
[[Page 48696]]
[The DEEP program] has shown that these filters have significant
potential for reducing DPM exposure of miners, but that there are
numerous technical and operational issues that need to be addressed
through research and in-mine evaluations before they can be readily
implemented on a broad-based scale in U.S. mines.
MSHA has found that most mine operators can successfully resolve
their implementation issues if they make informed decisions regarding
filter selection, retrofitting, engine and equipment deployment,
operations, and maintenance. The Agency recognizes that practical mine-
worthy DPF systems for retrofitting most existing diesel powered
equipment in underground metal and nonmetal mines are commercially
available and are mine worthy to effectively reduce miners' exposures
to DPM. MSHA also recognizes that installation of DPF systems will
require mine operators to work through technical and operational
situations unique to their specific mining circumstances. In view of
that, MSHA has provided comprehensive compliance assistance to the
underground metal and nonmetal mining industry.
Commenters to the ANPR responded to the question of changing a
diesel engine model to accommodate a control device by stating that
anything other than the original engine model is essentially
incompatible and would require prohibitive design engineering analysis
and implementation. MSHA agrees that it may not be feasible to change
engines on some diesel powered equipment. However, as engine
manufacturers develop cleaner engines over time, they are phasing out
older models and newer, cleaner engine models are available from the
same engine manufacturer. In some cases, the new engine models are
direct replacements for an older model. The benefits of retrofitting a
machine with a cleaner engine are better fuel economy, less DPM emitted
from the tailpipe, better lubrication systems, and better diagnostic
tools, especially with the electronic engines. A cleaner engine that
emits less DPM will deposit less DPM on the filter, thus permitting
more time between regeneration, especially in active regeneration
systems or combination active/passive regeneration systems.
Filter Workshops
Recently, government, labor and industry sponsored two workshops on
``Diesel Emissions and Control Technologies in Underground Metal and
Nonmetal Mines'' held in Cincinnati, Ohio, on February 27, 2003, and
Salt Lake City, Utah, on March 4, 2003. These workshops focused on
implementation of DPM control technologies capable of reducing DPM
exposures to particulate matter and gaseous emissions from diesel-
powered vehicles that are presently available to the underground metal
and nonmetal mining industry in this country. The workshops provided an
excellent forum for open discussion and the exchange of ideas and
experiences relative to the use of diesel powered equipment in
underground mines.
At the workshops, industry experts discussed issues pertaining to
the installation and use of DPFs in underground mines. Application of
technology and mine operators' experiences with using filters on their
diesel powered equipment are becoming more commonplace in the mining
industry since the promulgation of the DPM rule.
MSHA, NIOSH, and industry speakers presented their first-hand
experiences with the implementation and use of diesel particulate
filters in underground mines since promulgation of the existing DPM
rule. Major diesel filter manufacturers and vendors of control
technologies and engines also participated in the workshops.
NIOSH compiled a summary report to capture presentations, comments
and discussions rendered at the workshops, including comments offered
by industry representatives who shared their experiences with the
effectiveness of DPM filters. MSHA believes that NIOSH's account of the
workshops helps to demonstrate feasibility of control technology
measures that mine operators have found beneficial and effective. MSHA
mailed copies of the NIOSH report to mine operators covered by the
proposed rule. This information also is available on the NIOSH Diesel
List Server. At the workshops, the following information was discussed:
DPF Efficiency: Laboratory and field studies indicate that
filtration efficiency for elemental carbon is above 95% and perhaps is
as high as 99%.
MSHA worked with NIOSH at MSHA's laboratory to determine the
efficiency of several ceramic filters. MSHA ran steady state tests on
the dynamometer and collected DPM samples for NIOSH 5040 analysis. The
results of the filter tests showed efficiency results close to 99% for
elemental carbon. NIOSH commented:
The INCO project includes two Kubota M5400 tractors powered by
Kubota F2803B 50 hp engines [Stachulak 2002]. Both are fitted with
actively regenerated DPFs that have a silicon carbide (SiC) filter
core. The SiC cores come from the same manufacturer; the DPF systems
are supplied by different manufacturers. The filtration efficiency
at the tailpipe is 99 percent for EC as determined by
NIOSH using the EchoChem Analytics PAS 2000 carbon particle
analyzer. One DPF system uses active on-board regeneration; electric
heating coils are integrated into the unit and the unit is plugged
into a regeneration controller mounted off board. The other unit is
an active off-board system in which the DPF is removed from the
vehicle and exchanged with the previously regenerated filter. The
soot-laden filter is placed in a regeneration station. Both vehicles
are assigned to ``special groups'' of individuals who ensure that
the regenerations are performed as needed.
MSHA stated in the preamble to the January 19, 2001 Final Rule that
filter efficiency for cordierite and silicon carbide media used in many
DPF systems is 85% and 87% respectively for diesel DPM. These
efficiencies were based on whole diesel particulate as collected per
part 7, subpart E specifications for measuring DPM. The mining industry
has expressed concern that laboratory results do not reflect the real
world in both duty cycle and operational environment, so the Metal and
Nonmetal Diesel Partnership and MSHA will conduct a set of in-mine
tests before mid-2003.
DPF Selection: To use DPF systems successfully, mine operators must
do their homework prior to ordering DPF systems. It is critical for
filter performance and efficiency to match the filters to the diesel
powered equipment and consider how the equipment is to be used in the
underground mine. Mine operators should assume that every application
is unique.
Following promulgation of the existing DPM rule, most mine
operators were unaware that filter selection involves consideration of
these factors. Therefore, in February 2003, MSHA and NIOSH posted on
their web sites a comprehensive compliance assistance tool titled ``A
DPM Filter Selection Guide for Diesel Equipment In Underground Mines''
(Filter Selection Guide). The guide provides mine operators with
detailed step-by-step considerations in selecting DPF system compatible
with the specific equipment. Also, the Filter Selection Guide provides
information on modifications and adjustments to diesel powered
equipment that mine operators may have to make to successfully apply
DPF systems.
Mine operators should start by making certain that they are
properly maintaining their engines and not consuming excessive amounts
of crankcase oil. The mine operator may then obtain exhaust temperature
logs or traces for several shifts, and use these
[[Page 48697]]
traces to select the DPF systems with the regeneration options that
will work for that piece of equipment. Exhaust temperature traces can
be analyzed by mine personnel or given to several DPF suppliers to use
to provide the operator with options.
Exhaust temperatures govern the DPF regeneration options. These
options are provided in the Table VII-1.
Table VII-1.--DPF Regeneration Options
------------------------------------------------------------------------
DPF system (media
Temperature that the exhaust consists of
exceeds 30% of the time, cordierite or Comments
degrees C silicon carbide
ceramic)
------------------------------------------------------------------------
550.............. Uncatalyzed media... Rarely, if ever,
occurs.
390-420.......... Base metal catalyzed No increase in NO2.
cordierite.
340.............. Lightly platinum Special provisions
catalyzed ceramic must be made to
with CDT fuel ensure additive is
additive. always present in
fuel and that
equipment w/o DPFs
cannot be fueled
with additive-
containing fuel. No
increase in NO2.
325.............. Platinum catalyzed Lab results indicate
ceramic. significant NO to
NO2 conversion;
field results are
mixed.
Any temperature Active (Manually) Insufficient exhaust
below 325. regenerated system. temperature to
support spontaneous
regeneration during
shift. DPFs are
regenerated in
place with
equipment off-duty
or DPF is swapped
out.
------------------------------------------------------------------------
As Table VII-1 shows, a DPF system will function successfully at or
above an exhaust gas temperature specified by the manufacturer's
regeneration temperature, that is, an active regenerating system will
work at all exhaust temperatures, and a platinum catalyzed system at
any temperature above 325[deg]C. However, these exhaust gas
temperatures must be achieved at least 30% of the time during the day
to be sufficient for passive regeneration. In addition, the tune of the
engine will also be a factor for proper regeneration. If an engine goes
out of tune and begins to emit higher DPM concentrations in the
exhaust, the exhaust backpressure may increase more quickly. Therefore,
it is recommended that mine operators install backpressure devices on
machines equipped with filters in order to properly monitor the
condition of the filter and regeneration of the filter.
Table VII-1 also provides information in the ``Comments'' column on
the effect of the filters coated with a catalyst on NO2
emissions. MSHA has tested in their laboratory the types of filters
listed and has posted on its Web site a list of the filters that can
cause NO2 increases from the engine and those catalytic
formulations that do not significantly increase NO2.
NO2 is formed from NO in the engine's exhaust in the
presence of the catalyst. This reaction occurs at exhaust gas
temperatures at approximately 325[deg]C. This temperature is also the
temperature at which the platinum catalyst will allow for passive
regeneration. Filter manufacturers have normally wash-coated their
filters with large amounts of platinum to make sure that the filters
will regenerate. This large concentration of platinum, in combination
with longer retention time of the exhaust gas in the filter, results in
the formation of NO2. Manufacturers have been looking at
wash-coat formulations containing less platinum loading to lower the
NO2 effects. Catalytic converters are also wash-coated with
platinum, however, the loading used on catalytic converters is lower
than ceramic filters. Due to faster movement of the exhaust gas through
the catalytic converter compared to the ceramic filter, the effect of
NO2 increase is minimized.
MSHA is not aware of overexposures to NO2 with the use
of those catalyzed traps that MSHA has identified. MSHA issued a
Program Information Bulletin (PIB 02-04, May 31, 2002) which alerted
mine operators that catalyzed traps identified on our Web site could
increase NO2. Mine operators were advised to conduct
sampling for NO2 when these filters were used to ensure
miners' are not overexposed or that the filters were causing a general
increase of NO2 in the mine's ambient environment. Mine
operators who use catalyzed filters (which have the potential to
increase NO2) should have ventilation systems that are able
to remove or dilute the NO2 to a non-hazardous
concentration. However, operators must be aware of localized areas
where NO2 could build up more quickly and create a health
hazard for exposed miners.
As discussed in the Greens Creek report, the use of catalyzed
filters on those machines used in the study did not indicate any
substantial increase in NO2. MSHA is continuing to work with
filter manufacturers to evaluate catalytic formulations on
NO2 generation from the exhaust.
Active regeneration systems discussed below are normally not
catalyzed which would then not produce an increase in NO2.
As stated above, NO2 is generated when exhaust gas
temperatures are normally high enough for passive regeneration. If the
filter can passively regenerate, then there is a potential for
increases in NO2 emissions.
Table VII-2.--Scenarios for Active Regeneration
----------------------------------------------------------------------------------------------------------------
Regenerating controller
System name Regenerating location location Comments
----------------------------------------------------------------------------------------------------------------
On-board-On-board................ On Equipment............. On Equipment............ Requires source of
electric power,
normally 440 or 480
VAC.
On-board-Off-board............... On Equipment............. Designated and fixed- Requires equipment to
location. come to a specific
regeneration site.
[[Page 48698]]
Off-board........................ Off equipment............ Fixed-location.......... DFPs are exchanged and
must be small enough to
be handled by one
person. Increases
number of DPFs needed.
On-board fuel burner............. On-equipment............. On-equipment during System is complex yet
operation. provides advantages of
operating during
equipment use;
manufacture has been
discontinued.
----------------------------------------------------------------------------------------------------------------
Scenarios for active regeneration systems are listed in Table VII-
2. The first two systems listed in Table VII-2 may require sufficient
machine down time for regeneration, which is usually about one hour
between shifts. Also, the equipment should be parked at a designated
location during the regeneration period. MSHA recognizes that presently
in some mines, production equipment is not brought to a specific
location at the end of a shift. At mines where this occurs, mine
operators may need to make changes to accommodate such DPF regeneration
designs. Alternatively, mine operators may choose to have the equipment
operator remove the DPF at the end of each shift and have the next
operator replace it with a regenerated unit at the start of the shift.
In short, mine operators must plug in the regeneration system at the
end of the shift, or DPFs must be transported from the regeneration
area to the equipment location. Multiple filters may be installed on a
machine in the place of one filter in order to decrease the size and
weight of the filters.
Under certain circumstances, some passive DPF systems have
exhibited marginal regeneration. This is due to the fact that the duty
cycle exhaust temperature is such that some but not all of the DPM is
removed during the normal work shift. Slowly the DPM builds up until
the DPF must be regenerated manually. In some instances, this needs to
be done every 250 hours which would coincide with the regular
preventive maintenance cycle for diesel powered equipment.
Achieving a long service life: The key to achieving a long service
life from any DPF is to monitor and strictly adhere to exhaust back
pressure limits and taking action appropriately. Passive regenerating
systems are especially sensitive to equipment duty cycle. A change in
duty cycle may reduce exhaust temperatures to a point that regeneration
does not spontaneously occur. It is crucial that prompt attention is
given to this situation and it is remedied before exhaust backpressures
even reach the specified backpressure limit. Continuing to operate with
an increasing exhaust backpressure will lead to overloading the DPF
with soot. When regeneration is initiated, the large mass of soot may
create temperatures hot enough to crack or melt the filter element,
thus compromising the filter's efficiency. A similar scenario applies
to active systems. Failure to timely regenerate the filter will cause
increases in back pressure during a production shift which, if
continued, will cause loss of engine power and may invalidate engine
warranties.
Thermal runaway may also occur during manual regeneration. Because
of the build up of ash, an unburnable component of diesel soot arising
from burning lubrication oil, the baseline back pressure of any DPF
will rise slowly. Approximately every 1,000 hours, the DPF should be
cleaned of the ash following the manufacturer's procedure.
Engine malfunctions and effects on DPF: Normally in mining, engine
malfunctions are indicated by excessively smoky exhaust. That indicator
will not occur with DPF systems. Malfunctions such as excessive soot
emissions, intake air restriction, fouled injector, and over-fueling,
may result in an abnormal rise in back pressure in systems that do not
spontaneously regenerate. Also, these conditions could lead to abnormal
changes in back pressure in passive systems because the malfunction may
raise exhaust temperatures causing the excess soot to be burned off.
These malfunctions may be detected during the usual 250-hour
maintenance and emissions checks conducted upstream of the DPF using
carbon monoxide (CO) as an indicator.
The other major filter malfunction is excessive oil consumption
that is sometimes associated with blue smoke that could be masked by
the performance of the DPF. However, excessive oil consumption leads to
a rapid increase in baseline backpressure due to ash accumulation.
Excessive oil consumption can be detected if records are kept on oil
usage.
Detecting malfunctioning DPF: As noted above, the DPF can be
damaged mainly by thermal events such as thermal runaway. Shock,
vibration, or improper ``canning'' of the filter element in the DPF can
also lead to leaks around the filter element. A Bacharach/Bosch smoke
spot test can be used to verify the integrity of a DPF. Smoke spot
numbers below ``1'' indicate a good filter; smoke numbers above ``2''
indicate that the DPF may be cracked or leaking. Smoke spot and CO
tests during routine 250 hour preventative maintenance is a good
diagnostic practice. Note that although a smoke spot number above ``2''
may indicate a cracked or leaking filter, such a result does not
necessarily mean the filter has ``failed'' and is not functioning
adequately. In MSHA evaluations of DPF performance at the Greens Creek
mine, filters that tested with smoke numbers above ``2'' were still
shown to be over 90% effective in capturing elemental carbon, based on
subsequent NIOSH 5040 analysis of the smoke spot filters.
Some commenters have suggested that diesel particulate filters are
not a feasible DPM control option because they are not commercially
available for the full range of engine horsepowers used in underground
metal and nonmetal mining equipment, especially low horsepower units
(less than 50 hp) and high horsepower units (greater than 250 hp). MSHA
has found that suitable DPFs for engines of the horsepowers used in
underground metal and nonmetal mining equipment are commercially
available. The following discussion addresses low horsepower and high
horsepower applications, respectively.
Low horsepower engines ranging from around 5 horsepower to around
100 horsepower are frequently used in ancillary and support mining
equipment such as personnel transports, utility tractors, ``gators,''
fork lifts, pumps, welders, compressors, and similar equipment, both
mobile and stationary. The duty cycle of this type of equipment
[[Page 48699]]
is not sufficient to support passively controlled regeneration of a
DPF. Thus, either on-board or off-board active filter regeneration is
necessary.
In sizing an actively regenerated filter for these small horsepower
engines, the only significant selection criterion is the desired time
interval between active regenerations. For example, if the user wishes
to regenerate a filter no more often than once per day, then the filter
must have the capacity to store the maximum amount of soot generated by
the subject engine over the period of one day while maintaining
acceptable engine backpressure. If physical space to mount a filter is
limited, the smallest filter having adequate soot storage capacity at
the maximum acceptable backpressure would be selected. If space
constraints are not an issue, a larger capacity filter would also be
acceptable, with the larger size permitting a longer time interval
between regenerations.
As a point of reference, a once-per-day actively regenerated DPF
for a 60 hp personnel transport tractor operated for one shift per day
is about 20 inches long by about 10 inches in diameter, and such
filters are commercially available from multiple sources. If the same
filter is fitted to a 30 hp engine having the same duty cycle and
emission rate (expressed as g/bhp-hr), that filter will function just
as well, but the time interval between regenerations would roughly
double. Based on this DPF selection process, there is probably no lower
limit to the size engine that can be effectively filtered using any of
several commercially available active systems.
DPFs for low horsepower engines can also be provided by the
original equipment manufacturer (OEM) or distributor as standard or
optional equipment. An example is a Series 7 Toyota forklift equipped
with a 40 hp 1DZ-II diesel engine for which a DPF-II diesel particulate
filter is offered as an OEM or dealer-installed option. The DPF unit is
about 14-inches long and about 8-inches in diameter, and is mounted on
the rear of the forklift body.
Regarding high horsepower applications of DPF systems, for purposes
of this discussion, ``high'' horsepower is meant to include engines of
250 horsepower and higher because this is the horsepower range
addressed by the commenter. Engines of this size would typically be
installed on production equipment such as loaders and haulage trucks
and are commercially available from several manufacturers.
There are two approaches to filtering diesel particulate emissions
that can be implemented on high horsepower engines using current
commercially available DPF units: large capacity single unit DPFs; and
multiple DPFs that are either manifolded to the same exhaust pipe, or
separate DPFs that are provided on each side of a dual exhaust system.
An example of a large capacity single unit DPF system is the
Engelhard model 9121A 15-inch long by 15-inch diameter Pt-catalyzed
filters installed on the LHD and haulage trucks that were the subject
of MSHA's compliance assistance diesel emissions tests at the Greens
Creek mine. The LHD and all three haulage trucks were equipped with the
same MSHA Approved 12.7 L engines rated at 475 hp at 2100 rpm. The LHD
engine was derated to 300 hp, but this value still exceeds the
commenter's threshold level of concern of 250 hp, and the truck engines
were generating the full 475 hp. These DPFs passively regenerated on
both the loader and haulage trucks, and the emission testing
demonstrated filter efficiencies of greater than 90%.
The other approach to filtering high horsepower engines is to
provide multiple filters. When an engine's exhaust is routed through a
single exhaust pipe, the exhaust can be split into two parallel paths,
with each path being equipped with a filter. When an engine has a dual
exhaust system (i.e. separate exhaust pipes on either side of the
engine, which is the most common arrangement on high horsepower
engines), a DPF can be fitted to each exhaust pipe. This approach
actually simplifies a DPF installation on an engine with dual exhausts,
as installing a single filter would require modification of the exhaust
system to join together the dual exhausts into a single exhaust pipe
upstream of the filter. On underground equipment where space is at a
premium, it may be easier to install two smaller filters than to find a
space large enough to install one large filter.
Depending on the horsepower of an engine, space constraints, method
of filter regeneration, and other factors, it may be necessary to split
an engine's exhaust into more than two parallel paths for DPF
installation. For example, each side of a dual exhaust system could be
split into two parallel paths to facilitate the installation of DPFs on
all four of the resulting exhaust pipes. There is no upper limit on the
horsepower of an engine that could be filtered with standard,
commercially available DPFs. For example, MSHA is aware of a stationary
diesel-powered generator station rated at about 12,000 hp that has been
filtered in this manner.
Although sizing a ceramic (SiC or cordierite) DPF is a rather
complicated process that must take into account consideration for
engine horsepower, engine DPM emissions (g/bhp-hr), duty cycle,
constraints on regeneration, and other factors, the ``rule-of-thumb''
starting point for most filter manufacturers is typically 8 cubic
inches of filter media volume per horsepower for an engine having a DPM
emission rate of 0.1 g/bhp-hr. Due to manufacturing complications for
larger units, the filter media is typically limited to a maximum size
of 15-inches long by 15-inches in diameter. These dimensions correspond
to a maximum of 330 hp per filter for an engine having an emission rate
of 0.1 g/bhp-hr. For cleaner engines like those used in the Greens
Creek mine testing, these dimensions correspond to a proportionally
larger horsepower engine.
If each side of a dual exhaust system is split only once, requiring
four separate DPFs, installation of 15x15 filters on each of the four
branches would adequately filter a 0.1 g/bhp-hr emission engine rated
at greater than 1,300 hp, which is larger than any engine currently
used in underground metal and nonmetal mining, or likely to be used in
the foreseeable future.
Importance of preventing exhaust leaks: Because the DPF is greater
than 95% effective in removing elemental carbon from the exhaust, it is
extremely important that the exhaust system upstream of the DPF be
leak-tight. Leaks will leave a shadow of soot and are thus self-evident
unless covered by insulation that disperses the leaking exhaust so that
no distinct soot shadow is produced. Flex-pipe joints should be
fastened securely using wide band clamps. Operators should not use flat
flanges with gaskets, but use tapered tongue and groove joints to
attain a positive seal.
Alternative Options
In addition to the feasibility of engineering control technology
that was discussed at the NIOSH workshops (low emission engines,
maintenance, fuels, and DPFs), MSHA believes that enhancing ventilation
and enclosing miners in cabs or other filtered areas also are effective
engineering controls for significantly reducing DPM exposures.
Administrative controls can effectively reduce miners' exposure to
DPM. These include such practices as: reducing diesel engine idling
time, reducing lugging of engines, designating certain areas ``off
limits'' for operating diesel equipment, and establishing speed limits
and one way travel.
[[Page 48700]]
MSHA acknowledges that depending upon the circumstances in a
particular underground mine, some mine operators may face feasibility
challenges implementing current DPM control methods. These operators
should contact the MSHA district manager for compliance assistance.
Several commenters expressed the view that ventilation system
upgrades, though potentially effective in principle, would be
infeasible to implement for many mines. Specific problems that could
prevent mines from increasing ventilation system capacity include
inherent mine design geometry and configurations (drift size and
shape), space limitations, and other external prohibitions, as well as
economic considerations.
MSHA acknowledges that ventilation system upgrades may not be the
most cost effective DPM control for many mines, and for others,
ventilation upgrades may be entirely impractical. However, at many
other mines, perhaps the majority of mines affected by this rule,
ventilation improvements would be an attractive DPM control option,
either implemented by themselves or in combination with other types of
controls.
At many high-back room-and-pillar stone mines, MSHA has observed
ventilation systems that are characterized by (1) Inadequate main fan
capacity (or no main fan at all); (2) ventilation control structures
(air walls, stoppings, curtains, regulators, air doors, and brattices,
etc.) that are poorly positioned, in poor condition, or altogether
absent; (3) free standing booster fans that are too few in number, of
too small a capacity, and located inappropriately; and, (4) no
auxiliary ventilation for development ends (working faces). At some
mines, the ``piston effect'' of trucks traveling along haul roads
underground provides the primary driving force to move air.
Often, the result of these deficiencies is a ventilation system
that provides insufficient dilution of airborne contaminants, short
circuiting, and airflow direction and volume controlled only by natural
ventilation. These systems are barely adequate (and sometimes
inadequate) for maintaining acceptable air quality with respect to
gaseous pollutants (CO, CO2, NO, NO2,
SO2, etc.), and are totally inadequate as stand-alone
controls for maintaining acceptable DPM levels.
Mines experiencing these problems could benefit greatly from
upgrading main, booster, and/or auxiliary fans, along with the
construction and maintenance of effective ventilation control
structures. During DPM compliance assistance visits to several stone
mines, MSHA has observed mine operators beginning to implement limited
ventilation system upgrades, such as the addition of booster fans,
brattice lines, and auxiliary ventilation in development ends, along
with replacing older, high-polluting engines with newer, low-polluting
models. MSHA believes that such ventilation upgrades, along with the
replacement of as few as one to three engines may be sufficient for
many stone mines to achieve compliance with the interim DPM limit.
Deep multi-level metal mines have entirely different geometries and
configurations from high-back room-and-pillar stone mines. They
typically require highly complex ventilation systems to support mine
development and production. These systems are professionally designed,
they require large capital investments in shafts, raises, control
structures, fans, and duct work, and they are costly to maintain and
operate. At these mines, ventilation system costs provide a major
economic incentive to operators to optimize system design and
performance, and therefore, there are typically few if any feasible
upgrades to main ventilation system elements that these mines have not
implemented already.
Despite these built-in incentives, however, MSHA has observed
aspects of ventilation system operation at those types of mines that
can be improved, usually relating to auxiliary ventilation in stopes.
Auxiliary fans are sometimes sized inappropriately for a given
application, being either too small (not enough air flow) or
incorrectly placed (causing recirculation). Auxiliary fans that are
poorly positioned draw a mixture of fresh and recirculated air into a
stope. Auxiliary fans are sometimes connected to multiple branching
ventilation ducts, so that the air volume reaching a particular stope
face may be considerable less than the fan is capable of delivering.
Perhaps most often, the ventilation duct is in poor repair, was
installed improperly, or has been damaged by blasting or passing
equipment to the extent that the volume of air reaching the face is
only a tiny fraction of that supplied by the fan. MSHA believes that
these, and similar problems, exist at many mines, even if the main
ventilation system is well designed and efficiently operated.
Optimized auxiliary ventilation system performance alone, as one
commenter noted, will not necessarily insure compliance with the DPM
interim limit. Auxiliary ventilation systems simply direct air to a
stope face so that the DPM generated within the stope can be diluted
and carried back to the main ventilation air course. If air is already
heavily contaminated with DPM when it is drawn into a stope by the
auxiliary system, as could happen at mines employing series or
cascading ventilation, the auxiliary system's ability to dilute newly-
generated DPM is diminished.
In these situations, the intake to the auxiliary system must be
sufficiently free of DPM to achieve the desired amount of dilution,
requiring implementation of effective DPM controls upstream of the
auxiliary system intake. Such upstream controls might include a variety
of approaches, such as DPM filters, low-polluting engines, alternative
fuels, and various work practice controls, as well as main ventilation
system upgrades at the few mines where they might be feasible. Toward
the return end of a series or cascading ventilation system, if the DPM
concentration of the auxiliary system intake is still excessive, other
engineering control options would include enclosed cabs with filtered
breathing air on the equipment that operates within the stope, or
remote control operation of the equipment in the stope to remove the
operator from the stope altogether. Some commenters stated that
feasibility was extensively reviewed in the existing rulemaking. These
commenters noted that MSHA already determined that feasibility
established for the existing rule must be presumed feasible until
proven otherwise. In response to these commenters, MSHA emphasizes that
since the agency is engaged in rulemaking that involves changing the
surrogate, the DPM limit, as well as the hierarchy of controls, the
Agency must review its existing position on feasibility of compliance
for the mining industry. MSHA has done so in this preamble. Other
commenters stated that mine operators have attempted to purchase and
install DPM controls and they are either unavailable or, are neither
technically and economically feasible. One issue raised by the
commenters was the availability of filters for engines below 50 hp.
Filter manufacturers supply filters for all horsepower sizes. MSHA is
not aware of any gaps in filter availability. As stated at the recent
workshops, most filter vendors stated that they have experience
installing DPM filters on all horsepower size engines. However,
normally with smaller engines, it would be expected that these systems
would have to be regenerated with an active system. Again, MSHA is not
aware of any problems with an active system for
[[Page 48701]]
smaller engines. In regard to larger horsepower engines, again, at the
workshops filter vendors stated that most had experience with larger
horsepower engines. They referred to installations that were greater
than 500 hp. As stated by the manufacturers, this is normally
accomplished with multiple filters to accommodate the larger engines'
higher exhaust flow rates. Again, either passive or active regeneration
systems have been identified as being available for these large
engines.
As discussed elsewhere in this preamble, the work conducted at the
Greens Creek mine in Alaska showed that large horsepower engines, 475
hp used at this mine, could be equipped with ceramic filters and these
DPFs were regenerated through passive regeneration. A filter rotation
issue was identified at the beginning of this study, however, after
further discussions with the filter vendor, it was determined that the
problem was a manufacturing issue and was being worked out between the
mine and the vendor. Even with the observed cracks due to the rotation
of the filters, the results of tests showed that the filters continued
to significantly reduce DPM from the engine, thus lowering the DPM in
the test area.
A commenter also related a filter scenario that failed. This was
reported as a cooperative effort between the machine manufacturer,
engine manufacturer, and filter manufacturer for selection of a filter
system for a 300 hp truck. The commenter stated that with this group
working together, the filter system installed failed. MSHA was aware of
this situation and understands that the problem was related to
regeneration of the filter and not a filtration issue. MSHA believes
that even with this cooperation, a vital piece of information
concerning the duty cycle and exhaust gas temperatures generated from
this truck was not properly communicated to the parties involved. This
would lead to a failure where the system would have been set up to
regenerate through a passive method, but in actuality, the machine
needed an active system or active/passive system. As stated elsewhere,
accurate information on the duty cycle/exhaust gas temperature of a
vehicle is critical for successful filter installations. The condition
of the engine and backpressure monitoring is also essential in choosing
and installing a filter system.
As discussed previously in this preamble, MSHA and NIOSH developed
the filter guide which makes mine operators and machine manufacturers
aware of the issues that must be addressed to successfully engineer a
filter to work on a machine. MSHA believes that if mine operators and
equipment manufacturers utilize this guide, many of the problems
identified with regeneration would be eliminated.
Other commenters stated that the existing limits are not feasible
unless MSHA allows mine operators to use administrative controls and
personal protective equipment, both of which are prohibited under the
existing DPM rule. Consistent with the DPM settlement agreement, MSHA
proposes to require its long-standing hierarchy of controls for
engineering, administrative, and personal protective equipment. Some
commenters stated that if elemental carbon (EC) is used, periodic
diagnostic emission tests similar to those required under MSHA's
existing standards for underground coal mines at Sec. 75.1914(g)
should be required for metal and nonmetal underground mines in order to
compare emissions against an engine baseline to determine if elevated
organic carbon levels are actually DPM rather than an interferent.
These commenters also stated that OC and EC may not increase
proportionally in an engine that is in a state of deterioration.
Section 75.1914(g) for underground coal mines requires weekly
emission checks on the engine to determine the tune of the engine. The
CO concentration must be measured during a repeatable loaded engine
test, namely at torque stall. By measuring the CO on a weekly basis, a
baseline is established for each engine. Any changes to the baseline of
the CO concentration when the repeatable engine test is performed could
be an indication that the engine is out of tune. This could be the
result, for example, of a clogged intake air filter or a faulty
injector. Whereas MSHA agrees that this type of engine testing could be
useful as a diagnostic tool to determine the tune of the engine, MSHA
noted in its ANPRM as well as in this proposal that the scope of this
rulemaking is limited to the terms of the settlement agreement.
However, MSHA requests specific comments from the mining community as
to whether this test should be required in the final rule. Commenters
should include whether or not any aspects of the current provision at
Sec. 75.1914(g) should be adopted or revised as part of the final
rule.
It is well documented that an engine that is not in tune will emit
higher levels of gaseous emissions and DPM emissions. An engine that is
not tuned could have an immediate effect on miners' personal DPM
exposures. The same commenter stated that the out-of-tune engine could
be dismissed in the results of the ambient Method 5040 sampling as an
interferent instead of an increase in DPM. The effects of individual
engines would be very hard to localize with ambient testing. MSHA
agrees that maintenance procedures that could detect any increases in
exhaust emissions would aid in limiting miners' DPM exposures. The
Agency's current DPM standard at Sec. 57.5066 addresses both
maintenance and tagging of equipment for out-of-tune engines. Poor
engine performance will most likely result in black smoke that must be
the reported to the mine operator and promptly given attention by a
mechanic.
The Agency is aware of another diagnostic tool to determine the
effectiveness of a ceramic filter. In a diagnostic ``smoke test,'' a
sample of DPM is collected as a smoke dot on a filter paper and
visually compared against a colorimetric scale. The test would be
conducted while the diesel powered equipment is in a torque stall
condition, which is a repeatable, high engine load condition for making
this comparison. Normally, the raw exhaust before a filter would give a
black spot. A sample taken after the filter should be basically white,
indicating that the filter was working at its highest efficiency. Any
cracks or defects in a ceramic filter would give a darker, grayish to
black spot. This would be an indication to the mine operator of the
current condition of the filter and of possible filter deterioration.
Smoke dot tests were conducted at the Greens Creek mine as a part
of DPM compliance assistance activities at that mine. On one particular
filter, the smoke dot produced after the DPM filter appeared to be as
dark as the smoke dot before the DPM filter. Visual examination of the
DPM filter showed cracks along its outer edges. When quantitative
analysis of the dots was conducted using the NIOSH Method 5040
analysis, DPM filter efficiency was determined to be 92%. The
efficiency of a different filter without any visual cracks was
determined to be 99%. This demonstrates the value of the smoke dot test
to detect a filter problem before filter performance has deteriorated
significantly. However, even though defects in the DPM filter can
affect its efficiency, this may or may not affect a miner's personal
exposure to DPM. The smoke test can be done with a commercially
available ECOM AC gas analyzer or a Bacharach/Bosch smoke test
Apparatus. MSHA believes that this also is a good diagnostic tool for
DPM filters. Running this test on a routine basis would give
indications with any changes in the filter media. However, changes in
the color of the smoke dot may not indicate that miners would be
[[Page 48702]]
overexposed to DPM or that the filter should be removed from service.
This test may give an indication to the mine operator that a fault is
starting in the filter, and subsequently, that the DPM emissions could
be increasing.
MSHA asked for comments concerning what technical assistance the
Agency should provide to mine operators in retrofitting DPM control
devices and evaluating ventilation systems or filtration of cabs.
Commenters stated that MSHA should provide guidance in all these areas
that involve control technologies. MSHA has been and will continue to
provide these types of compliance assistance to underground metal and
nonmetal mine operators. Mine operators are encouraged to use the
Agency's DPM Single Source Page that includes comprehensive compliance
assistance tools addressing the aforementioned issues as well as
others.
MSHA has been instrumental in providing compliance assistance to
the mining industry. MSHA conducted a number of outreach workshops
throughout the country to discuss requirements of the DPM standard and
sampling and control technology information. These meetings were held
in Lexington, Kentucky; Kansas City, Missouri; Green River, Wyoming;
Albuquerque, New Mexico; Elko, Nevada; Coeur d'Alene, Idaho; Knoxville,
Tennessee; Des Moines, Iowa; and Ebensburg, Pennsylvania. MSHA also
completed baseline sampling at the underground mines covered by the DPM
standard, and made site-specific compliance assistance visits.
To further assist mine operators, MSHA and NIOSH have developed
compliance assistance tools, many of which are currently available to
operators on MSHA's DPM Single Source Page on MSHA's web site. The
NIOSH mining web page is available to mine operators as well. Mine
operators should give special attention to MSHA/NIOSH's Filter
Selection Guide. As explained earlier in this preamble, this document
provides mine operators with detailed step-by-step selection factors
that can be applied to particular pieces of diesel-powered equipment in
their mine. It is an interactive compliance assistance tool that allows
mine operators to answer questions on their individual mining operation
to select, retrofit and maintain the best available filter technology.
This guide will be updated as new technologies are introduced in the
underground mining industry.
Also included on MSHA's DPM sole source web page are the Estimator
computer program; a list of available filters and manufacturers; the
draft DPM compliance guide which contains MSHA's enforcement policy;
MSHA sampling procedures; the slide presentation from MSHA's outreach
seminars on the requirements of the DPM standard; information on how
MSHA calculated the error factor to be used when making compliance
determinations; a troubleshooting guide for addressing problems with
control technology; along with the NIOSH notes from the filter
workshops as discussed above. In addition, MSHA has posted ``Best
Practices'' for various issues concerning the use of DPM filters.
MSHA also provided compliance assistance at individual mines
through its involvement with bio-diesel projects, fuel catalyst
installations, and in-mine evaluations of DPM filter technologies.
MSHA's diesel testing laboratory located in Triadelphia, WV has been
active in evaluating many of these control technologies. The Agency
tested and provided information on the effects, if any, on nitrogen
dioxide production for specific catalyzed DPM filters.
The Agency continues to consult with the Metal and Nonmetal Diesel
Partnership (the Partnership). The Partnership is composed of NIOSH,
industry trade associations, and organized labor. MSHA is not a member
of the Partnership due to its ongoing DPM rulemaking activities.
A discussion of additional comments follows.
One commenter responded to MSHA's ANPRM questions regarding
retrofitting engines by stating that anything other than the original
engine model is unsuitable for a piece of diesel powered equipment.
According to this commenter, this would require prohibitive design
engineering analysis and implementation. MSHA agrees that on some
machines it may not be feasible to change engines. As engine
manufacturers develop cleaner engines, however, the older models are
being phased out and newer, cleaner engine models are available from
the same engine manufacturer. In some cases, the new engine models are
direct replacements for an older model. Among the benefits of
retrofitting a piece of diesel powered equipment with a cleaner engine
are better fuel economy, reduced DPM emissions, improved lubrication
systems, and better diagnostic tools, especially with the electronic
engines. A cleaner engine that emits less DPM will deposit less DPM on
the filter, thus resulting in longer intervals between regenerations,
especially in active regeneration systems or combination active/passive
regeneration systems.
MSHA asked for comments on whether cabs would be feasible and
appropriate for controlling DPM exposures. Commenters responded that
operators normally would not purchase a cab to control DPM. Cabs are
used for controlling exposures to respirable dust, however, and the
results of MSHA's sampling at the Greens Creek mine (MSHA, January
2003) show approximately 85% reduction in DPM when using a filtered cab
on a loader. Cabs, however, do not protect workers outside the cab or
downwind in series ventilation systems.
Another commenter stated that dimensional constraints of their mine
preclude use of cabs on equipment. MSHA is aware that some mines may
not be able to use cabs due to dimensional constraints. Environmental
cabs can be an effective feasible DPM control device for some mine
operators. Many new pieces of diesel powered equipment are sold with
enclosed cabs. Besides DPM exposure, an enclosed cab with filtered
breathing air would also help reduce exposure to other airborne
contaminants and noise.
Commenters provided information on the cost of filters, for both
passive and active systems. Information stated that active systems,
depending on product specifications, had a higher cost. MSHA agrees
with the commenters on cost. However, some of the higher costs of the
active system can be spread out over several vehicles. This means that
several filters that need active regeneration can be done at the same
regeneration station when filters are removed from the machine. The
mine can purchase backup filters for each machine and only one
regeneration station. If operators chose active, on-board,
regeneration, the unit that the machine plugs into can be available for
several machines. As stated previously, mine operators may need to
administratively adjust machine operating schedules to accommodate
active regeneration. MSHA believes that this filter technology is
economically feasible for the industry.
One commenter stated that there has been little experience with off
board regeneration. MSHA is aware of successful applications in M/NM
mines with active regeneration units. MSHA has posted on its homepage
best practices for active regeneration stations in M/NM mines. Several
problems that have been reported on active regeneration stations are
discussed below in association with regeneration stations located at
mines greater than 5000 feet in elevation.
[[Page 48703]]
The Agency requested data and information from the mining community
in its ANPRM on high altitude effects on control devices. Commenters
noted that MSHA had conducted the test in an underground coal mine
located in a high altitude area and that used diesel powered equipment.
MSHA worked with the coal mining industry to determine whether high
altitudes affected the performance of ceramic filters in controlling
DPM emissions. The Agency found no evidence to conclude that altitude
affects filtration performance. Some initial verbal comments were
received stating that active regeneration stations could not operate
effectively at higher altitudes, but further investigation by the coal
mine operators and the filter manufacturers indicated that the problem
was due to improper use of the equipment. One situation was that an
incorrect setting in the control panel on an active regeneration
station was determined to be the problem. In another instance, the mine
was not following the schedule for active regeneration and allowed the
filter to become overloaded with DPM thus preventing proper
regeneration. MSHA has made mine operators aware of these problems.
The Agency believes that at high altitudes, excessive DPM is
produced whenever the engine is improperly derated for elevation, such
as, the fuel:air ratio is not properly set. Mine operators should check
with the engine manufacturer or the engine distributor to verify that
the engine is set to the proper fuel setting specification, especially
when the engine is operating above 1000 feet in elevation. Increases in
DPM emitted could overload the filter and not allow proper regeneration
of either a passive or active system. Mine operators should install
backpressure monitoring devices when a filter is installed and follow
engine manufacturers' recommendations for maximum allowable exhaust
backpressure.
Some commenters to the ANPRM stated that diesel particulate filters
cannot work in their mines, or DPM filters are not feasible for a
number of reasons. MSHA has stated that all commercially available
ceramic filters can significantly reduce DPM levels. Regeneration
schemes have been identified in this preamble that can be feasibly
applied to all types of underground mining machines. Commenters also
stated that active regeneration systems are not feasible in their
mining operations although no specific scenarios were provided to the
Agency to respond to the concern. MSHA believes that the active systems
offer a variety of advantages, such as no dependence on exhaust gas
temperature or duty cycle, no increases in NO2, and easier
installation due to less restraints for installation of filters close
to the exhaust outlet. MSHA understands that active regeneration
systems may require mines to make adjustments in their fleet management
in order to guarantee that active regeneration works. However, active
regeneration systems are commercially available and feasible. MSHA
requests that mine operators provide more specific information on the
issues associated with the diesel powered equipment that would need
active regeneration systems.
Several commenters expressed the view that ventilation system
upgrades, though potentially effective in principle, would be
infeasible to implement for many mines. Specific problems that could
prevent mines from increasing ventilation system capacity include
inherent mine design and configurations (drift size and shape), space
limitations, and other external prohibitions, as well as economic
considerations. MSHA acknowledges that ventilation system upgrades may
not be a cost effective DPM control for mines with these limitations.
To the contrary, MSHA anticipates the metal and nonmetal underground
mining industry will comply with the DPM interim limit primarily
through the application of DPF systems rather than ventilation
upgrades.
At this time, MSHA estimates that mine operators may not be able to
achieve compliance with the proposed DPM limit for every underground
miner on every shift, particularly those engaged in inspection,
maintenance and repair activities. Existing Sec. 57.5060(d)(2)
identifies exceptional conditions where MSHA anticipates that it may
not be feasible for many mine operators to use engineering and
administrative controls. These conditions, which presently exist in
some mines include inspection, maintenance, and repair activities
conducted exclusively outside of environmentally controlled cabs or
enclosed booths. The existing rule requires mine operators to apply to
the Secretary for relief from applying control technology to reduce the
concentration limit. MSHA traditionally does not accept use of personal
protective equipment for compliance with its other exposure-based
standards applicable to metal and nonmetal mines, except while
establishing controls or during occasional entry into hazardous
atmospheres to perform maintenance or investigations. This proposal
would allow the use of personal protective equipment when all feasible
and administrative controls have been implemented. MSHA has included in
this proposed rule a tiered approach in controlling miners' exposures
that operators must use in achieving compliance. MSHA anticipates that
very few mine operators will have significant compliance problems with
meeting the proposed DMP limit in circumstances other than inspection,
maintenance, and repair activities.
The exposure data relied on by MSHA in making its technological
feasibility determinations include the final report on the 31-Mine
Study, and results of MSHA's DPM baseline compliance assistance
sampling conducted at each underground mine covered by the standard. In
the 31-Mine Study, the data showed that many miners' exposures are
below the proposed DPM limit without application of any additional
engineering or administrative controls. The sampling data includes
miners' exposures by job category to permit the Agency to pinpoint
those occupations in need of additional controls to achieve compliance
with the interim PEL.
DPM engineering controls are not new technology. Moreover, the
existing DPM standard was promulgated on January 19, 2001 (66 FR 5706)
with an effective date of July 19, 2002 for existing Sec. 57.5060(a).
As a result of the settlement agreement, MSHA allowed mine operators to
take an additional year in which to begin to install appropriate
controls to reduce DPM concentrations due to feasibility constraints.
Any controls currently used to meet the existing concentration limit
may also be used to reduce miners' exposures to DPM required under this
rulemaking.
Because of the lack of documented feasibility data for an interim
proposed PEL of less than 308 micrograms per cubic meter of air, MSHA
has concluded that there is insufficient information available to
support the feasibility of lowering the DPM limit at this time. The
Agency believes that this level is a reasonable interim limit for which
MSHA currently can document feasibility across the affected sector of
underground metal and nonmetal mines. MSHA is continuing to gather
information on the feasibility of compliance with a final DPM PEL of
less than 308 micrograms.
C. Economic Feasibility
MSHA believes the requirements for engineering and administrative
controls clearly meet the feasibility requirements of the Mine Act, its
legislative history, and related case law. A PEL of 308
[[Page 48704]]
micrograms per cubic meter of air is economically feasible for the
metal and nonmetal mining industry. Demonstrating economic feasibility
does not guarantee the continued viability of individual employers. It
would not be inconsistent with the Mine Act to have a company which
turned a profit by lagging behind the rest of an industry in providing
for the health and safety of its workers to consequently find itself
financially unable to comply with a new standard; Cf, United
Steelworkers, 647 F.2d at 1265. Although it was not Congress' intent to
protect workers by putting their employers out of business, the
increase in production costs or the decrease in profits would not be
sufficient to strike down a standard. Industrial Union Dep't., 499 F.2d
at 477. On the contrary, a standard would not be considered
economically feasible if an entire industry's competitive structure
were threatened. Id. at 478; see also, AISI-II, 939 F.2d at 980; United
Steelworkers, 647 F.2d at 1264-65; AISI-I, 577 F.2d at 835-36. This
would be of particular concern in the case of foreign competition, if
American companies were unable to compete with imports or substitute
products. The cost to government and the public, adequacy of supply,
questions of employment, and utilization of energy may all be
considered.
MSHA determined that an elemental carbon PEL comparable to the
existing concentration limit, along with primacy of engineering and
administrative controls as proposed would reduce the cost for
compliance required under the existing rule, and industry agrees.
Industry commenters stated that operator costs will be reduced since
MSHA would be changing the DPM surrogate from TC to EC which would
reduce the likelihood of contamination and eliminates the necessity to
re-sample. MSHA describes its finding in this preamble under section
VIII, ``Summary of Costs and Benefits,'' and in more detail in section
X, ``Regulatory Impact Analysis.'' A more comprehensive version is
available in the Preliminary Regulatory Economic Analysis on MSHA's web
site.
MSHA also believes that the proposed effective date of 30 days for
a final rule is feasible for underground mine operators in this sector
since the EC surrogate standard is comparable to the existing TC
surrogate standard which has been in effect since July 2002.
Additionally, as a result of a DPM partial settlement agreement mine
operators were given an additional year to begin to develop a written
strategy of how they intended to comply with the interim DPM
concentration limit. Operators with DPM levels above the concentration
limit were to begin to order and install controls to be in compliance
by July 20, 2003.
Nevertheless, MSHA recognizes that, in a few cases, individual mine
operators, particularly small operators, may have difficulty in
achieving full compliance with the interim limit immediately because of
a lack of financial resources to purchase and install engineering
controls. However, MSHA expects that these mine operators will be able
to achieve compliance with the recommended interim limit of 308
micrograms. Whether controls are feasible for individual mine operators
is based in part upon legal guidance from the Federal Mine Safety and
Health Review Commission (Commission). According to the Commission, a
control is feasible when it: (1) Reduces exposure; (2) is economically
achievable; and (3) is technologically achievable. Secretary of Labor
v. Callanan Industries, Inc., 5 FMSHRC 1900 (1983). In determining the
technological feasibility of an engineering control, the Commission in
Callanan has ruled that a control is deemed achievable if, through
reasonable application of existing products, devices, or work methods,
with human skills and abilities, a workable engineering control can be
applied. The control does not have to be an ``off-the-shelf'' item, but
it must have a realistic basis in present technical capabilities. Ibid.
at 1908.
In determining the economic feasibility of an engineering control,
the Commission has ruled that MSHA must assess whether the costs of the
control is disproportionate to the expected benefits, and whether the
costs are so great that it is irrational to require its use to achieve
those results. The Commission has expressly stated that cost-benefit
analysis is unnecessary in order to determine whether a noise control
is required. Ibid.
Consistent with Commission case law, MSHA considers three factors
in determining whether engineering controls are feasible at a
particular mine: (1) The nature and extent of the overexposure; (2) the
demonstrated effectiveness of available technology; and (3) whether the
committed resources are wholly out of proportion to the expected
results. A violation under the final standard would entail an Agency
determination that a miner has been overexposed, that controls are
feasible, and that the mine operator failed to install or maintain such
controls. According to the Commission, an engineering control may be
feasible even though it fails to reduce exposure to permissible levels
contained in the standard, as long as there is a significant reduction
in a miner's exposure. Todilto Exploration and Development Corporation
v. Secretary of Labor, 5 FMSHRC 1894, 1897 (1983). In Todilto, the
Commission ruled that engineering controls may also be feasible even
though they fail to reduce exposure to permissible levels contained in
the standard, as long as there is a significant reduction in exposure.
Current data establishes that DPF systems are extremely efficient
in that they reduce elemental carbon emissions from the tailpipe of a
piece of diesel powered equipment by as much as 99%. MSHA believes that
this is an exceptionally high efficiency rate for a single engineering
control in the mining industry. Therefore, MSHA intends to identify the
source or sources of DPM emissions leading to a miner's overexposure. A
mine operator would be required to install a single control or a
combination of controls that is capable of reducing the miners' DPM
exposure by 25%.
MSHA evaluated various engineering and administrative controls and
their related costs. Mine operators would have the flexibility under
the proposed rule to select the type of engineering and administrative
controls of their choice in order to reduce a miner's exposure to the
DPM limit. MSHA, however, believes that the most cost effective control
would be to install DPF systems due to their high rate of efficiency,
especially with respect to EC.
If MSHA finds that a miner is overexposed to the DPM standard, and
determines that engineering and administrative controls are feasible,
and that the operator failed to install or maintain such controls, MSHA
would issue a citation to the mine operator for overexposing the miner
to DPM. The citation would include an appropriate abatement date for
installing feasible controls. In the interim, a respiratory protection
program would be required while controls are being installed. As long
as miners' DPM exposures are reduced to or below the DPM limit, mine
operators have the flexibility under the proposed rule to choose the
engineering or administrative controls that best suit the mines'
circumstances. MSHA emphasizes that it is available to provide
compliance assistance to mine operators to help them select appropriate
control methods for reducing miners exposures based upon demonstrated
experience.
MSHA asked for comments concerning what type of technical
assistance the Agency should provide to mine operators in retrofitting
DPM
[[Page 48705]]
control devices, evaluating ventilation systems or filtration of cabs.
Commenters stated that MSHA should be providing guidance in all areas
that involve control technologies. MSHA agrees and will continue to
assist mine operators, however, MSHA expects mine operators to make
good faith efforts in attempting to achieve compliance, such as
beginning to order control technology to reduce DPM exposures.
VIII. Summary of Costs and Benefits
The provisions in this proposed rule will assist mine operators in
complying with the existing rule, thereby reducing a significant health
risk to underground miners. This risk includes lung cancer and death
from cardiovascular, cardiopulmonary, or respiratory causes, as well as
sensory irritation and respiratory symptoms. In Chapter III of the
Regulatory Economic Analysis in support of the January 19, 2001 final
rule (2001 REA), the Agency demonstrated that the rule will reduce a
significant health risk to underground miners. This risk included the
potential for illnesses and premature death, as well as the attendant
costs to the miners' families, to the miners' employers, and to society
at large. Benefits of the January 19, 2001 final rule include
reductions in lung cancers. MSHA estimated that in the long run, as the
mining population turns over, a minimum of 8.5 lung cancer deaths per
year will be avoided. MSHA noted that this estimate was a lower bound
figure that could significantly underestimate the magnitude of the
health benefits. For example the estimate based on the mean value of
all the studies examined in the January 19, 2001 rule was 49 lung
cancer deaths avoided per year.
The proposed rule results in net cost savings of approximately
$15,641 annually, primarily due to reduced recordkeeping requirements.
All MSHA cost estimates are presented in 2001 dollars. This represents
an average savings of $86 per mine for the 182 underground metal/non-
metal mines that would be affected by this proposed rule. Of these 182
mines, 65 have fewer than 20 workers, 113 have 20 to 500 workers; and 4
have more than 500 workers. The cost savings per mine for mines in
these three size classes would be $102, $77, and $77, respectively. In
the 2001 REA, the Agency estimated that the costs per underground
dieselized metal or nonmetal mine to be about $128,000 annually, and
the total cost to the mining sector to be about $25.1 million a year,
even with the extended phase-in time. Nearly all of those anticipated
costs would be investments in equipment to meet the interim and final
concentration limits.
IX. Section-by-Section Discussion of the Proposed Rule
A. Section 57.5060(a)
Existing Sec. 57.5060(a) establishes an interim DPM concentration
limit of 400 micrograms of TC per cubic meter of air (400TC
[mu]g/m\3\). In the settlement agreement, MSHA agreed to propose to
change the surrogate from TC to EC, and to propose to establish an
interim limit based on a miner's personal exposure rather than an
environmental concentration. Accordingly, the proposed rule would
establish an interim permissible exposure limit (PEL) of 308 micrograms
of EC per cubic meter of air (308TC [mu]g/m\3\). This
proposed EC-based limit represents the existing TC limit divided by a
conversion factor of 1.3, as established in the settlement agreement.
MSHA believes that the proposed limit is equivalent to the existing
interim concentration limit of 400TC [mu]g/m\3\.
MSHA's position at this time is that a limit of 308 [mu]g/m\3\,
based on EC, is both technologically and economically feasible for the
metal and nonmetal mining indutry to achieve. Although the risk
assessment indicates that a lower interim DMP limit would enhance miner
protection, it would be infeasible for the underground metal and
nonmetal mining industry to reach a lower interim limit.
MSHA is not reducing the protection for miners afforded by the
existing interim TC concentration limit. MSHA intends to finalize an
interim EC limit that provides at least the same degree of protection
to miners as the existing interim limit. MSHA believes that
establishing a standard that focuses control efforts on diminishing the
DPM level in air breathed by the miner is at least as protective as the
interim concentration limit.
The basis for this position is found in the 31-Mine Study, which
concluded that the submicron impactor was effective in removing the
mineral dust, and therefore its potential interference, from the DPM
sample. Remaining carbonate interference is removed by subtracting the
4th organic peak from the analysis. No reasonable method of sampling
was found that would eliminate interferences from oil mist or that
would effectively measure DPM levels in the presence of environmental
tobacco smoke (ETS) with TC as the surrogate.
Using EC as the surrogate would enable MSHA to directly sample
miners, such as those who smoke or load ANFO, for whom valid personal
sampling would be difficult when TC is the surrogate.
Because EC comprises only a fraction of the TC, a conversion factor
must be used to convert the interim concentration limit to an EC
exposure limit. To convert the interim TC concentration limit in Sec.
57.5060(a) to an equivalent EC exposure limit, MSHA is proposing to use
a factor of 1.3, to be divided into 400TC [mu]g/
m3. Thus, the measured value of EC times 1.3 produces a
reasonable estimate of TC. This 1.3 factor was specified under the
terms of the settlement agreement to convert an EC measurement into an
estimate of TC without interferences and is based on the median total
carbon to elemental carbon (TC/EC) ratio observed for valid samples in
the 31-Mine Study. The 1.3 factor is also consistent with information
supplied by NIOSH indicating that the ratio of TC to EC in the 31-Mine
Study is 1.25 to 1.67. Most commenters to MSHA's ANPRM supported an
interim EC PEL of 400TC [mu]g/m3 / 1.3 =
308EC [mu]g/m3.
Commenters representing the metal and nonmetal mining industry and
labor strongly supported a change in the surrogate from TC to EC. These
commenters stated that, given the interferences known to be present in
underground mining environments, using EC as the surrogate would
improve the validity of samples. They also pointed out that this change
is consistent with the settlement agreement. Other commenters opposed
changing the surrogate. Some of these commenters stated that since DPM
has many components, and there is no formula for the exact amount of EC
in diesel exhaust, TC is a more accurate measure of DPM than is EC,
presumably because it includes more of the DPM.
Some commenters also stated that there is no evidence in the
rulemaking record to support this change. According to these
commenters, NIOSH must provide a clear statement that EC is an accurate
surrogate over the full range of mining conditions and must also
provide a formula for converting EC to DPM that meets the NIOSH
accuracy criterion. In response, the existing DPM rulemaking record
contains NIOSH's position on an appropriate surrogate, and NIOSH
recommended that EC rather than TC should be used as the surrogate for
DPM. MSHA agrees.
MSHA has found that EC more consistently represents DPM. In
comparison to using TC as the DPM surrogate, using EC would impose
fewer restrictions or caveats on sampling strategy (locations and
durations), would produce a measurement much
[[Page 48706]]
less subject to questions, and inherently would be more precise.
Furthermore, NIOSH, the scientific literature, and the MSHA laboratory
tests indicate that DPM, on average, is approximately 60 to 80%
elemental carbon, firmly establishing EC as a valid surrogate for DPM.
Some commenters opposing a change in the surrogate stressed that
the mix of EC + OC (to equal TC) is highly variable. Some commenters
questioned the use of EC as a surrogate for DPM because the EC:TC ratio
varies with each engine and EC is emitted from other sources. Other
commenters, noting that a specific mine in the 31-Mine Study had an
EC:TC ratio of 85%, stated that there is no perfect way to monitor DPM
using surrogates.
MSHA agrees that the EC:TC ratio can vary significantly, not only
from mine to mine but also within a mine, depending on equipment
configuration and usage. MSHA also agrees that there is no perfect way
to precisely quantify DPM. Using EC as a surrogate, however, results in
a much more accurate assessment of miners' exposures to DPM than using
TC. MSHA seeks information and data on the appropriateness of 1.3 as
the factor to convert EC to TC, and an interim EC limit of 308
micrograms.
As part of the settlement agreement, MSHA agreed that the Agency
will issue citations for violations of the interim exposure limit only
after MSHA and NIOSH are satisfied with the performance characteristics
of the SKC sampler and the availability of practical mine worthy filter
technology, and MSHA has had the opportunity to train inspectors,
conduct baseline sampling and provide compliance assistance at
underground metal and nonmetal mines using diesel-powered equipment.
MSHA will continue consulting with NIOSH, industry and labor
representatives on the performance of the SKC sampler and the
availability of practical mine-worthy filter technology.
MSHA trained the Metal and Nonmetal district health specialists and
industrial hygienists on diesel particulate sampling in Beckley, West
Virginia in September 2002. These individuals returned to their
respective districts and trained MSHA compliance specialists on diesel
particulate sampling. MSHA has completed the commpliance assistance
baseline sampling. As part of its compliance assistance efforts, MSHA
personnel were available during the baseline sampling to provide
guidance to mine operators on sampling procedures.
Additionally, MSHA trained members of the mining industry on
conducting DPM sampling and made that training available to industry
personnel at compliance assistance workshops following the Outreach
Seminars on Diesel Particulate Rules for Underground Metal and Nonmetal
Mines. These seminars and workshops were conducted at nine cities
during September and October 2002.
MSHA and NIOSH have reviewed the performance characteristics of the
SKC sampler and are satisfied that it accurately measures exposures to
DPM. Results of the 31-Mine Study demonstrated that the SKC submicron
impactor removed potential interferences from mineral dust from the
collected sample. MSHA concluded in its findings in the study, however,
that:
No reasonable method of sampling was found that could eliminate
interferences from oil mist or that would effectively measure DPM
levels in the presence of ETS with TC as the surrogate.
Furthermore, MSHA has found that use of elemental carbon eliminates
potential sample interference from drill oil mist, tobacco smoke, and
organic solvents.
Some industry commenters stated that the sampling and analytical
processes are too new for regulatory use. According to these
commenters, SKC recently changed the impactor, and NIOSH should test
the new SKC sampler and evaluate its comparability to the model used in
the 31-Mine Study. One of these commenters stated that the shelf life
of the prior sampler affected TC measurements by adsorbing OC from the
polystyrene assembly onto the filter media and increasing TC
measurement. Some commenters also stated that there are significant
back-order and manufacturing delays for samplers and that operators who
sample alongside MSHA need ample notice to have enough samplers
available.
MSHA purchased many of the initial production runs of these
samplers to conduct its compliance assistance baseline sampling. Once
the initial orders were filled, the sampler became more widely
available.
Prior to the 31-Mine Study, MSHA had determined the deposit area of
the sample filter to be 9.12 square centimeters with a standard
deviation of 3.1 percent. During the initial phases of the 31-Mine
Study, it became apparent that the variability of the deposit area was
greater than originally determined. The filter area is critical to the
concentration calculation. The filter area (square centimeters) is
multiplied times the results of the analysis (micrograms per square
centimeter) to get the total filter loading (micrograms). While
individual filter areas could be measured, it is more practical to have
a uniform deposit area for the calculations. As a result, NIOSH and
MSHA consulted with SKC to develop an improved filter cassette design.
SKC, in cooperation with MSHA and NIOSH, then modified the DPM cassette
following the 31-Mine Study.
The modification was limited to replacing the foil filter capsule
with a 32-mm ring. This was done to give a more uniform deposit area
(8.04 square centimeters) and to accommodate two 38-mm quartz fiber
filters in tandem (double filters). These double filters are assembled
into a single cassette along with the impactor. The 32-mm ring gives a
filter deposit area of 8.04 square centimeters, with negligible
variability. The 38-mm filters also eliminate cassette leakage around
the filters. These modifications were completed and incorporated into
units manufactured after November 1, 2002. Because the design of the
inlet cyclone, impaction nozzles, the impaction plate and the flow rate
did not change, the modifications to the filter assembly did not alter
the collection or separation performance of the impactor. Throughout
the compliance baseline sampling, the impactor has been a consistent
and reliable sampling cassette.
Tandem filters were used in the oil mist and ANFO interference
evaluations. The top filter collects the sample and the bottom filter
is a ``dynamic blank.'' The dynamic blank provides a unique field blank
for each DPM cassette. The proposed use of elemental carbon as a
surrogate would resolve the commenter's concern about shelf life and OC
out-gassing on the filter. Shelf life and OC out-gassing are issues
relative to organic carbon measurements. These two issues do not apply
to an elemental carbon measurement. Once the cassettes have been
preheated, during manufacturing, there is no source, other than
sampling, to add elemental carbon to the sealed cassette filters.
In the ANPRM, MSHA asked questions on three topics relating to DPM
sampling and analysis:
(1) Interferences
In response to the question on interferences when EC is used as the
surrogate, some commenters stated that interferences were thoroughly
discussed in the final rule preamble and that reasonable practices to
avoid them were stipulated in the rule itself. According to these
commenters, this problem should not be revisited in this rulemaking.
[[Page 48707]]
Other commenters maintained that the 31-Mine Study did not contain
the necessary protocols to address all potential interferences. Thus,
in their view, MSHA does not have all the data required to answer this
question. More specifically, some commenters stated that carbonaceous
particulate in host rock has a smaller diameter than the impactor cut
point and so may contaminate EC samples. No data were presented to
support this claim. These commenters concluded that MSHA should propose
additional research and seek comments on the research before concluding
that sampling EC with an impactor will eliminate all interference
problems. On the other hand, NIOSH, in its response to the ANPRM,
stated that the only non-diesel source of EC that is known to be
present in a metal/non-metal mine is graphitic mineral ore dust. NIOSH
further stated that collection of this dust on the sample filter is
prevented by the impaction plate in the SKC DPM cassette.
(2) Field Blanks
A field blank is an unexposed control filter meant to account for
background interferences and systematic contamination in the field,
spurious effects due to manufacturing and storage of the filter, and
systematic analytical errors. The tandem filter arrangement in the
sample cassette provides a primary filter for collecting an air sample
and a second filter, behind (after) the primary, that provides a
separate control filter for each sample. This is especially convenient
for industry sampling, since it eliminates the need to send a separate
control filter to the analytical lab. MSHA requests comments as to
industry experience with this sampling equipment.
In its comments on the ANPRM, NIOSH noted that two types of blanks,
media and field, are normally used for quality assurance purposes. A
media blank accounts for systematic contamination that may occur during
manufacturing or storage. A field blank accounts for possible
systematic contamination in the field. NIOSH does not recommend use of
field blanks when EC is the surrogate. This is because EC measurements
are not subject to sources of contamination in the field that would
affect OC and TC results. Quartz-fiber filters are prone to OC vapor
contamination in the field and to contamination by less volatile OC
(e.g., oils) during handling. However, such contamination is irrelevant
when EC is the surrogate.
Several commenters supported the use of field blanks, even if EC is
the surrogate. These commenters pointed out that using field blanks is
standard IH practice and stated that manufacturing problems with SKC
impactor provide further justification. One commenter asked that we use
one blank from the same and one from a different manufacturer lot.
MSHA agrees both media and field blanks are desirable, even when
elemental carbon is used as the surrogate. The use of such blanks is
standard laboratory procedure and adds credibility to sample results.
Field blanks adjust for systematic laboratory errors and for systematic
contamination of samples from unforeseen or uncontrollable sources.
Accordingly, MSHA will adjust the EC result obtained for each sample by
the result obtained for the corresponding media blank when a compliance
concentration is measured and by the field blank (tandem filter) result
when a noncompliance determination is made.
(3) Error Factor
MSHA intends to cite a violation of the DPMEC exposure
limit only when there is validated evidence that a violation actually
occurred. As with all other measurement-based metal/nonmetal compliance
determinations, MSHA would issue a citation only if a measurement
demonstrated noncompliance with at least 95-percent confidence. We
would achieve this 95-percent confidence level by comparing each EC
measurement to the EC exposure limit multiplied by an appropriate
``error factor.''
Most commenters concurred with MSHA's intention to apply such an
error factor, though they differed as to how this error factor should
be established. Some other commenters, however, recommended citing at a
substantially lower confidence level, using the limit of detection of
the sampling instrument as replacement for the error factor. These
commenters gave two reasons in support of this recommendation: (1) In
issuing a citation for noncompliance, the standard of proof should,
according to this commenter, be preponderance of evidence rather than
beyond a reasonable doubt. The preponderance of evidence indicates a
violation whenever a measurement exceeds the exposure limit plus the
limit of detection. (2) Conventional public health reasoning and legal
precedents call for caution on the side of protecting health, rather
than preventing unwarranted citations. In addition, commenters stated
that if a measurement failed to demonstrate compliance at a 95-percent
confidence level, then this should trigger some action such as
additional sampling, i.e., the EC measurement should be divided, rather
than multiplied, by MSHA's proposed error factor to provide an ``action
level.''
Contrary to these commenters' suggestions, the historical and
prevailing practice, in both OSHA and MSHA, traditionally has been to
cite noncompliance only when noncompliance is indicated at a high level
of confidence. Although, the citation threshold value suggested by
these commenters accounts for some analytical imprecision, as
quantified by the limit of detection, it fails to account for other
sources of measurement uncertainty, such as random variability of
airflow through the filter.
Another commenter questioned the use of any constant error factor,
because of changes in the EC:OC ratio under varying maintenance and
operating conditions. Although MSHA regards such variability as
relevant to the issue of choosing an appropriate surrogate, it is not
relevant to determining an appropriate error factor if EC is selected
as the surrogate. EC is the quantity to be measured under the proposal,
and variability in the EC:OC ratio has no known impact on the accuracy
of an EC concentration measurement made using the SKC sampler and the
NIOSH 5040 analytical method.
Among those commenters supporting MSHA's use of an error factor
providing 95-percent confidence in each citation, some advocated
continued use of the factor specified in the settlement agreement:
12.2% for an interim EC limit of 308 [mu]g/m3. This value
was based on the paired punch data obtained from the 31-Mine Study,
combined with independent estimates of variability in airflow and the
deposit area on the sample filter. Other commenters, noting changes in
the design of the SKC sampler since the 31-Mine Study, stated that
sampler accuracy should be re-evaluated based on the redesigned sampler
and that establishment of the error factor should be made a part of the
rulemaking process.
MSHA disagrees that the establishment of an error factor for an
airborne contaminant should be part of the rulemaking process. MSHA is
not proposing an error factor in this rulemaking, but rather,
discussing the procedure used to obtain the error factor. This
procedure is further discussed on the MSHA web site--Single Source Page
for Metal and Nonmetal Diesel Particulate Matter Regulations. Error
factors are based on sampling and analytic errors. The manufacturers of
sampling devices thoroughly investigate and quantify the error factors
for their devices. While
[[Page 48708]]
MSHA does not frequently change an error factor, it retains that
latitude should significant changes to either analytical or sampling
technology occur.
The formula for the error factor was based on three factors
included in the DPM settlement agreement and involved in an eight-hour
equivalent full-shift measurement of EC concentration using Method
5040: (1) Variability in air volume (i.e., pump performance relative to
the nominal airflow of 1.7 L/min), (2) variability of the deposit area
of particles on the filter (cm2), and (3) accuracy of the
laboratory analysis of EC density within the deposit ([mu]g/
cm2). Modifications made to the sampler since the time of
the 31-Mine Study have no bearing on the first and third of these
factors. For the error factor specified in the settlement agreement,
variability of the filter deposit area was represented by a 3.1 percent
coefficient of variation, based on an experiment carried out before the
foil filter capsule in the sampling cassette was replaced by a 32-mm
ring. Measurements subsequent to introduction of the ring show that
variability of the filter deposit area is now less than 3.1 percent
(Noll, J. D., et al., ``Sampling Results of the Improved SKC Diesel
Particulate Matter Cassette''). This change slightly reduces the error
factor stipulated for EC measurements in the settlement agreement, but
not by enough to be of any practical significance.
Another commenter, stressing the interdependence of inter- and
intra-laboratory analytical variability, stated:
MSHA should create an error factor model that accounts for the
joint and related variability in laboratory analysis, and then
combine that variability with pump flow rate, sample collection
size, other sampling and analytic variables * * * [t]hen, based upon
a statistically strong database, determine the appropriate error
factor for elemental carbon samples.
MSHA agrees and this was done for the error factor stipulated in
the settlement agreement.
This commenter also suggested that the error factor should include
a ``component accounting for location on the filter from which the
sample punch was collected.'' The analytical method (NIOSH 5040) relies
on a punch taken from inside the deposit area on the sample filter. In
effect, the punch is a sample of the dust sample. Presumably, the
purpose of the suggested error factor component would be to account for
uniformity in the distribution of DPM deposited on the filter, as
reflected by different possible locations at which a punch might be
extracted. MSHA agrees that uniformity of the DPM deposit should be
included in the error factor. The method MSHA used to evaluate the
accuracy of the analytical method involved comparing two punches taken
from different locations on the same filter. Therefore, variability
between punch results due to their location on the filter is already
included in the error factor as calculated by MSHA.
The commenter further recommended that MSHA implement sample review
and chain of custody procedures, that MSHA retain a portion of each
sample for further analysis by the operator, and that the Agency
institute inter- and intra-lab analysis of spiked EC samples, along the
lines of an AIHA PAT (American Industrial Hygiene Association
Proficiency Analytical Testing) program, in order ``to obtain reliable,
reproducible information.''
The MSHA Analytical Laboratory is AIHA (ISO 17025) accredited. As
such, the Laboratory is required to develop and follow specified
measurement assurance procedures. These procedures include calibration,
assessing limits of detection, and determining sampling and analytical
errors. These are done by standard laboratory methods, which are
outside the scope of this rulemaking. MSHA would encourage the
laboratories that would perform NIOSH 5040 analysis to develop and
institute a PAT-like round-robin program. However, establishing such a
program is not only outside the scope of this rulemaking but also
outside MSHA's mandate.
MSHA will be extracting and analyzing a second punch from any
sample filter that indicates an overexposure (the two punch results
will be averaged for purposes of determining noncompliance). As a
result, sufficient sample will not be available to send to other
laboratories for analysis. The inter-laboratory paired punch
comparison, conducted on data from the 31-Mine Study, provided a
rigorous evaluation of intra- and inter-laboratory variability in EC
analysis. Based on 642 matched pairs of punches analyzed at four
laboratories, the coefficient of variation in analytical EC measurement
error, reflecting the combination of intra- and inter-laboratory
imprecision, was estimated to be 6.5 percent at filter loadings
corresponding to an EC concentration at or above the proposed interim
limit of 308EC [mu]g/m3. This is considered an
excellent degree of agreement for an inter-laboratory comparison.
Sample collection procedures and chain of custody, along with other
sampling issues, are addressed in the MSHA Metal and Nonmetal Health
Inspection Procedures Handbook. Operators are aware that MSHA inspects
without prior notice. Therefore, operators who wish to collect side-by-
side samples should have filter cassettes and other sampling equipment
and supplies available.
Final Concentration Limit
B. Section 57.5060(c)
Existing Sec. 57.5060(c) addresses application and approval
requirements for an extension of time for mine operators to reduce the
concentration of DPM to the final TC concentration limit of 160
micrograms per cubic meter of air. Mine operators seeking an extension
must apply to the Secretary. Only consider technological constraints
can be considered as a basis for approving an extension. The current
rule allows only one special extension per mine, and this extension is
limited to two years. Operators must certify that one copy of the
application was posted at the mine site for at least 30 days prior to
the date of application. Operators also must give the authorized
representative of miners a copy of the plan. The current rule does not
apply to the interim concentration limit.
In the settlement agreement, MSHA agreed to propose to adapt this
provision to the interim limit, include consideration of economic
feasibility, and allow for annual renewals of special extensions.
Proposed Sec. 57.5060(c) would apply to both the interim and the final
DPM limits. The proposed section would add consideration of economic
feasibility in weighing whether operators qualify for an extension.
Economic constraints as well as technological constraints may limit a
mine operator's ability to come into compliance with either the interim
or the final DPM concentration limit. An example of such an economic
limitation is the case where the cost of modification to a piece of
diesel-powered equipment that would be required to bring the equipment
operator's exposure into compliance with the PEL would exceed the value
of the equipment. In such an instance, additional time may be required
to purchase and implement other effective controls, such as newer
equipment with engines that emit less DPM or changes in the ventilation
system of the mine.
The proposed section would remove the limit on the number of
extensions that may be granted to each mine, but would limit each each
extension to one year. The MSHA district manager, rather than the
Secretary, could grant extensions. The application for an extension
would include information that demonstrates how the economic or
technological feasibility issues affect the mine operator's ability to
comply with
[[Page 48709]]
the standard. The application would also include the most recent DPM
monitoring results.
Section 57.5060(c)(vi) would require the mine operator to specify
the actions that the operator intends to take during the extension
period to minimize miner's exposures to DPM. These actions may include
maintaining existing controls, conducting periodic monitoring of
miner's exposures, and providing appropriate respiratory protection and
requiring miners to use such respirators. MSHA does not intend that
personal protective equipment be permitted during the extension as a
substitute for engineering and administrative controls that can be
implemented immediately. In these circumstances, MSHA would consider
such controls to be feasible and would require mine operators to
implement them prior to granting an extension.
Finally, the proposed rule would retain the requirement that
operators certify to MSHA that one copy of the application was posted
at the mine site for at least 30 days prior to the date of application,
and another copy was provided to the authorized representative of
miners. This record would continue to be subject to records
requirements under Sec. 57.5075 of the existing standard.
Existing Sec. 57.5060 requires the mine operator to comply with
the terms of any approved application for a special extension, and post
a copy of the approved application for a special extension at the mine
site for the duration of the special extension period. MSHA's proposed
rule also would require operators to provide a copy of the approved
application to the authorized representative of miners.
The ANPRM solicited comments on circumstances that would
necessitate an extension of time to come into compliance with the PEL
and the final concentration limit. Some commenters stated that there
were no circumstances that would necessitate an extension of time.
Various commenters stated that there should be no extensions. Some
commenters also said that the Mine Act does not require a feasibility
determination for each mine. Others stated that the technology is
available and referenced in the 1998 Verminderung der Emissionen von
Realmaschinen en Tunnelbau (VERT) study.
Some commenters favored granting extensions based on operators'
good faith efforts to reduce DPM. One commenter said that the 31-Mine
Study showed that many mines would be unable to comply with either the
interim or final limit. Some commenters said that extensions would be
necessary when technological or economic feasibility precludes
compliance and that granting extensions should be site-specific.
MSHA also solicited comments on the duration of the extension. Some
commenters wanted one-year, renewable extensions. A few commenters
stated that extensions should be granted automatically until control
technology is feasible, while others felt that extensions should be
granted liberally and renewed as long as the mine is making good faith
efforts. Several commenters also stated that in-mine applications of
control technology can differ from lab results and that manufacturers
are developing new technology for EPA compliance, thus research and
development for control technology on existing engines is not cost
effective.
MSHA asked for comments on what actions mine operators must take to
minimize DPM exposures if they are operating under an extension. Some
commenters stated that a detailed compliance plan specifying how the
limit would be met should be required. These same commenters said that
a public hearing on granting an extension should be held at the
operator's or union's request. Use of administrative controls and PPE
were recommended by several commenters. Commenters also said that
research on respiratory protective devices such as PAPRs (powered air
purifying respirators) is needed.
MSHA agrees that applications for extension should include the
actions a mine operator will take during the extension to reduce the
miner's exposure level to the interim PEL or the final concentration
limit such as monitoring, ordering controls, adjusting ventilation,
respiratory protection, and other good faith actions of the mine
operator. The circumstances under which MSHA would propose to require
respiratory protection are in new Sec. 57.5060(d).
MSHA is proposing to revise Sec. 57.5060(c) as agreed to in the
DPM settlement agreement. MSHA has further reviewed and analyzed the
effect of this standard and is concerned that it would duplicate the
regulatory objectives addressed under new Sec. 57.5060(d) and the
intended hierarchy of controls for the DPM rule. In the preamble to the
existing rule at page 5861, MSHA stated:
Extension application. Sec. 57.5060(c)(1) provides that if an
operator of an underground metal or nonmetal mine can demonstrate
that there is no combination of controls that can, due to
technological constraints, be implemented within five years to
reduce the concentration of DPM to the limit, MSHA may approve an
application for an extension of time to comply.
The Agency intended for the existing provision to address
circumstances where mine operators would need additional time to
implement a technological solution to controlling DPM in their
individual mines. When MSHA promulgated the DPM rule, it intended for
this provision to give flexibility to a regulatory scheme that
prohibited use of administrative controls and respiratory protection.
MSHA requests comments on whether the proposed provision for the
extension of time to comply with the interim PEL and the final
concentration limit would be necessary, and examples of how this
requirement would benefit mine operators if included in the final
regulatory framework. MSHA is interested in avoiding duplication and
requiring additional paperwork from the mining industry in order to
resolve feasibility issues at individual mining operations. The Agency
needs further input from the public on the effectiveness of proposed
Sec. 57.5070(c) and how this provision fits within the comprehensive
structure of this rulemaking.
C. Section 57.5060(d)
Existing Sec. 57.5060(d) permits miners engaged in specific
activities involving inspection, maintenance, or repair activities, to
work in concentrations of DPM that exceed the interim and final limits,
with advance approval from the Secretary. MSHA specifies in the
standard that advance approval is limited to activities conducted as
follows:
(i) For inspection, maintenance or repair activities to be
conducted:
(A) In areas where miners work or travel infrequently or for
brief periods of time;
(B) In areas where miners otherwise work exclusively inside of
enclosed and environmentally controlled cabs, booths and similar
structures with filtered breathing air; or
(C) In shafts, inclines, slopes, adits, tunnels and similar
workings that the operator designates as return or exhaust air
courses and that miners use for access into the mine or egress from
the mine;
Operators must meet the conditions set forth in the standard for
protecting miners when they engage in the specified activities in order
to qualify for approval of the Secretary to use respiratory protection
and work practices. MSHA considers work practices a component of
administrative controls.
In tandem with this requirement is existing Sec. 57.5060(e) which
prohibits
[[Page 48710]]
use of respiratory protection to comply with the concentration limits,
except as specified in an approved extension under Sec. 57.5060(c) and
as specified in approved conditions related to inspection, repair, or
maintenance activities. Section 57.5060(f) prohibits use of
administrative controls to comply with the concentration limits.
MSHA agreed under the DPM settlement agreement to propose a
revision of the existing Sec. 57.5060(d) and implement the current
hierarchy of controls as adopted in the Agency's other exposure-based
health standards for metal and nonmetal mines, and consider requiring
application to the Secretary before respirators could be used to comply
with the DPM standard. The settlement agreement further specifies that
employee rotation would not be allowed as an administrative control for
compliance with this standard.
When a miner's exposure exceeds the PEL or the concentration limit,
proposed Sec. 57.5060(d) would require that operators reduce the
miner's exposure by installing, using and maintaining feasible
engineering and administrative controls; except operators would then be
prohibited from rotating a miner to meet the DPM limits. Under its
current policy, MSHA allows mine operators to abate a citation for an
overexposure to airborne contaminants (air quality) by using feasible
engineering or administrative controls to reduce the miner's exposure
to the contaminant's enforcement level (See MSHA Program Policy Manual,
Volume IV, Parts 56 and 57, Subpart D, Section .5001(a)/.5005, 08/30/
1990). When controls do not reduce a miner's exposure to the DPM
limits, controls are infeasible, or controls do not produce significant
reductions in DPM exposures, operators would have to continue to use
all feasible controls and supplement them with a respiratory protection
program, the details of which are discussed below in this preamble.
Therefore, MSHA is proposing to remove current Sec. 57.5060(e)
prohibiting respiratory protection as a method of compliance in the DPM
rule, and Sec. 57.5060(f) which prohibits the use of administrative
controls for compliance. Administrative controls, however, were
uniquely defined in the existing rule as ``worker rotation.'' MSHA has
historically considered other types of controls, besides worker
rotation, to be administrative controls.
Administrative controls, such as work practice controls, were
permitted. In the context of the existing rule, engineering controls
were intended to refer to controls that remove the DPM hazard by
applying such methods as substitution, isolation, enclosure, and
ventilation.
Work practice controls were referred to as specified changes in the
manner work tasks are performed in order to reduce or eliminate a
hazard. The Agency strongly believes that these types of administrative
controls do not compromise miners' health and safety and would not
reduce the level of their protection as provided under the existing
final rule. Moreover, mine operators should be given the flexibility to
use them to control miners' exposures under a revised DPM rule.
Commenters should submit information and supporting data on appropriate
administrative controls for a final rule.
At the present time, operators are not required to develop written
administrative control procedures, nor a written respiratory protection
program when using these control methods to reduce miners' exposures to
airborne contaminants in MSHA's air quality standards at 30 CFR
57.5001/57.5005.
In the ANPRM, MSHA asked commenters for information and data on the
appropriate role for administrative controls and respirators in
underground metal and nonmetal mines in a proposed rule. Most
commenters supported removing the prohibition in order to have greater
compliance flexibility.
MSHA asked the mining community whether it should require written
administrative control procedures when operators are required to use
controls to reduce miners' exposures. Commenters were divided on this
issue.
MSHA received some objections from the public as to written
administrative control strategies. The commenters stated that such a
requirement would increase compliance costs and reduce efficiency and
personnel availability. Other commenters recommended that MSHA require
operators to have written administrative control strategies and post
them on the mine's bulletin board. Commenters should submit to MSHA any
information on the benefits and cost implications of including in a
final rule a requirement to develop written administrative control
procedures and post the procedures on the mine's bulletin board.
The proposed changes to Sec. 57.5060(d) described above might
appear to alter the way mine operators will be required to control DPM
exposures compared to the requirements contained in the existing rule.
However, in most cases, the proposed changes and the existing rule
impose similar requirements. The mining community will find that these
proposed changes are largely intended to simplify understanding of the
rule's requirements for controlling DPM exposures and to reduce
unnecessary paperwork.
MSHA would consider an engineering or administrative control to be
effective in reducing DPM exposure if credible scientific or
engineering studies or analysis using similar diesel equipment operated
under similar conditions have demonstrated the capability, either by
itself or in combination with other controls, to achieve significant
DPM exposure reductions, in either laboratory or field trials. MSHA
believes that a 25% or greater reduction in DPM exposure should be
considered significant. MSHA, however, requests further comments on
what would constitute a significant reduction in a miner's DPM
exposure.
MSHA considers an engineering control to be technologically
achievable if through reasonable application of existing products,
devices, or work methods, with human skills and abilities, a workable
engineering control can be applied. The control does not have to be
``off the shelf,'' but it must have a realistic basis in present
technical capabilities.
As discussed elsewhere in this preamble (Feasibility), MSHA would
consider, for example, a ceramic DPM filter to be a technologically
feasible control for a piece of diesel equipment if there was evidence
that the filter had been successfully applied to a similar engine
subjected to similar operating conditions. The fact that a ceramic DPM
filter had not been previously applied to that particular make and
model of engine, or to that particular make and model of mining
equipment would not, by itself, constitute a basis for determining that
the application would be technologically infeasible.
Also, the fact that the duty cycle of a particular piece of mining
equipment might not be sufficient for passive controlled regeneration
of a ceramic DPM filter would not, by itself, constitute a basis for
determining that the application of that filter to that piece of mining
equipment is technologically infeasible.
In this example, unless additional substantive information
establishing the technological infeasibility of the application is
presented, MSHA would consider the filter to be a technologically
feasible engineering control. Furthermore, MSHA would consider the
filter to be technologically feasible even though a certain amount of
applications engineering might be required to produce a workable or
optimal system, including the need to re-locate, re-route or otherwise
modify exhaust system components to facilitate
[[Page 48711]]
filter installation, and the possible need for either on-board or off-
board active or active/passive filter regeneration.
MSHA would also consider certain traditional methods for control of
exposure to airborne contaminants to be technologically feasible for
controlling exposures to DPM, such as improved ventilation (main and/or
auxiliary) and enclosed cabs with filtered breathing air. Improving
ventilation may involve upgrading main fans, use of booster fans, and
use of auxiliary fans that may or may not be connected to flexible or
rigid ventilation duct, as well as installation of ventilation control
structures such as air walls, stoppings, brattices, doors, and
regulators. At most mines, cabs with filtered breathing air are
technologically feasible for many newer model trucks, loaders, scalers,
drills, and other similar equipment. However, use of enclosed cabs with
filtered breathing air may not be feasible as a retrofit to certain
older equipment or where the function performed by miners using a
particular piece of equipment is inconsistent with any type of cab
(e.g., loading blastholes from a powder truck, installing utilities
from a scissors-lift truck) or where the height of the mine roof is not
sufficient for cab clearance. Other examples of engineering controls
that MSHA would consider to be technologically feasible include certain
alternative fuels, fuel blends, fuel additives, and fuel pre-treatment
devices, and replacement of older, high-emission engines with modern,
low-emission engines.
In determining economic feasibility, MSHA would consider whether
the costs of implementing the control are disproportionate to the
expected DPM concentration or exposure reduction, and whether the costs
are so great that it would be unreasonable to require its use to
achieve those results. MSHA would, for example, expect ceramic DPM
filters ranging in cost from $5,000 for smaller engines to $20,000 for
larger engines to be economically feasible, particularly given the
significant reduction these filters can achieve.
In the ANPRM, MSHA asked for comments on the appropriate role for
respirators. Most commenters indicated that respirators with some
restriction on their use should be permitted as a means of compliance
with the DPM limits. Some commenters disagree on the types of
restrictions that MSHA should place on their use, while other
commenters believe that PPE may be far more effective in protecting
miners from suspected DPM health effects than any available and
feasible engineering control technology. According to still other
commenters, respirators are uncomfortable and difficult to properly use
over an extended period of time. They restrict visibility and create
breathing resistance, thereby causing an additional hazard to miners.
Finally, MSHA was notified that if the final rule allows respirators at
all, such respirators should only be used with approval of the
Secretary, and only as a supplemental control for other feasible
controls.
Generally, commenters agreed with proposing MSHA's current
hierarchy of controls for reducing miners' exposures to DPM. Some
commenters to the ANPRM stated that MSHA properly prohibited the use of
PPE in the current rule and no change should be made to this provision.
Others stated that MSHA should state and enforce its preference for
engineering controls rather than personal protective equipment, and
that standard industrial hygiene practice supports this position. In
response to these commenters, MSHA agrees that engineering controls
should be included in the first tier of the agency's methods of
compliance. The proposed rule reflects this position but does not place
preference for engineering controls over use of administrative controls
for reducing miners' exposure to DPM. Mine operators would be required
to use all feasible engineering and administrative controls as a first
response to miners' overexposures. MSHA intends for mine operators to
have the flexibility to choose to start with engineering or
administrative controls, or a combination of both, as the control
method that best suits their circumstances.
Engineering controls are very effective in altering the sources of
miners' DPM exposures in the underground mining environment, thereby
decreasing DPM exposures. Unlike respiratory protection, engineering
controls do not depend upon individual performance or direct human
involvement to function. Based on its observations and experience in
underground metal and nonmetal mines, MSHA continues to believe that
feasible engineering and administrative controls exist to adequately
address most DPM overexposures to the interim limit. However, MSHA is
not persuaded that all DPM overexposures can be eliminated through
implementation of feasible engineering and administrative controls
alone, and that extra protective measures should be taken to protect
miners in such circumstances.
Some commenters suggested that various commercially available
respirators, including those with filtering facepieces, were suitable
for protection against particles smaller than DPM, and would therefore
be suitable for DPM as well. NIOSH recommended that respirators used
for protection against DPM have an R-100 or P-100 certification per 42
CFR part 84. NIOSH recommended against using N-rated respirators since
diesel exhaust contains oil, and aerosols containing oil can degrade
the performance of N-rated filters. MSHA agrees.
Proposed Sec. 57.5060(d)(1) would require that respirators be
NIOSH certified as a high-efficiency particulate air (HEPA) filter,
certified per 42 CFR part 84 (approval of Respiratory Protection
Devices) as 99.97% efficient, or certified by NIOSH for diesel
particulate matter. Proposed Sec. 57.5060(d)(2) would require that
non-powered, negative-pressure, air purifying, particulate-filter
respirators shall use an R- or P-series filter or any filter certified
by NIOSH for diesel particulate matter. The proposal further specifies
that R- series filters shall not be used for longer than one work
shift.
NIOSH also recommended that combination filters capable of removing
both particulates and organic vapor be specified, since organic vapors
and gases can be adsorbed onto DPM. The proposal does not require
respirators to be certified for organic vapor because MSHA does not
have data substantiating that a DPM overexposure would necessarily
indicate an associated overexposure to organic vapors. If simultaneous
sampling for DPM and organic vapors indicate overexposure to both
contaminants, any subsequent citation(s) relating to the overexposures
would require that respirators be used and equipped with a filter or
combination of filters rated for both DPM and organic vapors.
MSHA also asked for information as to whether mine operators should
be required to implement a written respiratory protection program when
miners must wear respiratory protection. Commenters were divided on
this issue. Some commenters stated that MSHA should require that the
respiratory protection program be in writing. NIOSH recommended in its
comments that ``mine operators be required to have a written
respiratory protection program, analogous to that required by OSHA for
general industry in 29 CFR 1910.134 Respiratory protection, that is
work-site specific and includes administration by a trained program
administrator, respirator selection criteria, worker training, a
program to determine that the workers are medically able to use
respiratory protective equipment, and provisions for regular evaluation
of the program's effectiveness.''
[[Page 48712]]
Other commenters opposed a written program. MSHA requests the
mining community to submit further information for justifying a written
respiratory protection program, including cost data and benefits to
miners' health.
The proposed standard is based on the 1969 ANSI documentation that
has been updated several times since the air quality standards were
promulgated in 1973 (30 CFR 56/57.5005). The ANSI, nevertheless,
recommended in its 1969 version, as well as in subsequent versions,
that a standard respiratory protection program should include written
procedures that address implementation information such as respirator
selection, fit testing procedures, cleaning and sanitizing procedures,
all of which are critical to an appropriate program. MSHA invites
further comments on whether the final DPM rule should include
provisions for a written respiratory protection program. Comments
should address health benefits for miners, projected paperwork burden
and compliance costs to the metal and nonmetal underground mining
industry, and should include supporting data.
MSHA also received comments on the need for including a requirement
for operators to have a miner medically examined before that miner
could be required to work in an area where respiratory protection would
be required. In addition, some commenters asked the agency to protect
miners' jobs by implementing the requirements of Sec. 101(a)(7) of the
Mine Act. Section 101(a)(7) of the Mine Act establishes the statutory
authority for MSHA to promulgate medical surveillance and transfer of
miner requirements in order to prevent the miner from being exposed to
health hazards. This provision of the Mine Act states, in pertinent
part:
Where appropriate, such mandatory standard shall also prescribe
suitable protective equipment and control or technological
procedures to be used in connection with such hazards and shall
provide for monitoring or measuring miner exposure at such locations
and intervals, and in such manner so as to assure the maximum
protection of miners. In addition, where appropriate, any such
mandatory standard shall prescribe the type and frequency of medical
examinations or other tests which shall be made available, by the
operator at his cost, to miners exposed to such hazards in order to
most effectively determine whether the health of such miners is
adversely affected by such exposure. Where appropriate, the
mandatory standard shall provide that where a determination is made
that a miner may suffer material impairment of health or functional
capacity by reason of exposure to the hazard covered by such
mandatory standard, that miner shall be removed from such exposure
and reassigned. Any miner transferred as a result of such exposure
shall continue to receive compensation for such work at no less than
the regular rate of pay for miners in the classification such miner
held immediately prior to his transfer. In the event of the transfer
of a miner pursuant to the preceding sentence, increases in wages of
the transferred miner shall be based upon the new work
classification.
Currently, MSHA standards do not require medical transfer of metal
and nonmetal miners. Existing standards at 30 CFR 56/57.5005(b) for
control of miners' exposure to airborne contaminants require that mine
operators establish a respiratory protection program consistent with
the ANSI Z88.2-1969 ``American National Standard for Respiratory
Protection'' which includes medical determinations for potential
respirator wearers. MSHA standards at 30 CFR part 90 address medical
removal for coal miners and provide miners with a medical examination
and an opportunity to transfer to an area of the mine having lower dust
levels, at the same level of pay, when the miner has x-ray evidence of
the development of pneumoconiosis.
OSHA acknowledges within its current standards addressing
respiratory protection at 29 CFR 1910.134(e) that use of a respirator
may place a physiological burden on workers while using them. At a
minimum, OSHA requires employers to provide medical evaluations before
an employee is fit tested or required to use respiratory protection.
Employers are required to have a physician or other licensed health
care professional have the worker complete a questionnaire, or in the
alternative, conduct an initial medical examination in order to make
the determination. If the worker has a positive response to certain
specified questions, the employer must provide a follow-up medical
examination. The questionnaire is contained in the body of the OSHA
rule. The preamble to the OSHA final rule states:
Specific medical conditions can compromise an employee's ability
to tolerate the physiological burdens imposed by respirator use,
thereby placing the employee at increased risk of illness, injury,
and even death (Exs. 64-363, 64-427). These medical conditions
include cardiovascular and respiratory diseases (e.g., a history of
high blood pressure, angina, heart attack, cardiac arrhythmias,
stroke, asthma, chronic bronchitis, emphysema), reduced pulmonary
function caused by other factors (e.g., smoking or prior exposure to
respiratory hazards), neurological or musculoskeletal disorders
(e.g., ringing in the ears, epilepsy, lower back pain), and impaired
sensory function (e.g., a perforated ear drum, reduced olfactory
function). Psychological conditions, such as claustrophobia, can
also impair the effective use of respirators by employees and may
also cause, independent of physiological burdens, significant
elevations in heart rate, blood pressure, and respiratory rate that
can jeopardize the health of employees who are at high risk for
cardiopulmonary disease (Ex. 22-14). One commenter (Ex. 54-429)
emphasized the importance of evaluating claustrophobia and severe
anxiety, noting that these conditions are often detected during
respirator training. [See 63 FR 1152, 01/08/1998]
MSHA seeks information from the public as to whether the final rule
should include requirements for medical examination and transfer of
miners under the proposed DPM respiratory protection standard.
Commenters should also submit cost implications of such a program and
other related data.
The Agency also considered whether mine operators should be
required to apply in writing to the Secretary for approval to use
respiratory protection. Some commenters recommended requiring approval
by the Secretary before respiratory protection should be permitted as a
means of compliance with the applicable DPM limit, but MSHA was not
persuaded that such a step would be necessary and MSHA's proposed Sec.
57.5060(d) does not include this recommendation. Respiratory protection
functions as a supplemental control. Operators must have ready access
to respirators when they must be used as is the case where the agency
has allowed metal and nonmetal mine operators to do so for many years
under MSHA's air quality standards. Moreover, the proposed control plan
requirements in Sec. 57.5062 and the application for extension in
Sec. 57.5060(c) would effectively require that mine operators specify
when they plan to use respirators to control a miner's DPM exposure.
MSHA, therefore, would know when mine operators intend to use
respirators as an interim measure until compliance can be achieved
through the application of engineering and administrative controls.
Further, when a mine operator is issued a citation under proposed Sec.
57.5060(d) for a miner's exposure exceeding the applicable DPM limit,
and the mine operator intends to use respiratory protection as an
interim control measure, MSHA would make certain that a respiratory
protection program is established and appropriate respirators are used
in accordance with Sec. 57.5005(a), (b) and proposed paragraphs Sec.
57.5060(d)(1) and (d)(2) concerning filter selection for air-purifying
respirators. Accordingly, this requirement can be deleted from the
[[Page 48713]]
existing rule without reducing protection to the miners.
D. Section 57.5060(e)
Existing Sec. 57.5060(e) prohibits mine operators from using
personal protective equipment (respirators) to comply with the DPM
concentration limit except under specific circumstances and only with
the advance approval of the Secretary based on an application submitted
by the mine operator. The effect of this provision would be to require
mine operators, in most situations, to control DPM concentrations by
implementing engineering and work practice controls, with limited
respirator usage as provided under Sec. 57.5060(d).
MSHA emphasizes that the hierarchy of controls presupposes that
certain types of industrial hygiene controls are inherently superior to
other types of controls in reducing or eliminating hazardous exposures.
Preference is given to controls that remove or eliminate the hazard
from the work place. Engineering controls and changes in work practices
that remove or eliminate the hazard are therefore the preferred methods
for controlling hazardous exposures, and in accordance with the
principle of hierarchy of controls, must be implemented first before
resorting to the use of personal protective equipment as a means of
compliance. Personal protective equipment is considered an acceptable
control option only after all feasible engineering and administrative
controls have been fully implemented. Under the hierarchy of controls
concept, if engineering and administrative controls alone are not
capable of reducing exposures to the applicable limit, these controls
would need to be used and maintained, but in addition, the mine
operator would be required to provide appropriate personal protective
equipment to affected miners and would have to ensure the equipment is
properly used.
Engineering controls, in both the existing rule and the proposal,
are meant to refer to controls that reduce or remove the DPM hazard
from the workplace by applying such methods as substitution, isolation,
interception, enclosure, and ventilation. In the existing rule,
administrative controls were uniquely defined as ``worker rotation''
and prohibited as an acceptable DPM control method because it fails to
eliminate the exposure hazard and results in placing more miners at
risk. In the proposal, this unique definition is removed and
administrative controls are meant to refer to the historically
recognized controls such as specified changes in the way work tasks are
performed that reduce or eliminate the hazard. Worker rotation is then
specifically prohibited as an administrative control in proposed Sec.
57.5060(e).
Since existing Sec. 57.5060(e) provided certain exceptions to the
prohibition on the use of personal protective equipment, MSHA does not
believe that its proposed revisions will result in significantly
greater respirator usage or decrease the level of protection afforded
to miners. The Agency's proposal, therefore, serves primarily to
simplify the understanding of the rule's requirements for controlling
DPM exposures, to achieve consistency with MSHA's other exposure-based
rules for metal and nonmetal mines, and to reduce unnecessary
paperwork.
E. Section 57.5061(a)
Under existing Sec. 57.5061(a), the Secretary would have
determined compliance with ``an applicable limit on the concentration
of diesel particulate matter pursuant to Sec. 57.5060.'' In accordance
with the DPM settlement agreement, the Agency proposes that Sec.
57.5061(a) be changed to specify that MSHA would determine compliance
with ``the PEL''. MSHA is proposing to replace the term Aconcentration
limit'' in this section with the term ``PEL'' to reflect that MSHA
proposes to enforce a personal exposure limit to limit miners' exposure
to DPM. These are conforming changes and do not result in a decrease of
protection to the miners.
F. Section 57.5061(b)
Compliance determinations under existing Sec. 57.5061(b) are based
on total carbon measurements. MSHA is proposing that compliance
determinations made under Sec. 57.5061(b) would be based on elemental
carbon measurements instead of total carbon in accordance with the
proposed change in the interim limit in Sec. 57.5060. Copies of the
NIOSH 5040 Analytical Method can be obtained at www.cdc.gov/niosh, or
by contacting MSHA's Pittsburgh Safety and the Health Technology
Center, P.O. Box 18233, Cochrans Mill Road, Pittsburgh, PA 15236.
G. Section 57.5061(c)
Under existing Sec. 57.5061(c), the Secretary would have
determined the appropriate sampling strategy for conducting compliance
sampling utilizing personal sampling, occupational sampling, or area
sampling, based on the circumstances of a particular exposure. The
Agency proposes that Sec. 57.5061(c) be changed to specify that only
personal sampling would be utilized for compliance determination.
The Agency believes that personal sampling alone will result in an
accurate determination of miner exposure to DPM. Proposed Sec.
57.5060(a) establishes a DPM limit that specifically relates to the
exposure of miners to DPM. Since the proposed limit relates to the
exposure of miners, the appropriate sampling method to determine
compliance is personal sampling. In this respect, the proposed rule's
sampling method for compliance determination is consistent with the
Agency's longstanding practice of utilizing personal sampling to
determine compliance with exposure limits for airborne contaminants in
the metal and nonmetal sector.
Under proposed Sec. 57.5061(b), MSHA would utilize elemental
carbon as the surrogate for DPM sampling. This is a conforming change
in the paragraph. Personal sampling allows for the accurate
determination of DPM exposure when elemental carbon is utilized as the
DPM surrogate.
The Agency anticipates several benefits of standardizing personal
sampling as the compliance sampling method. MSHA expects that mine
operators and miners are already familiar with personal sampling, since
MSHA utilizes it routinely when compliance sampling for noise, dust,
and other airborne contaminants. Utilizing personal sampling eliminates
possible disputes that could have arisen over whether an area sample
was obtained ``where miners normally work or travel.'' Mine operators
who choose to conduct environmental monitoring for DPM under Sec.
57.5071 using MSHA's compliance sampling method will not need to
anticipate which sampling method MSHA would most likely have selected,
personal, area, or occupational, based on the circumstances of a
particular exposure. Personal sampling avoids situations where area
sampling is intended to capture the exposure of a particular miner for
most or all of the work shift, but that miner moves to a new location
during the shift. Personal sampling for elemental carbon avoids the
problem of determining compliance for an equipment operator who is a
smoker and who works inside an enclosed cab. Under the existing rule,
this miner could not be sampled inside the cab due to interference from
tobacco smoke, and area sampling outside the cab would not capture that
miner's DPM exposure.
MSHA received numerous comments in response to the ANPRM concerning
the proposed elimination of area and occupational sampling. Most
supported
[[Page 48714]]
the change for the reasons expressed above. One commenter observed:
We agree that personal sampling more accurately measures
personal exposure. However, area sampling can also be useful for
checking the reliability of personal sampling, and the degree to
which that sampling is representative. Area sampling can also
provide important information about the quality of compliance plans.
MSHA should retain the ability to collect area samples for such
purposes, and to require that operators collect them, even if area
samples cannot, in themselves, trigger a citation.
The Agency agrees that personal sampling is more representative of
personal exposure, which is why the change to personal sampling for
compliance determinations is being proposed. The Agency also agrees
that area sampling can be a useful tool for quantifying DPM
concentrations at specific locations in a mine, which can greatly
facilitate evaluation of DPM controls. MSHA has conducted extensive
area sampling for DPM to assist Agency personnel, mine operators, and
miners to better understand DPM baseline conditions in mines, and to
evaluate the effectiveness of various DPM controls. MSHA intends to
continue to conduct area sampling for DPM as necessary, but on a
compliance assistance basis only, and not for compliance determinations
or enforcement.
A few commenters were opposed to the elimination of area and
occupational sampling for compliance determination. Two commenters
suggested that relying on personal sampling alone would enable a mine
operator to influence the sampling result to the mine operator's
advantage by re-assigning a miner being sampled to an area with lower
DPM levels. MSHA believes that although a mine operator may attempt to
defeat compliance sampling by re-assigning the miner being sampled,
MSHA's existing enforcement authority is adequate to ensure a valid and
representative sample can nonetheless be obtained.
If the miner being sampled for DPM is re-assigned to a different
workplace with lower DPM levels, or the miner's DPM exposure is
deliberately manipulated by some other means, such as by withdrawing a
``dirty'' piece of equipment from the area where the miner is working,
the inspector has the authority to investigate the circumstances, and
invalidate the sample if the inspector determines that the miner's
workday was not ``normal.'' In egregious cases, where there is clear
indication of intent and proof, the inspector may cite the mine
operator under 103(a) of the Mine Act for impeding an inspection. In
either case, sampling may be conducted subsequently to obtain a valid
and representative sample of that miner's DPM exposure.
One commenter suggested that personal sampling is not appropriate
for miners who work inside enclosed cabs, because although they may be
protected against DPM, other downstream miners who do not work inside
enclosed cabs would not be protected. MSHA believes that the compliance
status of any miner can be determined by personal sampling, whether
they work in an enclosed cab or not. Personal sampling of the miner in
an enclosed cab can determine whether the cab air filtration system or
other DPM controls are adequate to maintain compliance for that miner.
Downstream miners who do not work in enclosed cabs and who are
suspected of high DPM exposures can also be sampled, and in accordance
with MSHA's health sampling policy that targets miners with the highest
exposures for sampling, the inspector would likely do so.
Several comments were also received that responded specifically to
the questions asked in the ANPRM relating to existing Sec. 57.5061(c)
and proposed changes.
(a) What would be the cost implications for mine operators to
conduct personal sampling of miners' DPM exposures if EC is the
surrogate?
One commenter indicated that costs are secondary to whether the
policy of conducting personal sampling for compliance determination is
reasonable. Other comments suggested no change in expected costs
because the NIOSH Method 5040 is in place at several commercial labs.
Several commenters noted that costs may be lower if EC is the surrogate
due to ``fewer false readings and contaminated samples.'' On the whole,
MSHA believes valid and representative samples can be obtained through
personal sampling, and MSHA does not expect differences in sampling
cost, if any, to be significant.
(b) What experience do mine operators have with DPM sampling and
analysis?
The commenters indicated that mine operators' experience with DPM
sampling and analysis varies widely across the underground metal and
nonmetal mining industry. Some mine operators, especially those that
have been parties to the DPM litigation and/or involved in the 31-Mine
Study, have acquired considerable experience, while many other
operators have had little or no experience. Several commenters
mentioned that mining company health and safety staff capable of
conducting DPM sampling ``are overburdened with other MSHA initiatives
(HazCom, noise, silica) and will not be able to complete the required
DPM tasks.'' These commenters recommended that AMSHA should provide in-
mine training, sampling assistance [and] outreach meetings'' and that
MSHA health staff should help mine operators that lack DPM sampling
experience ``without enforcement, by providing comprehensive in-mine
training and sampling assistance.''
MSHA largely agrees that many mine operators are unfamiliar with
MSHA's DPM sampling and analytical methods. Accordingly, MSHA intends
to provide numerous opportunities for mine operators and miners to
obtain training on DPM sampling. MSHA will target these compliance
assistance training opportunities to small mine operators in
particular. MSHA conducted a 3-day, in-mine, hands-on DPM sampling
workshop at an underground limestone mine near Louisville, KY in
December 2002, and other similar workshops are planned.
MSHA has also posted information on its Web site relating to the
specialized DPM sampling cassette with integral submicron impactor.
Also posted on the MSHA web site are a Compliance Guide on the standard
itself, which includes considerable information about sampling, the
draft chapter from MSHA's Metal and Nonmetal Health Inspection
Procedures Handbook detailing the compliance sampling procedures that
MSHA inspectors will follow, and the field notes form that MSHA
inspectors will use to document DPM compliance sampling. All of this
information is also available in hardcopy form for mine operators and
miners who do not have internet access. MSHA intends to develop and
provide additional DPM sampling-related compliance assistance materials
as needed to mine operators and miners in both hard-copy form and on
its Web site.
As a result of some of the changes in the rule language that have
been proposed through this rulemaking, MSHA's DPM compliance sampling
procedures will conform more closely to existing MSHA sampling
practices for dust and other airborne contaminants. As a consequence,
mine operators that have had no previous experience with DPM sampling,
but have had experience with, or at least knowledge of, MSHA respirable
dust sampling, will discover they have very little more to learn.
Except for the sample filter cassette itself, the mechanics of DPM
sampling will be almost identical to respirable
[[Page 48715]]
dust sampling. For example, the same pump and sampling train are used
(sample pump, hose, cyclone holder, Dorr-Oliver 10 mm nylon cyclone),
and the pumps must be pre- and post-calibrated at the same 1.7 liters
per minute flow rate. Sampling for both respirable dust and DPM is for
the full shift, and the same chain-of-custody procedures must be
followed for handling the cassettes. For both respirable dust and DPM,
the miners with the highest expected exposure will be targeted for
sampling, and much of the same information will need to be documented
in the sampler's field notes (mine, date, person conducting sampling,
person being sampled, sources of exposure, controls used, etc.).
As with respirable dust sampling, compliance sampling, for DPM
would be personal rather than a combination of personal, area, and
occupational. Also, since the surrogate for DPM would be EC instead of
TC, the sampling complications associated with avoiding OC interferents
are eliminated (e.g. sampling too close to smokers, sampling too close
to sources of drill oil mist, etc.).
Mine operators should already be familiar with MSHA's sampling
procedures for respirable dust. Because respirable dust sampling and
DPM sampling will be so similar, and because numerous DPM sampling
training opportunities will be made available across the industry, MSHA
expects few if any mines will be unable to conduct their own DPM
sampling or to comply with the DPM sampling requirements of this
standard. Regarding the issue of mine operator DPM sampling being an
added burden on mine safety and health staff, MSHA acknowledges that it
is almost unavoidable that some staff time will need to be allocated to
DPM sampling. However, MSHA does not believe that this added burden
will be significant for most mines. A specific DPM monitoring schedule
is not included in the standard. Mine operators are required to monitor
as often as necessary to verify continuing compliance. Once compliance
has been verified, MSHA would not anticipate that extensive additional
monitoring would be required. However, if conditions affecting DPM
emissions or in-mine DPM concentrations change significantly, such as
by the addition of new equipment or changes in the ventilation system,
the mine operator would be expected to verify that these changes have
not resulted in DPM overexposures.
(c) Is there experience with DPM sampling in other industries and
other countries?
One commenter suggested that many coal mine operators know enough
about sampling to influence the outcome, and that MSHA should therefore
use a combination of personal, area and occupational sampling to
properly evaluate the levels of DPM in the ambient atmosphere. However,
as noted above, MSHA believes it has sufficient enforcement authority
to appropriately deal with any incidents of deliberate sample
tampering, should they arise.
Other commenters were aware that a group in Canada (DEEP) has been
researching technology to reduce DPM in occupational settings and
mentioned the EPA studies on diesel exposure. They did not feel the EPA
sampling was applicable to occupational exposure assessments. Some of
them felt that MSHA should stay its DPM enforcement until the DEEP
study and NIOSH research yielded more data.
MSHA is also aware of these studies and considered them during this
rulemaking. The Agency believes that there is sufficient information
available to support feasibility of the proposed 308EC[mu]g/
m3 interim limit, as discussed previously in this preamble
under Technological and Economic Feasibility. As a result of the
settlement agreement, MSHA allowed mine operators to take an additional
year after the effective date of the existing interim DPM concentration
limit during which mine operators could begin to install appropriate
controls to reduce DPM concentrations.
H. Section 57.5062 Diesel Particulate Matter Control Plan
Existing Sec. 57.5062 requires mine operators to establish a DPM
control plan, or modify the plan, upon receiving a citation for an
overexposure to the concentration limit in Sec. 57.5060. A single
citation triggers the plan. A violation of the plan is citable without
consideration of the current DPM concentration level. The operator must
demonstrate that the new or modified plan will be effective in
controlling the DPM concentration to the limit. The existing rule also
sets forth a number of other specific details about the plan, including
a description of controls that the operator will use to maintain the
DPM concentration; a list of diesel-powered units maintained by the
mine operator; information about each unit's emission control device;
demonstration of the plan's effectiveness; verification sampling;
retention of a copy of the control plan at the mine site for the
duration of the plan plus one year; and a plan duration of three years
from the date of the violation resulting in establishment of the plan.
In accordance with the DPM settlement agreement, MSHA agreed to
publish a notice of proposed rulemaking to revise current Sec.
57.5062. The settlement agreement, however, did not specify how MSHA
should revise this section. In the ANPRM, MSHA requested comments and
ideas from the mining community as to how the control plan requirements
should be revised.
Some commenters stated that there was no reason for MSHA to change
this provision. These commenters emphasized that control plans are good
industrial hygiene practice and should be the standard of practice for
the mining industry. Other commenters felt strongly that the control
plan was unnecessary in light of MSHA's intent to propose its long-
standing hierarchy of controls for metal and nonmetal exposure-based
standards. Some commenters opposed to a control plan stated that the
purpose of the existing control plan was to prevent chronic excursions
above the allowable concentration limit rather than allowing these
excursions as part of the daily DPM control scheme. These commenters
believed that the controls in place are sufficient to protect miners
from DPM overexposures without introducing a cumbersome plan approval
process. They further stated that MSHA could accomplish this through
existing mechanisms such as section 104(b) of the Federal Mine Safety
and Health Act of 1977 (30 U.S.C. 814) sanctions currently employed for
failure to abate violations.
Other commenters opposing a control plan stated that not only was
it unnecessary, but it also imposed upon mine operators unwarranted
costs. They suggested that MSHA assess compliance by the operator's
environmental monitoring and MSHA compliance sampling. Furthermore,
following a hierarchy of controls approach would ensure miners'
protection during non-compliance. They stated that formal plans would
add little or nothing to established systems.
Some other comments that MSHA received on its question of whether
to retain the control plan in a final rule included two which stated
that a control plan was not necessary if mine operators put forth good-
faith efforts in complying with the standard; and, that MSHA could
monitor an operator's good faith efforts and obtain supporting
documentation during regular inspections.
MSHA also asked in its ANPRM whether there was any benefit derived
from retaining the control plan since the Agency intended to propose
its long-
[[Page 48716]]
standing hierarchy of controls for controlling miners' exposures to
DPM. In response, some commenters felt that substituting the hierarchy
of controls for a DPM control plan would be unacceptable.
Commenters in favor of retaining the control plan stated that it
requires mine operators to develop an organized written approach to
controlling exposure and does not preclude developing a policy on the
hierarchy of controls. The effectiveness of the standard depends on
preparing and following a detailed control plan. Commenters believe
that control plans are cost effective by forcing operators to control
DPM efficiently. Control plans help MSHA determine if the company is
acting in good faith. They help compliance assistance and provide
information for the miners' representative to participate in safety and
health programs. Commenters believe that an alternative would be a plan
with more specific requirements for maintenance, vehicle inspection,
emission controls, and fuel quality.
Although some commenters believe that a control plan is
unnecessary, MSHA is proposing to retain this requirement. As expressed
in the preamble to the existing rule, MSHA's rationale for requiring a
DPM control plan is derived from the rule's approach to setting control
requirements. MSHA recognizes that every mine covered by this rule has
unique conditions and circumstances that affect DPM exposures such as
the number and sizes of diesel-powered engines, idling duration and
frequency, emission controls, diesel maintenance practices, and
ventilation.
The Agency is interested in developing uniform DPM control
requirements that are effective in protecting miners' health and
practical for the mining industry to implement. MSHA acknowledges that
there are numerous approaches in accomplishing this objective.
Operators may choose to control DPM emissions by filtering the
diesel-powered equipment; installing cleaner-burning engines;
increasing ventilation; improving fleet management; utilizing
administrative controls; or using a variety of other readily available
controls, all without consulting with, or seeking approval from MSHA.
Given the wide variety of options and alternatives available to
operators for controlling DPM exposures, the Agency believes that it
needs to know what strategy the operator will be utilizing to control
DPM exposures, particularly if compliance cannot be achieved within a
short period of time.
Although MSHA is proposing to retain the control plan, the Agency,
however, requests further comment on whether the control plan should be
retained since MSHA is also proposing a DPM rule that includes
hierarchy of controls. It is not MSHA's intent to duplicate compliance
requirements in this rulemaking.
In proposed Sec. 57.5062, MSHA would require an operator to
establish a written control plan, or modify an existing control plan,
if it will take the mine operator more than 90 calendar days from the
date of a citation to achieve compliance. A single violation of the PEL
would continue to be the basis for triggering the requirement for a
control plan. The control plan would remain in effect for a one-year
period following termination of the citation. Mine operators would also
be required to include in the plan a description of the controls that
will be used to reduce the miners' exposures to the PEL. MSHA intends
to cite for a violation of the plan without regard for a miner's
exposure to the PEL. MSHA believes that these requirements would prompt
mine operators to properly maintain existing DPM controls at their
mines.
Existing Sec. 57.5062(e)(1) specifies that the control plan remain
in effect for 3 years from the date of the violation which caused it to
be established. MSHA asked the mining community for input regarding the
appropriate duration of a revised control plan. Commenters responded
that if the violation was minor and easily corrected, that the control
plan could be simple in content and brief in duration.
MSHA believes that it is important to maintain the plan as long as
the operator is working to reduce DPM exposures to the applicable
limits. However, once the operator achieves compliance, MSHA believes
that the need for maintaining a plan decreases. Accordingly, MSHA is
proposing in Sec. 57.5062(a) that a plan remain in effect for a period
of one year after the citation is terminated.
MSHA does not intend to include a monitoring provision under the
control plan because generic monitoring provisions in Sec. 57.5071
would continue to apply during the existence of a control plan. MSHA
expects mine operators to monitor as frequently as necessary to confirm
that controls are effective in reducing the miners' exposure to the
PEL. MSHA seeks further comment on the duration of time that the
control plan should continue in effect once a citation for overexposure
to DPM is terminated.
Existing Sec. 57.5062(b) requires that the operator include in the
plan a description of the controls that will be used to maintain the
concentration of diesel particulate matter to the applicable limit
specified by Sec. 57.5060, a list of the diesel-powered units
maintained by the mine operator, and information about each unit's
emission control device. MSHA is proposing to simplify the contents of
the plan and require that it only include a description of the controls
the operator will use to reduce the miners' exposures to the PEL. MSHA
believes that there could be a wide variety of information that
operators may want to include in their plan, and that it is not
beneficial to specify a few while leaving out many others. Therefore,
MSHA intends to provide maximum flexibility of compliance for mine
operators. This description should include all controls that the
operator is using to reduce miners' exposures, including engineering
controls, administrative controls, personal protective equipment, and
maintenance procedures, to name a few.
Existing Sec. 57.5062(e)(3) requires an operator to modify a DPM
control plan during its duration as required to reflect changes in
controls, mining equipment or circumstances. MSHA did not receive any
comments in response to its ANPRM regarding modifications to the plan.
MSHA is proposing to retain this particular requirement consistent
with the existing rule, with one minor modification. Proposed Sec.
57.5062(c) would require that the operator modify the plan to reflect
changes in controls, mining equipment, or continuing noncompliance.
This would require mine operators to modify their plan when the results
of sampling conducted by MSHA or the mine operator indicates that a
miner's exposure exceeds the PEL. MSHA does not believe that this
change will result in an increase in compliance costs or paperwork. The
change is intended to clarify the existing provision. MSHA did not
receive comments to its ANPRM on this issue.
Existing Sec. 57.5062(a)(2) requires that the operator demonstrate
that the new or modified DPM control plan parameters control the
concentration of DPM to the concentration limit specified in Sec.
57.5060. Mine operators must demonstrate plan effectiveness by
monitoring, using the measurement method specified by Sec. 57.5061(b)
which addresses compliance determinations. Such monitoring must be
sufficient to verify that the plan will control the concentration of
DPM to the limit under conditions that can be reasonably anticipated in
the mine. Further, the operator must retain a copy of each
[[Page 48717]]
verification sample result at the mine site for five years. Monitoring
must be conducted in addition to, and not in lieu of, any other
sampling the Secretary performs.
MSHA is proposing to delete the requirements for plan verification
monitoring. The Agency believes that such monitoring is adequately
addressed under Sec. 57.5071, which requires mine operators to monitor
in order to determine, under conditions that can be reasonably
anticipated in the mine, whether DPM exposures exceed the applicable
limits specified in Sec. 57.5060. No monitoring frequency is specified
under existing DPM monitoring requirements. MSHA believes that these
requirements provide an effective alternative to the existing plan
verification sampling requirements. Further, MSHA will conduct
additional compliance sampling whenever the Agency suspects that
miners' exposures to DPM are not being maintained to the PEL.
The Agency also believes that operator sampling may not always be
necessary to determine if controls are being used or maintained. The
proposed control plan would require that mine operators specifically
describe the controls being used to reduce the miners' exposures to the
DPM limit. If MSHA finds during an inspection that specified controls
were missing or not being maintained, MSHA has existing enforcement
tools to require that mine operators correct the situation.
MSHA is proposing to retain the requirement that mine operators
keep a copy of the current control plan at the mine site for its
duration. Existing Sec. 57.5062(f) specifies that an operator's
failure to comply with the provisions of the diesel particulate matter
control plan in effect at a mine, or to conduct required verification
sampling is a violation of this part without regard for the
concentration of diesel particulate matter that may be present at any
time. MSHA intends to adopt this position and cite mine operators for a
violation of the plan without consideration of a miner's exposure to
the DPM limit. The Agency is proposing to delete this requirement in
the rule language only and explain this enforcement position in the
preamble.
Existing Sec. 57.5062(d) requires the operator to provide access
to records maintained under this section to specified individuals and
agencies. The existing rule further requires the mine operator to
maintain a copy of the plan and the plan verification monitoring
results. As explained earlier in this preamble, MSHA does not believe
that verification monitoring is justified in a proposed rule. Pursuant
to Sec. 57.5071, MSHA has access to any record listed in the DPM rule,
including an operator's control plan. This access, among other things,
provides the Agency with the means to verify an operator's control plan
without requiring additional compliance from mine operators. Therefore,
MSHA intends to delete this requirement.
MSHA believes that this proposal would provide an alternative
method of protecting miners' health provided for under the existing
standard. MSHA is interested in providing compliance flexibility to
mine operators where such flexibility does not compromise miners'
health or safety. The Agency is proposing to retain the current
requirement for a control plan with modifications to eliminate
unnecessary requirements.
MSHA emphasizes that the proposed modifications do not compromise
miners' health or safety under Sec. 101(a)(9) of the Mine Act. Section
101(a)(9) provides: ``No mandatory health or safety standard
promulgated under this title shall reduce the protection afforded
miners by an existing mandatory health or safety standard.'' MSHA
interprets this provision of the Mine Act to require that all of the
health or safety benefits resulting from a new standard be at least
equivalent to all of the health or safety benefits resulting from the
existing standard when the two sets of benefits are evaluated as a
whole. Int'l Union v. Federal Mine Safety and Health Admin., 920 F.2d
960, 962-64 (D.C. Cir. 1990); Int'l Union v. Federal Mine Safety and
Health Admin., 931 F.2d 908, 911 (D.C. Cir 1991). The Agency believes
that the proposal meets this test.
I. Section 57.5071 Exposure Monitoring
Proposed Sec. 57.5071 would make conforming changes to the
existing requirements for mine operators to monitor DPM levels to be
consistent with the other changes being proposed. While the existing
rule limits DPM concentration in the mine, the proposed rule would
limit a miner's DPM exposure. Therefore, existing paragraph (a)
requiring the mine operator to monitor the concentration of DPM would
be revised to require mine operators to monitor a miner's full-shift
airborne exposure.
Similarly, existing paragraph (c) requiring mine operators to take
prompt corrective action when the concentration limit is exceeded would
be revised to substitute ``PEL'' for ``concentration limit.''
J. Section 57.5075 Diesel Particulate Records
Existing Sec. 57.5075(a) summarizes the recordkeeping requirements
of the DPM standards contained in Sec. Sec. 57.5060 through 57.5071.
Proposed Sec. 57.5075(a) would number the Diesel Particulate
Recordkeeping Requirements table within the section without changing
the requirements under existing Sec. 57.5075(a). MSHA intends to
delete table entries for existing Sec. 57.5060(d), approved plan for
miners to perform inspection, maintenance or repair activities in areas
exceeding the concentration limit, and Sec. 57.5062(c), compliance
plan verification sample results. MSHA intends to add the requirement
for maintaining a copy of the control plan for the duration of the plan
in accordance with proposed Sec. 57.5062(d). As a clarifying change to
the table, MSHA also intends to add the existing requirement for
posting notice of corrective action being taken under Sec. 57.5071(c).
X. Regulatory Impact Analysis
This part of the preamble reviews several impact analyses which the
Agency is required to provide in connection with its proposed
rulemaking. The full text of these analyses can be found in the
Agency's Preliminary Regulatory Economic Analysis (PREA).
A. Cost and Benefits: Executive Order 12866
Executive Order 12866 requires regulatory agencies to assess both
the costs and benefits of regulations. In making this assessment, MSHA
determined that although this final rule will not have an annual effect
of $100 million or more on the economy, and therefore is not a
significant regulatory action as defined by 3(f)(1) of E.O. 12866, the
rule meets the Sec. 3(f)(4) definition, that is, the rule may `` * * *
raise novel legal or policy issues arising out of legal mandates, the
President's priorities, or the principles set forth in this Executive
Order.'' MSHA completed a Preliminary Regulatory Economic Analysis
(PREA) which estimates both the costs and benefits of the rule. This
PREA is available from MSHA and is summarized below.
Table X-1 presents the total yearly compliance costs by provision
and mine size for the proposed revisions. All MSHA cost estimates are
presented in 2001 dollars. The proposed rule would result in a net cost
of $4,539 per year for underground metal and nonmetal mine operators.
This would be an average cost of $25 for each of the 182 underground
[[Page 48718]]
metal and non-metal mines that would be affected by this proposed rule.
Of these 182 mines, 65 have fewer than 20 workers, 113 have 20 to 500
workers; and 4 have more than 500 workers. The average cost per mine
for mines in these three size classes would be -$34 (a cost savings),
$58, and $58, respectively.
Table X-1.--Total Yearly Compliance Costs
----------------------------------------------------------------------------------------------------------------
Mine size
Provision ------------------------------------------------ Total
<20 20-500 500
----------------------------------------------------------------------------------------------------------------
Special Extensions 57.5060(c)................... $6,179 $21,117 $748 $28,044
Respirator Protection 57.5060(d)................ -2,569 -4,466 -158 -7,192
DPM Control Plan 57.5062........................ -5,826 -10,128 -359 -16,313
-----------------
Total....................................... -2,215 6,523 231 4,539
----------------------------------------------------------------------------------------------------------------
B. Regulatory Flexibility Act Certification
The Regulatory Flexibility Act (RFA) requires regulatory agencies
to consider a rule's economic impact on small entities. Under the RFA,
MSHA must use the Small Business Act definition of a small business
concern in determining a rule's economic impact unless, after
consultation with the SBA Office of Advocacy, and after opportunity for
public comment, MSHA establishes a definition which is appropriate to
the activities of the agency and publishes that definition in the
Federal Register. For the mining industry, SBA defines ``small'' as
having 500 or fewer workers. MSHA has traditionally considered small
mines to be those with fewer than 20 workers. To ensure that the rule
conforms with the RFA, MSHA analyzed the economic impact on mines with
500 or fewer workers and also on mines with fewer than 20 workers. MSHA
concluded that the rule will not have a significant economic impact on
a substantial number of small entities under either definition.
C. Unfunded Mandates Reform Act of 1995
For purposes of the Unfunded Mandates Reform Act of 1995, the rule
does not include any Federal mandate that may result in increased
expenditures of more than $100 million incurred by state, local, or
tribal governments, or by the private sector.
D. Paperwork Reduction Act of 1995 (PRA)
This proposed rule contains changes to two information collection
requirements, both of which were approved by the Office of Management
and Budget (OMB) as part of Information Collection No. 1219-0135, which
expires on September 30, 2004.
The proposed changes were submitted to OMB for review pursuant to
the PRA, as codified at 44 U.S.C. 3501-3520 and implemented by OMB in
regulations at 5 CFR part 1320. The PRA defines collection of
information as ``the obtaining, causing to be obtained, soliciting, or
requiring the disclosure to third parties or the public of facts or
opinions by or for an agency regardless of form or format.''
The proposed paperwork requirement changes are contained in
Sec. Sec. 57.5060 and 57.5062. There are burden hours and associated
costs that will occur only in the first year that the provision is in
effect, and there are burden hours and associated costs that will occur
every year the rule is in effect, starting with the first year
(``annual'' burden hours and costs). Due to different requirements in
these provisions for the interim and final limits, the effective dates
vary. In the first year, mine operators will incur a net of 1,047.78
burden hours and associated costs of $2,479. in year one.
In year two only, mine operators will incur 613.17 burden hours and
associated annualized costs of $1,776. There is a reduction of 931.96
burden hours occurring only in year three. The present value of the
cost savings associated with these burden hours is $6,343. Starting in
year three, there is a reduction in annual burden hours of 103.55. The
discounted value of the cost savings associated with these burden hours
is $3,738 annually. Mine operators will incur 613.17 annual burden
hours starting in year four. The discounted value of the cost
associated with these burden hours is $22,161 annually.
Included in these estimates are the time for reviewing
instructions, gathering and maintaining the data needed, and completing
and reviewing the collection of information. MSHA invites comments on:
(1) Whether any proposed collection of information presented here (and
further detailed in the Agency's PREA) is necessary for proper
performance of MSHA's functions, including whether the information will
have practical utility; (2) the accuracy of MSHA's estimate of the
burden of the proposed collection of information, including the
validity of the methodology and assumptions used; (3) ways to enhance
the quality, utility, and clarity of information to be collected; and
(4) ways to minimize the burden of the collection of information on
respondents, including through the use of automated collection
techniques, when appropriate, and other forms of information
technology.
The Agency has submitted a copy of this proposed rule to OMB for
its review and approval of these information collections. The complete
paperwork submission is contained in the Preliminary Regulatory
Economic Analysis and Preliminary Regulatory Flexibility Analysis
(PREA/PRFA) and includes the estimated costs and assumptions for each
proposed paperwork requirement (these costs are also included in the
Agency's cost and benefit analyses for the proposed rule). A copy of
the PREA/PRFA is available at http://www.msha.gov/regsinfo.htm. These
paperwork requirements have been submitted to the Office of Management
and Budget for review under section 3504(h) of the Paperwork Reduction
Act of 1995. Respondents are not required to respond to any collection
of information unless it displays a current valid OMB control number.
F. Executive Order 12630: Government Actions and Interference With
Constitutionally Protected Property Rights
This proposed rule is not subject to Executive Order 12630,
Government Actions and Interference with Constitutionally Protected
Property Rights, because it does not involve implementation of a policy
with takings implications.
G. Executive Order 12988: Civil Justice Reform
The Agency has reviewed Executive Order 12988, Civil Justice
Reform, and determined that the proposed DPM rule
[[Page 48719]]
would not unduly burden the Federal court system. The proposed rule has
been written so as to provide a clear legal standard for affected
conduct and has been reviewed carefully to eliminate drafting errors
and ambiguities.
H. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
In accordance with Executive Order 13045, MSHA has evaluated the
environmental health and safety effects of the proposed DPM rule on
children. The Agency has determined that the proposed rule would not
have an adverse impact on children.
I. Executive Order 13132: Federalism
MSHA has reviewed the proposed DPM rule in accordance with
Executive Order 13132 regarding federalism and has determined that it
would not have any federalism implications. The proposed rule would not
have substantial direct effects on the States, on the relationship
between the national government and the States, or on the distribution
of power and responsibilities among the various levels of government.
J. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
MSHA has determined that the proposed DPM rule would not impose
substantial direct compliance costs on Indian tribal governments.
K. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
In accordance with Executive Order 13211, the Agency has reviewed
proposed DPM rule for its energy impacts. The rule would have no effect
on the supply, distribution or use of energy.
L. Executive Order 13272: Proper Consideration of Small Business
Entities in Agency Rulemaking
In accordance with Executive Order 13272, MSHA has thoroughly
reviewed the proposed DPM rule to assess and take appropriate account
of its potential impact on small businesses, small governmental
jurisdictions, and small organizations. As discussed in Chapter V of
the PREA, MSHA has determined that the proposed rule would not have a
significant economic impact on a substantial number of small entities.
XI. References
Al-Humadi, N. H., et al., ``The Effect of Diesel Exhaust Particles
(DEP) and Carbon Black (CB) on Thiol Changes in Pulmonary Ovalbumin
Allergic Sensitized Brown Norway Rats'', Exp. Lung Res., 2002 Jul-
Aug; 28(5):333-49.
Boffetta, Paolo and Silverman, Debra T., ``A Meta-Analysis of
Bladder Cancer and Diesel Exhaust Exposure'', Epidemiology,
2001;12(1):125-130.
Biimlnger, J., et al., ``Mutagenicity of diesel exhaust particles
from two fossil and two plant oil fuels'', Mutagenesis, 2000
Sep;15(5):391-7.
Carero, Don Porto A., et al., ``Genotoxic Effects of Carbon Black
Particles, Diesel Exhaust Particles, and Urban Air Particulates and
Their Extracts on a Human Alveolar Epithelial Cell Line (A549) and a
Human Monocytic Cell Line (THP-1).'' Environ. Mol. Mutagen.,
2001;37(2):155-63.
Castranova V., et al., ``Effect of Exposure to Diesel Exhaust
Particles on the Susceptibility of the Lung to Infection'', Environ.
Health. Perspect., 2001 Aug;109 Suppl 4:609-12.
Chambellan, A., et al., ``Diesel particles and allergy: cellular
mechanisms'', Allerg. Immunol., 2000 Feb;32(2):43-8 (French).
Chow, et al., ``Comparison of IMPROVE and NIOSH Carbon
Measurements'', Aerosol Science and Technology, 2001;(34):23-34.
Dominici, Francesca, ``A Report to the Health Effects Institute:
Reanalyses of the NMMAPS Database'', October 31, 2002.
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List of Subjects in 30 CFR Part 57
Diesel particulate matter, Metals, Mine safety and health,
Reporting and recordkeeping requirements.
For the reasons set forth in the preamble, MSHA proposes to amend
Chapter I of Title 30 as follows:
1. The authority citation for part 57 continues to read as follows:
Authority: 30 U.S.C. 811 and 813.
2. Section 57.5060 is amended by revising paragraphs (a), (c)(1),
(c)(2), (c)(3), (c)(4), (d), and (e) and removing paragraphs (c)(5) and
(f) to read as follows:
Sec. 57.5060 Limit on concentration of diesel particulate matter.
(a) A miner's personal exposure to diesel particulate matter (DPM)
in an underground mine shall not exceed an average eight-hour
equivalent full shift airborne concentration of 308 micrograms of
elemental carbon per cubic meter of air (308EC [mu]g/
m3). [This interim permissible exposure limit (PEL) shall
remain in effect until the final DPM exposure limit becomes effective.]
* * * * *
(c)(1) If a mine requires additional time to come into compliance
with the applicable limits established in paragraphs (a) and (b) of
this section due to technological or economic constraints, the operator
of the mine may file an application with the district manager for a
special extension.
(2) The mine operator must certify on the application that the
operator has posted one copy of the application at the mine site for at
least 30 days prior to the date of application, and has provided
another copy to the authorized representative of miners.
(3) No approval of a special extension shall exceed a period of one
year from the date of approval. Mine operators may file for additional
special extensions provided each extension does not exceed a period of
one year. An application must include the following information:
(i) A statement that diesel-powered equipment was used in the mine
prior to October 29, 1998;
(ii) Documentation supporting that controls are technologically or
economically infeasible at this time to reduce the miner's exposure to
the DPM limit.
(iii) The most recent DPM monitoring results.
(iv) The actions the operator will take during the extension to
minimize exposure of miners to DPM.
(4) A mine operator must comply with the terms of any approved
application for a special extension, post a copy of the approved
application for a special extension at the mine site for the duration
of the special extension period, and provide a copy of the approved
application to the authorized representative of miners.
(d) The mine operator shall install, use, and maintain feasible
engineering and administrative controls to reduce a miner's exposure to
or below the DPM limit established in this section. When controls do
not reduce a miner's DPM exposure to the limit, controls are
infeasible, or controls do not produce significant reductions in DPM
exposures, controls shall be used to reduce the miner's exposure to as
low a level as feasible and shall be supplemented with respiratory
protection in accordance with Sec. 57.5005(a), (b), and paragraphs
(d)(1) and (d)(2) of this section.
(1) Air purifying respirators shall be equipped with the following:
(i) Filters certified by NIOSH under 30 CFR part 11 (appearing in
the July 1, 1994 edition of 30 CFR, parts 1 to 199) as a high
efficiency particulate air (HEPA) filter;
(ii) Filters certified by NIOSH under 42 CFR part 84 as 99.97%
efficient; or
(iii) Filters certified by NIOSH for diesel particulate matter.
(2) Nonpowered, negative-pressure, air purifying, particulate-
filter respirators shall use an R- or P-series filter or any filter
certified by NIOSH for diesel particulate matter. An R-series filter
shall not be used for longer than one work shift.
(e) Rotation of miners shall not be considered an acceptable
administrative control used for compliance with this section.
3. Section 57.5061 is revised to read as follows:
Sec. 57.5061 Compliance determinations.
(a) MSHA shall use a single sample collected and analyzed by the
Secretary in accordance with the requirements of this section as an
adequate basis for a determination of noncompliance with the DPM limit.
(b) The Secretary will collect samples of diesel particulate matter
by using a respirable dust sampler equipped with a submicrometer
impactor and analyze the samples for the amount of elemental carbon
using the method described in NIOSH Analytical Method 5040, except that
the Secretary also may use any methods of collection and analysis
subsequently determined by NIOSH to provide equal or improved accuracy
for the measurement of diesel particulate matter.
(c) The Secretary will use full-shift personal sampling for
compliance determinations.
4. Section 57.5062 is revised to read as follows:
Sec. 57.5062 Diesel particulate matter control plan.
(a) When it will take the operator more than 90 calendar days from
the
[[Page 48721]]
date of a citation for violating Sec. 57.5060 to achieve compliance,
the operator shall establish and implement a written plan to control
the miner's exposure. The plan shall remain in effect for a period of
one year after the citation is terminated.
(b) The plan must include a description of the controls the
operator will use to reduce the miner's exposure to the DPM limit.
(c) The operator must modify the plan to reflect changes in
controls, mining equipment, or continuing noncompliance.
(d) The operator must retain a copy of the plan at the mine site
for the duration of the plan.
5. Section 57.5071 is amended by revising the section heading and
by revising paragraphs (a) and (c) to read as follows:
Sec. 57.5071 Exposure monitoring.
(a) Mine operators must monitor as often as necessary to
effectively determine, under conditions that can be reasonably
anticipated in the mine, whether the average personal full-shift
airborne exposure to DPM exceeds the DPM limit specified in Sec.
57.5060.
* * * * *
(c) If any monitoring performed under this section indicates that a
miner's exposure to diesel particulate matter exceeds the DPM limit
specified in Sec. 57.5060, the operator must promptly post notice of
the corrective action being taken on the mine bulletin board, initiate
corrective action by the next work shift, and promptly complete such
corrective action.
* * * * *
6. Section 57.5075 is amended to revise paragraph (a) to read as
follows:
Sec. 57.5075 Diesel particulate records.
(a) Table 57.5075(a), ``Diesel Particulate Recordkeeping
Requirements'' lists the records the operator must retain pursuant to
Sec. Sec. 57.5060 through 57.5071, and the duration for which
particular records need to be retained.
Table 57.5075(a).--Diesel Particulate Recordkeeping Requirements
----------------------------------------------------------------------------------------------------------------
Record Section reference Retention time
----------------------------------------------------------------------------------------------------------------
1. Approved application for extension of Sec. 57.5060(c)................ Duration of extension.
time to comply with exposure limits.
2. Control plan............................ Sec. 57.5062(a)................ Duration of plan.
3. Purchase records noting sulfur content Sec. 57.5065(a)................ 1 year beyond date of purchase.
of diesel fuel.
4. Maintenance log......................... Sec. 57.5066(b)................ 1 year after date any equipment
is tagged.
5. Evidence of competence to perform Sec. 57.5066(c)................ 1 year after date maintenance
maintenance. performed.
6. Annual training provided to potentially Sec. 57.5070(b)................ 1 year beyond date training
exposed miners. completed.
7. Record of corrective action............. Sec. 57.5071(c)................ Until the citation is
terminated.
8. Sampling method used to effectively Sec. 57.5071(d)................ 5 years from sample date.
evaluate particulate concentration, and
sample results.
----------------------------------------------------------------------------------------------------------------
* * * * *
Dated: July 25, 2003.
Dave D. Lauriski,
Assistant Secretary of Labor for Mine Safety and Health.
[FR Doc. 03-20190 Filed 8-13-03; 8:45 am]
BILLING CODE 4510-43-P
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