[Federal Register: September 7, 2005 (Volume 70, Number 172)]
[Proposed Rules]
[Page 53279-53293]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr07se05-33]
[[Page 53279]]
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Part III
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
Mines; 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 Mines
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: We propose to revise the January 20, 2006 effective date of
the existing diesel particulate matter (DPM) final concentration limit
of 160 micrograms of total carbon (TC) per cubic meter of air
(160TC[mu]g/m3) in the 2001 final rule ``Diesel
Particulate Matter Exposure of Underground Metal and Nonmetal Miners,''
published in the Federal Register on January 19, 2001 (66 FR 5706). We
are considering staggered effective dates for implementation of the
final DPM limit, phased-in over a multi-year period, primarily based on
feasibility issues that have surfaced since promulgation of the 2001
final rule. We also propose to delete the existing provision that
restricts newer mines from applying for an extension of time for
meeting the final concentration limit. In addition we are seeking
specific comments and data on an appropriate conversion factor for the
final DPM limit, technological implementation issues, and the costs and
benefits of this rule. Finally, in this proposed rule, we are
interested in comments on the appropriateness of including in a final
rule a provision for medical evaluation of miners required to wear
respiratory protection and transfer of miners who have been determined
by a medical professional to be unable to wear a respirator. Specific
questions regarding these issues are discussed within the appropriate
sections in the preamble. These questions are italicized for ease of
the reader.
DATES: Public hearing dates and locations are discussed in the
SUPPLEMENTARY INFORMATION section below. If you wish to make an oral
presentation for the record, we ask that you submit your request at
least 5 days prior to the hearing dates. Comments and other appropriate
data for the record must be received by close of business on October
14, 2005.
ADDRESSES: (1) To submit comments, please include RIN: 1219-AB29 in the
subject line of the message and send them to us at either of the
following addresses.
Federal e-Rulemaking portal: Go to http://www.regulations.gov and
follow the online instructions for submitting comments.
E-mail: zzMSHA-comments@dol.gov. If you are unable to submit
comments electronically, please identify them by RIN: 1219-AB29 and
send them to us by any of the following methods.
Fax: (202) 693-9441.
Mail, hand delivery, or courier: MSHA, Office of Standards,
Regulations, and Variances, 1100 Wilson Blvd., Rm. 2350, Arlington, VA
22209-3939.
(2) We will post all comments on the Internet without change,
including any personal information they may contain. You may access the
rulemaking docket via the Internet at http://www.msha.gov/regsinfo.htm
or in person at MSHA's public reading room at 1100 Wilson Blvd., Rm.
2349, Arlington, VA.
(3) To receive an e-mail notification when we publish rulemaking
documents in the Federal Register, subscribe to our list serve at
http://www.msha.gov/subscriptions/subscribe.aspx.
FOR FURTHER INFORMATION CONTACT: For information contact Rebecca J.
Smith, Acting Director of the Office of Standards, Regulations, and
Variances, MSHA, 1100 Wilson Blvd., Arlington, Virginia 22209-3939. Ms.
Smith can be reached at (202) 693-9440.
SUPPLEMENTARY INFORMATION:
Outline of Preamble
This outline will assist the mining community in finding
information in this preamble.
I. Public Hearings
II. Rulemaking Background
A. First Partial Settlement Agreement
B. Second Partial Settlement Agreement
III. Rulemaking History
A. Advance Notice of Proposed Rulemaking (ANPRM) on the Interim
and Final Concentration Limits
B. Notice of Proposed Rulemaking (NPRM) on the Interim Limit
C. Final Rule Revising the Interim Concentration Limit
IV. Technological Feasibility
A. Introduction
B. Background
C. Remaining Technological Feasibility Issues
V. Complexity of Developing an Appropriate Conversion Factor for the
Final Concentration Limit
VI. Economic Feasibility
VII. Section 101(a)(9) of the Mine Act
VIII. Section-by-Section Analysis
A. Section 57.5060(b)
B. Effect of Eliminating Sec. 57.5060(c)(3)(i)
IX. Medical Evaluation and Transfer
X. Regulatory Impact Analysis
A. Executive Order 12866
B. Costs
C. Benefits
XI. Regulatory Flexibility Act Certification
XII. Paperwork Reduction Act
XIII. Other Regulatory Considerations
XIV. Proposed DPM Rule Text
I. Public Hearings
We will hold three public hearings on the proposed rule. The public
hearings will be begin at 9 a.m., and will be held on the following
dates and locations:
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Date Location Phone
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September 26, 2005............ Little America Hotel, (801) 363-6781
500 South Main
Street, Salt Lake
City, UT 84101.
September 28, 2005............ Clarion Hotel Sports (816) 737-0200
Complex, 9103 E.
39th Street, Kansas
City, MO 64133.
September 30, 2005............ Marriott Louisville (800) 228-9290
Downtown, 280 West
Jefferson Street,
Louisville, KY 40202.
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If you wish to make an oral presentation for the record, we ask
that you submit your request at least 5 days prior to the hearing
dates. However, you do not have to make a written request to speak. Any
unallotted time will be made available for persons making same-day
requests.
The hearings will begin with an opening statement from MSHA,
followed by an opportunity for members of the public to make oral
presentations to a panel. Speakers will speak in the order that they
sign in. 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
and 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.
[[Page 53281]]
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.
We will accept post-hearing written comments and other appropriate
data for the record from any interested party, including those not
presenting oral statements, through close of business on October 14,
2005.
II. Rulemaking Background
On January 19, 2001 we published a final rule addressing the health
hazards to underground metal and nonmetal miners from exposure to
diesel particulate matter (DPM) (66 FR 5706). The rule established new
health standards for these miners by requiring, among other things, use
of engineering and work practice controls to reduce DPM to prescribed
limits. It set an interim and final DPM concentration limit in the
underground metal and nonmetal mining environment with staggered
effective dates for implementation of the concentration limits. The
interim concentration limit of 400TC [mu]g/m3 was
to become effective on July 20, 2002. The final concentration limit of
160TC [mu]g/m3 is scheduled to become effective
January 20, 2006. In the 2001 final rule, we projected that the mining
industry would meet the final concentration limit in their mines
through the use of diesel particulate filtration devices, ventilation
changes, and the turnover of equipment and engines to less polluting
models (66 FR 5713, 5888).
Several mining trade associations and individual mine operators
challenged the final rule and the United Steelworkers of America (USWA)
intervened in the case, which is now pending in the United States Court
of Appeals for the District of Columbia Circuit. The parties agreed to
resolve their differences through settlement negotiations with us and
we delayed the effective date of certain provisions of the standard.
A. First Partial Settlement Agreement
On July 5, 2001, as a result of an agreement reached in settlement
negotiations, we published two notices in the Federal Register. One
notice (66 FR 35518) delayed the effective date of Sec. 57.5066(b)
related to tagging requirements in the maintenance standard. The second
notice (66 FR 35521) proposed a rule to make limited revisions to Sec.
57.5066(b) and added a new paragraph to Sec. 57.5067(b) ``Engines''
regarding the definition of the term ``introduced.'' We published the
final rule on February 27, 2002 (67 FR 9180).
B. Second Partial Settlement Agreement
Settlement negotiations continued on the remaining unresolved
issues in the litigation, and on July 15, 2002, the parties finalized a
written agreement (67 FR 47296, 47297). Under the agreement, the
interim concentration limit of 400TC [mu]g/m3
became effective on July 20, 2002, without further legal challenge. We
afforded mine operators one year to develop and implement good-faith
compliance strategies to meet the interim concentration limit, and we
agreed to provide compliance assistance during this one-year period. We
also agreed to propose rulemaking on several other disputed provisions
of the 2001 final rule. The legal challenge to the rule was stayed
pending completion of the additional rulemakings.
On July 20, 2003, we began full enforcement of the interim
concentration limit of 400TC [mu]g/m3. Our
enforcement policy was also based on the terms of the second partial
settlement agreement and includes the use of elemental carbon (EC) as
an analyte to ensure that a citation based on the 400 TC concentration
limit is valid and not the result of interferences (67 FR 47298). The
policy was discussed with the DPM litigants and stakeholders on July
17, 2003.
III. Rulemaking History
A. Advance Notice of Proposed Rulemaking (ANPRM) on the Interim and
Final Concentration Limits
On September 25, 2002, we published an Advance Notice of Proposed
Rulemaking (ANPRM) (67 FR 60199). We noted in the ANPRM that the scope
of the rulemaking was limited to the terms of the Second Partial
Settlement Agreement and posed a series of questions to the mining
community related to the 2001 final rule. We also stated our intent to
propose a rule to revise the surrogate for the interim and final
concentration limits and to propose a DPM control scheme similar to
that included in our longstanding hierarchy of controls scheme used in
our air quality standards (30 CFR 56/57.5001-.5006) for metal and
nonmetal mines. In addition, we stated that we would consider
technological and economic feasibility for the underground metal and
nonmetal mining industry to comply with revised interim and final DPM
limits. We determined at that time that some mine operators had begun
to implement control technology on their underground diesel-powered
equipment. Therefore, we requested relevant information on current
experiences with availability of control technology, installation of
control technology, effectiveness of control technology to reduce DPM
levels, and cost implications of compliance with the 2001 final rule.
B. Notice of Proposed Rulemaking (NPRM) on the Interim Limit
In response to our publication of the ANPRM, some commenters
recommended that we propose separate rulemakings for revising the
interim and final concentration limits to give us an opportunity to
gather further information to establish a final DPM limit, particularly
regarding feasibility. In the subsequent notice of proposed rulemaking
(NPRM) published on August 14, 2003 (68 FR 48668), we concurred with
these commenters and notified the public in the NPRM that we would
propose a separate rulemaking to amend the existing final concentration
limit of 160TC [mu]g/m3. We also requested
comments on an appropriate final DPM limit and solicited additional
information on feasibility. The proposed rule also addressed the
interim concentration limit by proposing a comparable PEL of 308 [mu]g/
m3 based on the EC surrogate and included a number of other
provisions.
C. Final Rule Revising the Interim Concentration Limit
We published the final rule revising the interim concentration
limit on June 6, 2005 (70 FR 32868). This rule changed the interim
concentration limit of 400 [mu]g/m\3\ measured by TC to a comparable
PEL of 308 [mu]g/m\3\ measured by EC. The rule requires our
longstanding hierarchy of controls that is used for our other exposure-
based health standards at metal and nonmetal mines, but retains the
prohibition on rotation of miners for compliance. Furthermore, the
rule, among other things, requires us to consider economic as well as
technological feasibility in determining if operators qualify for an
extension of time in which to meet the final DPM limit, and deletes the
requirement for a control plan.
Currently, the following provisions of the DPM standard are
effective: Sec. 57.5060(a), establishing the interim PEL of 308
micrograms of EC per cubic meter of air which is comparable in effect
to 400 micrograms of TC per cubic meter of air; Sec. 57.5060(d),
Addressing control requirements; Sec. 57.5060(e), Prohibiting rotation
of miners for compliance with the DPM standard; Sec. 57.5061,
Compliance determinations; Sec. 57.5065, Fueling practices; Sec.
57.5066,
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Maintenance standards; Sec. 57.5067, Engines; Sec. 57.5070, Miner
training; Sec. 57.5071, Exposure monitoring; and, Sec. 57.5075,
Diesel particulate records.
IV. Technological Feasibility
A. Introduction
When we promulgated the 2001 final rule, we determined that control
technologies would be available by January 20, 2006 to reduce DPM
concentrations to 160TC [mu]g/m\3\ micrograms in all types
of underground metal and nonmetal mines. In the 2001 final rule, we
established a new compliance scheme for these mine operators to
implement that was distinguishable from that of our other exposure-
based health standards by requiring that miners' exposures be reduced
to a full-shift equivalent environmental or concentration limit where
miners work or travel. Historically, our metal and nonmetal exposure-
based health standards have been based on a miner's full-shift personal
exposure and required that mine operators reduce miners' exposures to
hazardous chemical substances by establishing a hierarchy of controls
utilizing feasible engineering and administrative controls supplemented
by respiratory protection, if necessary. Since, we were regulating DPM
for the first time we needed a tool to help us to determine whether the
mining industry was capable of meeting the interim and final
concentration limits of the 2001 final rule using a combination of
engineering and work practice controls. We also needed a compliance
assistance tool to help mine operators with selection of feasible
controls from technology unfamiliar to the mining industry.
Consequently, we developed the Estimator.
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. This model is in
the form of a spreadsheet template that permits instant display of
outcomes as inputs are altered. Depending on the amount and type of
equipment an operator uses, mining companies could use the Estimator to
evaluate the effectiveness of these controls prior to purchasing and
installing such controls. We encouraged mine operators to use this tool
to assist them in making their decisions regarding the appropriate
controls for their mines in meeting the 2001 concentration limits.
In the preamble to the 2001 final rule, we included data from our
studies where we evaluated emissions generated by diesel powered
equipment in several diverse underground mining operations which
included an underground limestone mine, an underground salt mine, and
an underground gold mine. In each mine, we concluded that the necessary
combination of controls was available to reduce DPM concentrations well
below the final concentration limit. Based on these studies, we
concluded that engineering and work practice controls were available to
reduce DPM concentrations in all underground metal and nonmetal mines
to the required limits. We also distributed to the mining community our
publication of ``Practical Ways to Control Exposure to Diesel Exhaust
in Mining--a Toolbox'' which addresses various categories of available
DPM controls. These categories of controls include use of low emission
engines, low sulfur fuel, aftertreatment devices, ventilation, enclosed
cabs, engine maintenance, work practices and training, fleet
management, and respiratory protective equipment (66 FR 5712-13).
Furthermore, we also examined information regarding types of engines
and equipment found in underground metal and nonmetal mines along with
their various ventilation systems and concluded that the 2001 final
rule was technologically feasible for the mining industry (66 FR 5889).
We also concluded that the 2001 final rule was economically
feasible but recognized the broad impact of the rule on the underground
metal and nonmetal sector of the mining industry. We estimated that the
annual cost of the 2001 final rule for these mines would be $25.1
million. The cost for an average underground metal and nonmetal mine
was projected to be approximately $128,000 annually primarily for
investment in equipment to meet the interim and final concentration
limits. In reaching our cost estimates, we anticipated that the interim
concentration limit would be met primarily with the use of diesel
particulate filters (DPFs), environmental cabs, and ventilation; and
the final concentration limit would be met with expanded use of DPFs,
ventilation, and turnover in equipment to less polluting models (66 FR
5713, 5888).
We included a provision in the 2001 final rule to allow an
additional two years for mines experiencing difficulty in reducing DPM
levels to the final concentration limit due to technological
constraints (66 FR 5861). The June 6, 2005, final rule on the interim
limit subsequently revised the extension requirement to provide one
year, renewable, extensions to comply with the final limit, based on
economic or technological infeasibility, but continues to prohibit
newer mines from applying for extensions (70 FR 32966).
Following promulgation of the 2001 final rule, we agreed to engage
in a joint MSHA/industry 31-Mine Study to, among other things, assess
the technological and economic feasibility of underground metal and
nonmetal mine operators to achieve compliance with the interim and
final DPM concentration limits. Feasibility at each of the 31 mines was
determined using the Estimator. 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. On January 6, 2003, we
issued our final report entitled, ``MSHA'S Report on Data Collected
during a Joint MSHA/Industry Study of DPM Levels in Underground Metal
and Nonmetal Mines.'' With regard to feasibility of compliance with
both the interim and final concentration limits, we concluded in the
study that it may be both technologically and economically feasible for
metal and nonmetal underground mines to comply with the 2001 rule. At
that time, however, we acknowledged our limited in-mine documentation
on implementation of DPM control technology with issues such as
retrofitting and regeneration of filters. Consequently, we committed to
continue to consult with the National Institute for Occupational Safety
and Health, industry and labor representatives on the availability of
practical mine worthy filter technology. NIOSH peer reviewed our final
report of the 31-Mine Study (70 FR 32870-73).
Furthermore, by letter to MSHA dated June 25, 2003, NIOSH stated
that:
Operators will need to make informed decisions regarding filter
selection, retrofitting, engine and equipment deployment, operation,
and maintenance, and specifically work through issues such as in-use
efficiencies, secondary emissions, engine backpressure, DPF
regeneration, DPF reliability and durability. NIOSH is of the
opinion that these issues can be solved if the informed decisions
mentioned above are made. (70 FR 32923)
In the 2005 rulemaking on the interim limit, we revised our
approach to reducing DPM levels by establishing our longstanding
hierarchy of controls used for regulating our other exposure-based
health standards at metal and nonmetal mines. Also, we changed the
concentration limit to a permissible exposure limit whereby we measure
a miner's personal exposure. The Estimator became less significant from
our perspective in demonstrating feasibility since the 2005 rulemaking
[[Page 53283]]
record included more extensive evidence on the ability of the mining
industry to meet the interim limit in 2005. Specifically, our
rulemaking record included: our final report on the 31-Mine Study;
NIOSH's peer review of the 31-Mine Study; results from our baseline
sampling at mines covered under the DPM standard; results of our
comprehensive compliance assistance work at mining operations with
implementation issues affecting feasibility; NIOSH's conclusions on the
performance of the SKC sampler and the availability of technology for
control of DPM; NIOSH's Diesel Emissions Workshops in 2003 in
Cincinnati and Salt Lake City; the Filter Selection Guide posted on the
MSHA and NIOSH web sites; MSHA's final report on DPM filter efficiency;
NIOSH's report titled, ``Review of Technology Available to the
Underground Mining Industry for Control of Diesel Emissions'; and, the
NIOSH Phase I Isozone study titled, ``The Effectiveness of Selected
Technologies in Controlling Diesel Emissions in an Underground Mine--
Isolated Zone Study at Stillwater Mining Company's Nye Mine,'' all of
which were developed following promulgation of the 2001 DPM final rule
(70 FR 32916).
To attain the interim DPM limit, mine operators are required to
install, use, and maintain engineering and administrative controls to
the extent feasible. When these controls do not reduce a miner's
exposure to the DPM limit, controls are infeasible, or controls do not
produce significant reductions in DPM exposures, operators must
continue to use all feasible engineering and administrative controls
and supplement them with respiratory protection. When respiratory
protection is required under the final standard, mine operators must
establish a respiratory protection program that meets the specified
requirements. At this time, we believe that this compliance approach
coupled with the time-frame for complying with the phased-in limits
provides mine operators with maximum flexibility in compliance. We
believe that this current compliance approach which incorporates the
industrial hygiene concept of a hierarchy of controls scheme for
implementing DPM controls would result in feasibility of compliance
with each of the phased-in limits contained in this proposal. However,
we continue to acknowledge that compliance difficulties may be
encountered at some mines due to implementation issues and the cost of
purchasing and installing certain types of controls.
1. MSHA's 2001 Assumptions Regarding Compliance With the Final
Concentration Limit
The assumptions that we used in 2001 in support of our cost
estimates included:
(a) Fifty percent of the fleet will have new engines (these new
engines do not impact cost of the rule) * * * Moreover, due to EPA
[Environmental Protection Agency] regulations which will limit DPM
emissions from engines used in surface construction, surface mining,
and over-the-road trucks (the major markets for heavy duty diesel
engines), the market for low tech ``dirtier'' engines will dry up *
* * (b) one hundred percent of the production equipment and about
fifty percent of the support equipment will be equipped with
filters; (c) about thirty percent of all equipment will need to be
equipped with environmentally controlled cabs; (d) twenty three
percent of the mines would need new ventilation systems (fans and
motors); (e) forty percent of the mines will need new motors on
these fans; and (f) thirty two percent of the mines will need major
ventilation upgrades (66 FR 5889-90).
Furthermore, we concluded that it would not be feasible to require
this sector, as a whole, to lower DPM concentrations further, or to
implement the required controls more swiftly (66 FR 5888).
2. Reasons Why the 2001 Assumptions Are Now Being Questioned.
During the 4\1/2\ years since the 2001 final rule was promulgated,
the mining industry and MSHA have gained considerable experience with
the implementation, use, and cost of DPM control technology. Miners'
DPM exposures have also have declined significantly from a mean of
808DPM [mu]g/m\3\ (646TC [mu]g/m\3\ [mu]g/m\3\
equivalent) prior to the implementation of the standard, to a mean of
233TC [mu]g/m\3\ based on current enforcement sampling. The
industry, however, is encountering economic and technological
feasibility issues with DPM controls as they strive to reduce levels
below the interim limit. When we established the 2001 final limit, we
were expecting some mine operators to encounter difficulties
implementing control technology because the rule was technology
forcing. We projected that by this time, practical and effective filter
technology would be available that could be retrofitted onto most
underground diesel powered equipment. However, as a result of our
compliance assistance efforts and through our enforcement of the
interim limit, we have become aware that this assumption may not be
valid. The applications, engineering and related technological
implementation issues that we believed would have been easily solved by
now are more complex and extensive than previously thought.
Although DPF systems have been proven to be highly effective in
reducing elemental carbon, mines are currently experiencing problems
with selection and implementation of DPF systems for complying with the
interim limit. Since the final limit will require mines to install more
DPF systems, these selection and implementation problems will extend
over a large portion of the mining industry. At this time we believe
that solutions to the problems of selection and implementation have not
proceeded as quickly as anticipated since promulgation of the 2001
final rule and many mines will not be able to achieve the final limit
by January 20, 2006. Some of the implementation and operational
difficulties encountered with the controls are discussed in the
sections below.
We seek additional information regarding technological difficulties
and whether they will increase the cost to comply with the final
concentration limit above that estimated in the 2001 final rule. We are
particularly interested in whether mine operators have attempted to
institute DPF systems that are impractical or have failed to work for
their mining operations. We wish to know what types and sizes of DPFs
have been evaluated, what types of equipment have been fitted with
DPFs, what types and horsepower of engines were installed on the
equipment, details concerning monitoring of equipment exhaust
temperatures prior to specifying a DPF for a given application, whether
DPF installations include a provision for backpressure monitoring, DPF
maintenance intervals, DPF life, the results of any DPF failure mode
analysis, DPM reductions obtained, and any other data related to in-
mine experiences with DPFs on underground metal and nonmetal mining
equipment.
We believe that wider use of alternative fuels and filter
technology can make the 160TC [mu]g/m\3\ final limit
feasible if a staggered phase-in approach is adopted. By lowering the
exposure limit in intervals over five years beginning in January 2007,
market forces should have sufficient time and incentive to adjust to
the new standard. Specifically, a reliable alternative fuel
distribution system should induce mine operators to adopt this
relatively low-cost method to achieve compliance. The development and
distribution of alternative fuels is also encouraged by existing tax
credits. We believe that regional distribution networks are
[[Page 53284]]
beginning to emerge. We seek data on alternative fuel distribution
systems.
Retrofit options for self-cleaning filters should increase as the
filter manufacturers become assured of a reliable market for the
devices. Use of newer equipment with cleaner engines will also increase
as older equipment is retired from service. We anticipate that this
staggered approach will provide the needed time to resolve these
logistical and operational issues, and consequently, may not increase
our 2001 projection of the cost of compliance with the rule. During
this phase-in, we will continue to work with the Diesel Partnership
(discussed below) and the mining industry to address the DPF selection
and implementation problems and identify effective solutions for the
diverse metal and nonmetal mining environment.
Additionally, we request comments on the percentage of diesel
equipment, by mine size, in metal and nonmetal mines that currently
have newer, low DPM emitting engines such as EPA Tier I and Tier 2
compliant engines. Our 2001 cost estimates were based, in part, on the
assumption that by the effective date of the final limit, 50% of the
diesel equipment fleet would have new engines (66 FR 5889). We are
interested in whether our 2001 assumption was accurate. If the
percentage is lower than originally estimated, it may require the
industry to rely even more heavily on filters and other types of
controls at added costs. Relying on DPFs to be installed on older,
higher DPM emitting engines may also introduce additional
implementation issues since DPF manufacturers normally do not recommend
adding DPFs to older engines. Although we recognize various types of
controls that mine operators could use to reduce miner exposure to DPM,
we believe that turnover in equipment to less polluting models and the
use of DPFs would be the primary method of achieving compliance with
the final DPM limit.
We also recognize promising advances in alternative fuel technology
since the 2001 final rule was promulgated. These fuels can be extremely
effective in reducing DPM emissions. Additionally, the fuels would be
in tune with recent U.S. initiatives towards greater energy
independence. On October 22, 2004, President Bush signed into law a 50-
cent-per-gallon tax credit for producers of bio-diesel. He also
extended federal tax credits for ethanol through 2007 as part of H.R.
4520, also known as the American Jobs Creation Act of 2004 (Pub. L.
108-357).
Currently, however, logistical problems exist with the distribution
of these fuels to remote mining areas, and the effect of these fuels on
power output and operation at high altitude needs to be addressed more
fully.
Although MSHA, industry, and the Diesel Partnership are actively
working to address these concerns, additional time may be needed to
find effective solutions for the implementation of DPM controls.
B. Background
1. Diversity of Underground Mines Affected By the Final DPM
Concentration Limit
The metal and nonmetal mining industry has 177 underground mines
that use numerous pieces of diesel powered equipment, widely
distributed throughout each mining operation. These mines employ an
array of mining technologies to produce commodities including metals
such as lead, zinc, platinum, gold, silver, etc. Also, there are
different types of nonmetal mines that produce stone products such as
limestone, dolomite, sandstone, and marble. Other underground nonmetal
mines produce clay, potash, trona, soda ash, and salt. Not only do
these mines vary in the commodities that they produce, but they also
use different mine designs and mining techniques such as room and
pillar mining and stope mining. Some of these mines are large, complex
multilevel mines, while others are small adit-type mines. Ventilation
levels in these mines also vary widely. Many limestone mines have only
natural ventilation with variable air movement, whereas trona mines
have high ventilation rates to dilute and remove methane gas released
in the mining process. There are also deep metal mines with multiple
levels that have far less ventilation than that found in underground
trona mines. Furthermore, many metal and nonmetal mines are located in
remote areas of the country, at high altitudes, or are subject to
extremely hot or cold environments. Considering these factors as a
whole, we have found that there is no single solution to control
technology that would be effective for all metal and nonmetal mines in
significantly reducing current DPM levels to or below the final DPM
concentration limit of 160TC micrograms.
2. Work of the M/NM Diesel Partnership (the Partnership)
Since promulgation of the January 2001 final rule, we have worked
with a Partnership that is composed of representatives from the
National Institute for Occupational Safety and Health (NIOSH), industry
trade associations, and organized labor. We are not a member of the
Partnership because of our ongoing DPM rulemaking activities. The
primary purpose of the Partnership is to identify technologically and
economically feasible controls using existing and available technology
that can be retrofitted onto existing diesel powered equipment in
underground metal and nonmetal mines to reduce diesel particulate
matter emissions to, or below, our interim and final limits.
The Partnership has been actively involved with NIOSH in its work
on diesel particulate control technology including its isolated zone
studies at the Stillwater Mine in Montana. NIOSH has published the
following reports of its work with the Partnership: ``The Effectiveness
of Selected Technologies in Controlling Diesel Emissions in an
Underground Mine--Isolated Zone Study at Stillwater Mining Company's
Nye Mine (Phase I Study);'' ``An Evaluation of the Effects of Diesel
Particulate Filter Systems on Air Quality and Personal Exposure of
Miners at Stillwater Mining Case Study: Production Zone (Phase II
Study);'' and, ``The Effectiveness of Reformulated Fuels and
Aftertreatment Technologies in Controlling Diesel Emissions (Phase
III--A Study in an Isolated Zone at Stillwater Mining Company's Nye
Mine August 31-September 11, 2004).'' NIOSH stated in its conclusion to
the Phase III study that:
This study did not address the important critical path of
economic and technical aspects relating to implementation of the
studied technologies into underground mines. The successful
implementation of control technologies is predicated on addressing
issues which are relatively unique to each mine and even to
individual applications within a given mine. Most of these technical
and operational issues could be investigated through a series of
long-term field studies where control technologies would be wisely
selected and optimized for the applications, performance of the
technologies would be continuously monitored and the effects of the
controls on concentrations of diesel pollutants in the mine air
would be periodically assessed. The findings of such studies would
allow operators to make informed decisions regarding the selection,
optimization and implementation of control technologies for its
applications and maximize the benefits of using those technologies.
It is recommended that these studies be designed and undertaken
under the leadership of the Metal/Nonmetal Diesel Partnership.
On-going NIOSH diesel research related to the Partnership includes
a contract that the NIOSH Pittsburgh Research Laboratory issued to
Johnson
[[Page 53285]]
Matthey Catalyst to develop a system to control nitrogen dioxide
(NO2) emissions from diesel-powered underground mining
vehicles equipped with the Johnson Matthey's Continuously Regenerating
Trap (CRT[supreg]) system. This system promotes regeneration at lower
temperatures and is widely used in urban bus applications. If the
results of laboratory evaluations show that a system is suitable for
use in underground mining, NIOSH would continue studying this control
technology with a long-term field evaluation in an underground mine.
C. Remaining Technological Feasibility Issues
In January 2001, we concluded that technology existed to sample
accurately for DPM with a TC method and to bring DPM levels to the 160
TC level by January 2006 (66 FR at 5889). We further concluded that if
any particular mine found unforeseen technological barriers to meeting
the January 2006 deadline, it could apply for an extension of up to two
additional years to comply with the 160 limit (66 FR at 5889). Our
discussion of technological feasibility in support of the interim PEL
of 308EC [mu]g/m\3\ in the June 6, 2005 final rule concluded
that it was technologically feasible to reduce underground miners'
exposures to the interim PEL by using available engineering control
technology and various administrative control methods. In fact, our
testing at Kennecott Minerals Green's Creek Mine showed that ceramic
diesel particulate filters (DPFs) were capable of reducing diesel
exposures by 95%. However, we acknowledged that compliance difficulties
may be encountered at some mines due to implementation issues and the
cost of purchasing and installing certain types of controls.
Specifically, implementation issues may adversely affect the
feasibility of using DPFs to reduce exposures despite the results
reported in NIOSH's Phase I Isozone Study.
Our experience since January 2001 has raised questions on
technological feasibility for the mining industry as a whole, rather
than for a small number of individual mines, to meet the 160 TC
concentration limit by January 20, 2006. When we conducted our baseline
sampling in 2002 and 2003, we found that over 75% of the underground
mines covered by the 2001 final rule have levels that would exceed the
final concentration limit of 160TC micrograms. Our current
enforcement data indicate that approximately 65% of the underground
mines covered by the 2001 final rule have levels that would exceed the
final concentration limit. Although exposures have decreased with
implementation of controls and enforcement of the interim concentration
limit, we have tentatively concluded that the 160TC
microgram final concentration limit presents a significant challenge to
a substantial number of underground mine operators and compliance may
not be feasible by January 2006. That conclusion is supported by our
current enforcement sampling results that indicate that many mining
operations have exposures above the 160TC concentration
limit, and availability of effective control technology that will
reduce exposures to the final limit is speculative at this time.
Moreover, comments from industry trade associations and individual mine
operators in the post-January 2001 rulemakings recommended that we
repeal the 160 limit as technologically infeasible. Organized labor, on
the other hand, has recommended that a limit below 160 is
technologically feasible. We request comments on whether compliance is
technologically feasible by January 2006 and the appropriateness of a
multi-year phase-in of the final limit. We also request comments and
data on when the technology will be feasible. Specific technological
implementation issues are discussed in more detail in the following
subsections C.1 through C.4.
We also request comments on whether compliance difficulties may
lead to another problem by requiring a large number of miners to wear
respirators until feasible controls are fully implemented. We have
never had a standard that resulted in a significant percentage of the
workforce being required to wear respiratory protection, and we are
concerned about the impact on worker acceptance of the rule and about
mine operators' ability to remain productive. We are interested in
public comment on how many miners would need to wear respirators to
comply with the 2001 final limit and proposed multi-year phase-in of
the final limit, and whether in each case they would need to wear
respirators for their entire work shift, whether this amount of
respirator usage is practical, and any other comments or observations
concerning this issue.
1. Implementation of Available DPFs
We continue to project that many mine operators will have to use
DPFs to reduce DPM levels to the final concentration limit. The mining
industry maintains that while some operators are using DPFs to control
miners' exposures to the interim PEL, it is infeasible for them to
further reduce miners' exposures through expanded use of DPFs.
While passive DPF regeneration systems are preferred over active
regeneration systems, many pieces of mining equipment do not have duty
cycles that will consistently support passive regeneration. Passive
regeneration is the process where the exhaust gas temperature produced
by the engine is sufficient to burn off the collected DPM on the DPF.
Passive regeneration is normally preferred because a DPF can be
installed on a machine, and the operator does not have to be concerned
with removing the DPF on a routine schedule that may occur at the end
of every shift. However, passive regeneration does require the machine
operator to monitor the engine's exhaust gas backpressure. As the DPF
loads up with DPM, the inability of the exhaust gas to burn off the DPM
allows the backpressure to increase. Increasing the backpressure above
the manufacturer's specifications can cause engine and DPF damage. We
request information on the number of currently installed passive
regeneration DPF filters. Also, we are interested in the methods used
by the industry to match a passive regeneration DPF to a machine.
However, we are aware that two identical machines operating in two
different mines may not both be able to use passive regeneration. We
would be interested in comments about practical experience with these
implementation issues.
If passive regeneration is infeasible, active regeneration is an
alternative. Active regeneration depends on an external heat source for
burning off the DPM. Mine operators have informed us that some mining
operations cannot utilize active regeneration due to physical size of
filters, machine down time, or the cost associated with underground
regeneration stations required for DPF regeneration. We request that
commenters submit information from the mines that are utilizing active
regeneration including data regarding the benefits and the
practicability of active regenerating filters.
Engine emissions and exhaust flows also affect the size of the DPF
that needs to be installed. Both of these factors can affect both
passive and active regeneration. If the DPF is undersized for a
particular application due to high DPM emissions or high exhaust flows,
a passive or active DPF system may not make it through the entire shift
before it must be taken out of service for regeneration because of the
high backpressure.
[[Page 53286]]
While some of the mining industry has made improvements by
replacing older engines with newer engines in order to reduce DPM
emissions, we believe this has occurred mostly for the larger
horsepower engines, greater than 150 hp. Smaller engines normally found
in the support equipment have not had DPM reductions equivalent to the
larger engines. Since we estimated that 50% of the support equipment
would probably need DPFs for compliance with the final limit (66 FR
5889-90), the higher DPM emissions from the engines used in support
equipment can further complicate the impact on compliance. The mining
industry has stated that it needs additional time to further evaluate
the proper sizing of DPF systems for both passive and active
regeneration.
We seek further comment regarding these technological
implementation issues as they affect feasibility of compliance with the
final concentration limit including the practicality of available DPM
control technology. We request that the mining community specifically
address issues surrounding off-board regeneration: back pressure build
up; frequency of the necessity to clean DPFs; the difficulty of
placement of regeneration stations; and information on the extent to
which diesel powered equipment accommodates a retrofit of the DPF.
2. Benefits of On-Board Regeneration
a. ArvinMeritor[supreg] System. The ArvinMeritor[supreg] system,
which utilizes active regeneration of the DPF, offers great potential
for underground mines in further reducing DPM exposures. The
ArvinMeritor[supreg] system utilizes an on-board fuel burner system to
regenerate DPFs. This system actively regenerates the filter media
during normal equipment operations by causing the fuel to ignite the
burner and thereby increase the exhaust temperature in the filter
system. Consequently, this system does not require the host vehicle to
travel to a regeneration station to regenerate the DPF. The condition
of the DPF is monitored via sensors. While this product was
successfully evaluated at Stillwater's Nye Mine, we have recently
learned that the manufacturer has decided to concentrate on working
with Original Equipment Manufacturers (OEMs) where they would be
selling 50 units or more to one customer rather than selling one or two
units per customer.
b. Johnson Matthey's CRT[supreg] System for DPM reduction (Johnson
Matthey). As stated above, passive regeneration works by using the
exhaust gas generated by the engine to burn the DPM. Normally, DPF
manufacturers utilize catalyst technology to lower the temperature
needed for successful passive regeneration. By lowering the exhaust gas
temperature needed for passive regeneration, a broader range of
machines will have the necessary duty cycle to generate the exhaust gas
temperature needed to burn the DPM. However, when a platinum coating is
used as the catalyst, it can also increase the nitrogen dioxide
(NO2) emissions from the engine exhaust. In mines with low
ventilation rates, the increased NO2 emissions can also
result in increased NO2 exposures to potentially dangerous
levels for miners. We discuss this issue in the final rule on the
interim PEL (70 FR 32924-26). Therefore, other methods for passive
regeneration are being developed to resolve these issues.
In 2004, the NIOSH Pittsburgh Research Laboratory issued a contract
to Johnson Matthey to develop a system that can regenerate at lower
exhaust gas temperatures and control NO2 emissions. The
system is based on Johnson Matthey's CRT[supreg] system and promotes
regeneration at lower temperatures. Such DPFs are widely used in urban
bus applications and are capable of passively regenerating DPFs at the
temperatures commonly seen in the exhausts of underground mining
equipment (above 250 [deg]C for at least 40% of the operation time).
The laboratory evaluation of the systems is being executed under
NIOSH contract by the Center for Diesel Research (CDR) at the
University of Minnesota. The objective is to examine performance and
suitability of the systems relative to heavy-duty diesel engines in
underground mining applications, with specific focus on the
effectiveness of controlling NO2. If the results of
laboratory evaluations show that the system is suitable for use in
underground applications, NIOSH would continue to study this promising
control with a long-term field evaluation in an underground mine
environment. We request comments from the mining community regarding
the foreseeable utility of these and other new control technologies for
reducing DPM levels in underground metal and nonmetal mines.
3. Operators' Limited Access to Alternative Fuels and Ultra Low-Sulphur
Fuels
During our compliance assistance efforts, we observed mines with
several applications of alternative fuels, including water emulsion
fuels and bio-diesel fuels both of which are EPA approved fuels. We
subsequently tested these alternative fuels to determine if they could
decrease tailpipe DPM emissions. In each application the change to an
alternative fuel had a positive impact on reducing engine emissions and
miners' exposures to DPM. In some cases, reductions of 50 to 80+
percent were measured. While we found notable benefits, the use of
alternative fuels can also cause equipment operation issues for mine
operators. These operational issues have included initial clogging of
the fuel filters when bio-diesel is used, reduction of horsepower with
the use of water emulsion fuels, and management of proper fueling of
the correct fuel into specific machines. While these operational issues
could be overcome, each mine has to work through implementation issues
on a case-by-case basis.
The most common problem with alternative fuels is lack of
geographic proximity of most mines to a fuel distributor. Fuel
distribution centers tend to be near large cities. As a result,
alternative fuels need to be transported to mine sites, in some cases
significantly increasing costs. Fuel manufacturers are building
distribution centers near mining areas to reduce the transportation
costs, but these centers will take some additional time to complete.
Limited distribution is also a feasibility issue for metal and nonmetal
mine operators who seek to obtain ultra low sulfur fuel. However, as
discussed elsewhere in this preamble, the commercial availability of
ultra low sulfur fuel will increase during 2006 and beyond when on-
highway vehicles in the United States will be required by the EPA to
use only this type of diesel fuel.
a. Water Emulsion Fuels. Water emulsion fuels, such as PuriNox, are
blends of diesel fuels and water. The water is held in suspension with
a surfactant. The water in the fuel reduces the engine combustion
temperature resulting in reduced NO2 and reduced DPM
emissions. However, the added water also reduces the engine's
horsepower. While the per gallon price of the water emulsion fuel is
the same as standard fuel, we are aware of increases in engine
consumption of these fuels by as much as 15 percent. However, continued
increased use in mines is currently limited due to lack of fuel
availability in most mining regions. Manufacturers of this fuel must
install centralized blender facilities in order to make the fuel more
available and economically feasible for use by the metal and nonmetal
mining industry.
Some fuel system issues have also been observed with some engines
using water emulsion fuels. One issue appears
[[Page 53287]]
to be with the use of very efficient water separators used on engine
fuel systems to remove water from the fuel lines. A very efficient
water separator will actually remove the water from the emulsion, thus
affecting the engine's performance. An engine manufacturer that has
experienced this with its engines has recommended replacing the more
efficient water separator with a less efficient one.
Another issue identified by some mine operators is that some small
machines cannot run, or run poorly, on this fuel. We are not aware of
any testing that has been done to prove or disprove this. This may or
may not be due to less complex fuel systems that cannot handle a change
in fuel properties. We request any information that would help a mine
operator determine if certain machines in a fleet cannot run
efficiently on this type of fuel.
Since water emulsion fuels have been associated with horsepower
loss, mines will have to determine through their own in-mine test if
their machines can continue to operate efficiently even with the power
loss. Some situations where the power loss could affect a machine's
productivity occur at multilevel underground mines at high altitudes.
Also, mines that require the use of permissible engines with pre-
chamber combustion, such as the metal and nonmetal gassy mines, may
need to determine any additional effects on these types of engines.
These mines may need additional time to assess the impact of the
elevation and grade on power loss. We request comments on the mining
industry's experience with using water emulsion fuels to reduce DPM
exposures.
b. Bio-Diesel Fuels. While bio-diesel fuels are more readily
available than water emulsion fuels, there has not been a consistent
supply or standard cost of the fuel. Both costs and demand for these
fuels in the mining industry have been related primarily to tax credits
available for using the fuel. With current tax credits, bio-diesel can
be an attractive fuel alternative for the mining industry. However, we
have observed maintenance issues with application of bio-diesel fuels
similar to those associated with water emulsion fuels. Particularly,
bio-diesel functions as a solvent and cleans the fuel system. This
results in increased clogging and replacement of fuel filters. It may
take the mining industry some additional time to assess the impact of
the increased maintenance on a mining operation.
The other issue related to the use of bio-diesel fuel is the
percent of soy oil in the mixture. While any blend is available, B20 is
a 20 percent blend, and B50 is a 50 percent blend, etc., we note that
significant DPM reductions are not realized unless the bio-diesel blend
exceeds 20 percent. We request comments on the mining industry's
experience with using bio-diesel fuels to reduce DPM exposures.
4. Installation of Environmental Cabs
Environmental cabs are a proven means to reduce worker exposure to
DPM. While much of the construction-type equipment used in underground
stone mines comes equipped with environmental cabs, the cabs on
specialty mining equipment used in underground hard rock mining are
less common, particularly in mines with narrow drifts or low seam
heights. As mine operators realize the benefits of cabs, more and more
pieces of equipment are being purchased or retrofitted with
environmental cabs. These cabs provide protection for workers not only
from diesel particulate but also from noise and dust.
Many mines have begun a retrofit program, but may require
additional time to design and retrofit specialty mining equipment with
environmental cabs. We request comments on the mining industry's
experience with using environmental cabs to reduce DPM exposures.
V. Complexity of Developing an Appropriate Conversion Factor for the
Final Concentration Limit
The June 6, 2005 rule uses a 1.3 conversion factor to convert the
interim PEL of 400TC [mu]g/m3 to 308EC
[mu]g/m3, because EC comprises only a fraction of TC. We
used a factor of 1.3, to be divided into 400TC [mu]g/
m3, to produce a reasonable estimate of TC without
interferences. The EC interim limit is based on the median TC to EC
(TC/EC) ratio of 1.3 that was observed for valid samples in the 31-Mine
Study and agreed to in the second partial DPM settlement agreement (70
FR 32944). Enforcement sample results to date have also shown that for
the 400TC [mu]g/m3 interim limit, 1.3 is the most
appropriate conversion factor.
However, we believe at this time that the 1.3 conversion factor may
not be appropriate to convert the final phased-in TC limits to EC
because of the variety of DPM controls being adopted by mine operators
since the 31-Mine Study. Depending on the types of DPM controls being
installed at the mines, a new conversion factor for EC may be needed.
Clean engines have more of an impact on reducing OC levels. Alternative
fuels, ventilation, and work practices seem to lower EC and TC at
similar rates, while DPF and environmental cabs appear to be more
effective in reducing EC levels. The actual TC to EC ratio could vary
from mine to mine, and even from one section in a mine to another,
based on the mix of controls at a mine. We are seeking to maintain the
level of protection for miners provided by the final limit promulgated
by the 2001 final rule, pursuant to Section 101(a)(9) of the Mine Act.
When considering the feasibility of compliance and sampling
constraints, we believe that the conversion factor from TC to EC for
the phased-in final limits should take into account the OC and EC
ratios so that the OC and EC components together would be equivalent to
a TC concentration. We are working with NIOSH to develop an appropriate
conversion factor for converting the TC limits of this rulemaking to EC
limits. Information provided by NIOSH indicated that the ratio of TC to
EC in the 31-Mine Study is 1.25 to 1.67 (70 FR 32944). NIOSH's report
on the Phase I study conducted in May, 2003, shows that the EC
reduction in the isolated zone with one DPF system was 88% and that two
other systems gave greater than 96% EC reductions when the measured
concentrations were normalized by ventilation rate. In the final report
of the Phase II study, NIOSH indicated that higher EC reductions were
observed in the field than were obtained in the laboratory for whole
diesel particulate. The results of these studies, as well as other mine
studies NIOSH has conducted, help inform us of the EC to TC ratio at
different DPM concentrations. Measuring only the EC component ensures
that only diesel particulate material is being measured. However, there
are no established relationships between the concentration of EC and
total DPM under various operating conditions. We welcome comments
regarding the types of data we should request from NIOSH to assist us
in developing an appropriate conversion factor for converting the TC
limits of this proposed rule to EC limits.
We will initiate a separate rulemaking to determine what the
correct TC to EC conversion factor will be for the phased-in final
limits. In the meantime, we are interested in receiving comments on
whether the record supports an EC PEL without regard to any conversion
factor, the appropriate conversion factor if one is used, and any other
scientific approaches for converting the existing TC limit to an
appropriate EC limit. However, if a rulemaking to establish a
conversion factor is not complete before January 20, 2007, we are
considering
[[Page 53288]]
using the current 1.3 conversion factor that we used to establish the
interim DPM PEL of 308 EC micrograms to convert the phased-in final DPM
TC limits to EC equivalents. As we did with the interim TC limit
pursuant to the July 2002 settlement, we would use the EC equivalents
as a check to validate that an overexposure is not the result of
interferences. We are interested in receiving comments on this approach
to enforcement of the 2007 PEL, assuming the conversion factor
rulemaking is not completed before January 20, 2007.
VI. Economic Feasibility
In January 2001, we estimated that yearly cost of the final rule
would be about 0.67% of yearly industry revenue, which was less than
the 1% ``screen'' of costs relative to revenues that we use as a
presumptive benchmark of economic feasibility (66 FR 5889). In this
rulemaking to consider a phased-in approach to the final concentration
limit of 160 TC micrograms, we intend to use the entire rulemaking
record supporting the 2001 final rule and the new information gathered
during the recent rulemaking to promulgate the new interim PEL. Our
data in the rulemaking record established that few underground mines
would experience severe economic hardship from enforcement of the
interim PEL. Our subsequent enforcement data have confirmed that the
interim PEL is economically feasible. In order to gain a more thorough
rulemaking record, particularly in light of recent technological
developments, we request comments on the economic feasibility of the
final concentration limit of 160 TC micrograms and implications of the
proposed phase-in approach on the economic feasibility.
VII. Section 101(a)(9) of the Mine Act
Section 101(a)(9) of the Mine Act provides that: ``No mandatory
health or safety standard promulgated under this title shall reduce the
protection afforded miners by an existing mandatory health or safety
standard.'' We interpret 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. The U.S. Court of Appeals for the D.C. Circuit approved
such a ``net effects'' application of Section 101(a)(9). Int'l Union,
UMWA v. Federal Mine Safety and Health Admin., 407 F. 3d 1250, 1256-57
(DC Cir. 2005).
We have tentatively concluded at this point that this proposed
phase-in period of the effective date of existing Sec. 57.5060(b) of
the 2001 final rule establishing a final DPM concentration limit of
160TC [mu]g/m3 will not reduce miner protection.
We are concerned that the final concentration limit may be infeasible
for the mining industry in January 2006. Feasibility issues with
respect to operator compliance are discussed above. Also, an additional
concern is whether an effective sampling strategy exists to enforce the
final TC concentration limits with TC as the surrogate. Evidence in the
rulemaking record after January 2001 suggests that, in many cases,
there is no practical sampling strategy that would adequately remove
organic carbon interferences that occur when TC is used as the
surrogate. Furthermore, the DPM settlement agreement does not address
appropriate enforcement procedures for the final concentration limit.
We also believe at this time that the 1.3 conversion factor used for
the final interim limit may not be appropriate for substantially lower
limits, such as the final TC concentration limit of 160TC
[mu]g/m3. Thus, we have concluded at this time that it is
questionable whether the final concentration limit of 160TC
[mu]g/m3 would provide any more protection for miners than
the 308EC [mu]g/m3 interim limit. We have the
burden of proof to confirm that an overexposure to DPM actually
occurred and the sample result is not due to interferences. If we were
to enforce the final DPM concentration limit of 160TC [mu]g/
m3, we would need to validate a TC sample result, which
cannot be done without an appropriate conversion factor for EC.
We request comments on whether a five-year phase-in period for
lowering the final concentration limit to 160TC [mu]g/m3 complies with
Section 101(a)(9) of the Mine Act.
VIII. Section-by-Section Discussion of the Proposed Rule
A. Section 57.5060(b)
Section 57.5060(b) in the 2001 rule established a final
concentration limit of 160TC [mu]g/m3 to become
effective after January 19, 2006. In this rulemaking, we propose to
stagger the effective dates for implementation of the final DPM limit,
phased-in over a five year period. In a separate rulemaking, we will
propose changing the phased-in limits from TC to EC. As previously
discussed in Section IV, Technological Feasibility, issues have
surfaced since promulgation of the 2001 final rule that indicate the
mining industry, taken as a whole, may need additional time to address
implementation issues. We are still committed to ensuring that mine
operators continue the significant progress they have already
demonstrated in reducing miners' exposures to DPM. As a first step in
revising the final concentration limit, we are proposing the interim
PEL of 308 micrograms to remain in effect until January 20, 2007, based
on feasibility concerns with respect to compliance and sampling
strategy discussed above. MSHA is interested in whether the mining
community believes at this time that a reduction, after that date, of
the PEL equivalent by 50TC [mu]g/m3 each year from 400TC [mu]g/m3, is
feasible and will provide additional time for the implementation of
controls and development of distribution systems for alternative fuels.
We also request information and comments on mining industry current
experiences with feasibility of compliance with a limit lower than the
current interim PEL of 308 [mu]g/m3 of elemental carbon (EC).
The proposed rule would establish the existing interim PEL of
308TC [mu]g/m3 as the new final PEL for one year
until January 20, 2007, and impose limits that are reduced by what we
will determine in a separate rulemaking to be the equivalent of 50
micrograms of total carbon from 400TC [mu]g/m3
each succeeding year until the final PEL of 160TC [mu]g/
m3 is reached in 2011. Consistent with the 2005 final rule
on the interim limit, we propose to change the final limit from a
concentration limit to a PEL. We request comments on whether five years
is the correct timeframe for reducing miners' exposures to the 160
micrograms of TC as originally established in the 2001 standard and to
have been effective in January 2006. Also, we request information on
whether the proposed annual 50 microgram reductions of the final DPM
limit are appropriate or, in the alternative, should the final rule
include an approach such as one or two reductions.
We intend that the provisions regarding extensions of time in which
to meet the final concentration limit pursuant to existing Sec.
57.5060(c) would apply to the limits established in proposed Sec.
57.5060(b) effective January 20, 2006. If a mine requires additional
time to come into compliance with the revised limit of 308 EC for the
first year as in proposed Sec. 57.5060(b)(1) or with the final DPM
limit established in any other paragraph of proposed Sec. 57.5060(b)
due to technological or economic constraints, the operator of the mine
could file an application with our District Manager for a special
extension. We request your comments on the impact of granting
extensions for
[[Page 53289]]
compliance with exposure limits that are greater than the 160 TC final
limit.
We intend to cite a violation of the DPM exposure limit only when
we have solid evidence that a violation actually occurred. Accordingly,
we would continue to determine that an overexposure has occurred when a
sample exceeds the interim limit using an appropriate error factor. The
appropriate error factor would be slightly different for each of the
reduced PELs. Our error factor model accounts for both intra- and
inter-laboratory analytical variability and combines that variability
with variability in pump flow rate and other sampling and analytic
variables. The appropriate error factors will be based on the same
statistically sound paired-punch database as used for the existing
exposure limit. When developed, they will be further discussed on our
Web site at http://www.msha.gov under, ``Single Source Page for Metal
and Nonmetal Diesel Particulate Matter Regulations.''
B. Effect of Eliminating Sec. 57.5060(c)(3)(i)
The 2001 final rule included a requirement at Sec.
57.5060(c)(3)(i) specifying that applications for a one-year special
extension in which to comply with the final DPM concentration limit of
160 micrograms of TC include information adequate for the Secretary to
ascertain that diesel-powered equipment was used in the subject mine
prior to October 29, 1998. In our 2005 rule addressing the interim
limit, we revised the extension provisions, but we retained the October
29, 1998 factor for our District Manager to consider in granting
extensions. The basis for limiting special extensions to underground
mines that operated diesel-powered equipment prior to October 29, 1998
was that we released our NPRM of our 2001 final rule on that date. We
reasoned that some mines in operation prior to that date could
experience compliance difficulties relating to such factors as the
basic mine design, use of older equipment with high DPM emissions,
etc., and that as a result, some of these mines may require additional
time to attain compliance with the final DPM limit. Also, we envisioned
that mines opened after that date would be using cleaner engines that
would greatly benefit them in complying with the 2001 final
concentration limit. Now, we believe that our assumptions were
incorrect.
We now believe that it is unnecessary to limit the application of
extensions to mines operating diesel equipment prior to October 29,
1998, because under current Sec. 57.5060(c), it is voluntary as to
whether a mine operator applies for a special extension. Extensions
involve paperwork which result in a document that a mine operator can
rely on for one year (renewable) to show our inspectors that we have
determined that it is technologically or economically infeasible at
this time for that particular mine operator to achieve compliance with
the final limit using engineering and administrative controls. If their
miners are wearing respirators, they are in compliance and no citation
is issued. This is exactly the same test and the same result under
Sec. 57.5060(d) at mines without a formal extension. Under the current
rule, mine operators must use all feasible engineering and
administrative controls to achieve compliance. If we determine that
reaching the final limit is infeasible for technological or economic
reasons, and over-exposed miners are in respirators, the operator is
deemed to be in compliance and no citation is issued. We will
periodically check to determine current DPM exposures and the ability
of the mine operator to implement new control technology.
We request comments on the benefits of current Sec.
57.5060(c)(3)(i), and the effects of deleting the requirement, along
with the number of miners that would be affected if Sec.
57.5060(c)(3)(i) were eliminated. We also request comments on whether
the elimination of Sec. 57.5060(c)(3)(i) would result in a reduction
in the current level of health protection afforded to miners.
IX. Medical Evaluation and Transfer
We believe that the phase-in approach of this proposed rule for
ultimately reducing miners' exposures to 160 micrograms of total carbon
will resolve many of the existing feasibility issues related to
effectively implementing more engineering and administrative controls
in metal and nonmetal underground mines to enhance miners' health.
Consequently, fewer miners would be required to wear a respirator to
supplement feasible engineering and administrative controls. Whereas
most mines can feasibly comply with the existing DPM interim PEL of 308
micrograms of elemental carbon, we expect that some miners will
continue to have to wear respirators. With each lower limit, more
miners may have to wear respirators for longer time periods until
controls become feasible. In the event that miners cannot wear a
respirator, existing Sec. 57.5060(d) allows for the use of an air
purifying respirator, such as those that are integrated into a hardhat.
We believe that such respirators are an effective option under the
interim PEL for persons who cannot wear a negative-pressure respirator.
We are interested in comments from the mining community on whether
we should include in the final rule, pursuant to Section 101(a)(7) of
the Mine Act, a provision requiring a medical evaluation to determine a
miner's ability to use a respirator before the miner is fit tested or
required to work in an area of the mine where respiratory protection
must be used under the final limits. In addition, we are seeking
comments on whether the final rule should contain a requirement for
transfer of a miner to an area of the mine where respiratory protection
is not required if a medical professional has determined in the medical
evaluation that the miner is unable to wear a respirator for medical
reasons.
Currently, our standards do not require medical transfer of metal
and nonmetal miners. We are interested in whether the public believes
that we should amend the existing respiratory protection requirement at
Sec. 57.5060(d) by adding new paragraphs (d)(3) and (d)(4) that would
address medical evaluation and transfer rights for miners. We
particularly want to know if the final rule should include the
following language:
(3) The mine operator must provide a medical evaluation, at no
cost to the miner, to determine the miner's ability to use a
respirator before the miner is fit tested or required to use the
respirator to work at the mine.
(4) Upon notification from the medical professional that a
miner's medical examination shows evidence that the miner is unable
to wear a respirator, the miner must be transferred to work in an
existing position in an area of the same mine where respiratory
protection is not required.
(i) The miner must continue to receive compensation at no less
than the regular rate of pay in the classification held by that
miner immediately prior to the transfer.
(ii) The miner must receive wage increases based upon the new
work classification.
We also solicit comments from the public as to whether a transfer
provision in the final rule should address issues of notification to
the District Manager of the health professional's evaluation and the
fact that a miner will be transferred; the appropriate timeframe within
which the transfer must be made; whether a record of the medical
evaluation conducted for each miner should be maintained along with the
correct retention period; medical confidentiality; and any other
relevant issues such as costs to mine operators for implementing a rule
requiring medical evaluations and transfer of miners.
We preliminarily estimate that medical evaluation and transfer
requirements, as described above in
[[Page 53290]]
proposed Sec. 57.5060(d)(3) and (3)(4), would affect about 50 miners
annually for evaluation, about 3 miners annually for transfer, and cost
about $40,000 annually.
X. Regulatory Impact Analysis
A. Executive Order 12866
Executive Order 12866 requires regulatory agencies to assess both
the costs and benefits of regulations. In making this assessment, we
determined that this final rule will not have an annual effect of $100
million or more on the economy, and therefore is not an economically
significant regulatory action as defined by Sec. 3(f)(1) of E.O.
12866.
B. Costs
In Chapter IV of the Regulatory Economic Analysis in support of the
January 19, 2001 final rule (2001 REA), we estimated total yearly costs
to underground M/NM mines for the DPM final rule of $25,149,179 (p.
106). Of this amount, $6,612,464 was the discounted incremental yearly
cost of compliance with the final limit. The undiscounted incremental
yearly cost for compliance with the final limit was estimated as
$9,274,325 (p. 58).\1\
---------------------------------------------------------------------------
\1\ The following section, discussing benefits of the proposed
rule, notes that MSHA's original estimate, in 2001, of the benefits
of the final limit assumed that mean miner exposure to DPM was
larger than that observed in subsequent sampling of baseline and
current DPM concentrations experienced by underground M/NM miners.
To the extent that benefits were accordingly overestimated in 2001,
we expect that the 2001 estimates of cost impacts may have been
inflated similarly.
---------------------------------------------------------------------------
This proposed rule would amend the January 19, 2001 final DPM rule
by phasing in the 160TC [mu]g/m\3\ final limit over a five-
year period to address technological feasibility constraints that have
arisen. The discounted present value of the cost saving from this five-
year phase-in period would be $25,512,045, if compliance with the
160TC [mu]g/m\3\ final limit were technologically feasible
in 2006. The annualized value of this cost saving, using a discount
rate of 7%, would be $1,785,843. Table X-1 shows these calculations and
also shows the breakdown of these cost savings by mine size.
During the 4\1/2\ years since the 2001 final rule was promulgated,
the mining industry and MSHA have gained considerable experience with
the implementation, use, and cost of DPM control technology, which
could result in cost changes. Therefore, we solicit public comment
concerning the cost of compliance, including any changes in costs that
may have occurred since the 2001 REA.
[GRAPHIC] [TIFF OMITTED] TP07SE05.000
C. Benefits
In Chapter III of the Regulatory Economic Analysis in support of
the January 19, 2001 final rule (2001 REA), we demonstrated that the
DPM final rule for M/NM mines 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 of the risk to the
miners' families, to the miners' employers, and to society at large.
We have incorporated into this rulemaking record the previous DPM
rulemaking records, including the risk assessment to the January 19,
2001 standard. Benefits of the January 19, 2001 final rule include
continued reductions in lung cancers. In the long run, as the mining
population turns over, we estimated that a minimum of 8.5 lung cancer
deaths will be avoided per year. We 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 quantitative estimates examined in the January 19,
2001 final rule was 49 lung cancer deaths avoided per year.
[[Page 53291]]
Other benefits noted in the 2001 REA were reductions in the risk of
premature death from cardiovascular, cardiopulmonary, or respiratory
causes and reductions in the risk of sensory irritation and respiratory
symptoms. However, we did not include these health benefits in its
estimates because we could not make reliable or precise quantitative
estimates of them. Nevertheless, we noted that the expected reductions
in the risk of death from cardiovascular, cardiopulmonary, or
respiratory causes and the expected reductions in the risk of sensory
irritation and respiratory symptoms are likely to be substantial. You
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.
The 2001 risk assessment used the best available data on DPM
exposures at underground M/NM mines to quantify excess lung cancer
risk. ``Excess risk'' refers to the lifetime probability of dying from
lung cancer during or after a 45-year occupational DPM exposure. This
probability is expressed as the expected excess number of lung cancer
deaths per thousand miners occupationally exposed to DPM at a specified
mean DPM concentration. The excess is calculated relative to baseline,
age-specific lung cancer mortality rates taken from standard mortality
tables. In order to properly estimate this excess, it is necessary to
calculate, at each year of life after occupational exposure begins, the
expected number of persons surviving to that age with and without DPM
exposure at the specified level. At each age, standard actuarial
adjustments must be made in the number of survivors to account for the
risk of dying from causes other than lung cancer. Occupational exposure
is assumed to begin at age 20 and to continue, for surviving miners,
until retirement at age 65. The accumulation of lifetime excess risk
continues after retirement through the age of 85 years.
Table X-2, taken from the 2001 risk assessment, shows a range of
excess lung cancer estimates at mean exposures equal to the interim and
final DPM limits. The eight exposure-response models employed were
based on studies by Saverin et al. (1999), Johnston et al. (1997), and
Steenland et al. (1998). Assuming that TC is 80 percent of whole DPM,
and that the mean ratio of TC to EC is 1.3, the interim DPM limit of
500 [mu]g/m3 shown in Table X-2 corresponds to the 308
[mu]g/m3 EC surrogate limit adopted under the June 6, 2005
rulemaking.
Table X-2.--Excess Lung Cancer Risk Expected at Specified DPM Exposure
Levels Over an Occupational Lifetime (Extracted From Table III-7 of the
2001 Risk Assessment).
------------------------------------------------------------------------
Excess lung cancer deaths per
1000 occupationally exposed
workers [dagger]
Study and statistical model -------------------------------
Final DPM Interim DPM
limit 200 limit 500
[mu]g/m3 [mu]g/m3
------------------------------------------------------------------------
S[auml]verin et al. (1999)
Poisson, full cohort................ 15 44
Cox, full cohort.................... 70 280
Poisson, subcohort.................. 93 391
Cox, subcohort...................... 182 677
Steenland et al. (1998)
5-year lag, log of cumulative 67 89
exposure...........................
5-year lag, simple cumulative 159 620
exposure...........................
Johnston et al. (1997)
15-year lag, mine-adjusted.......... 313 724
15-year lag, mine-unadjusted........ 513 783
------------------------------------------------------------------------
[dagger] Assumes 45-year occupational exposure at 1920 hours per year
from age 20 to retirement at age 65. Lifetime risk of lung cancer
adjusted for competing risk of death from other causes and calculated
through age 85. Baseline lung cancer and overall mortality rates from
NCHS (1996).
As explained in the June 6, 2005 final rule, the mean DPM
concentration levels estimated from both the 31-Mine Study (432-492
[mu]g/m3, depending on whether trona mines are included) and
the baseline samples ([ap]320 [mu]g/m3) fall between the
interim and final DPM limits shown in Table X-2. All of the exposure-
response models shown are monotonic (i.e., increased exposure yields
increased excess risk, though not proportionately so). Therefore, using
the most current available estimates of mean exposure levels, they all
predict excess lung cancer risks somewhere between those shown for the
interim and final limits. Thus, despite substantial improvements
apparently attained since the 1989-1999 sampling period addressed by
the 2001 risk assessment, underground M/NM miners are still faced with
an unacceptable risk of lung cancer due to their occupational DPM
exposures.
Another principal conclusion of the 2001 risk assessment was:
By reducing DPM concentrations in underground mines, the rule
will substantially reduce the risks of material impairment faced by
underground miners exposed to DPM at current levels.
Although DPM levels have apparently declined since 1889-1999, MSHA
expects that further improvements will continue to significantly and
substantially reduce the health risks identified for miners. There is
clear evidence of DPM's adverse health effects, not only at pre-2001
levels but also at the generally lower levels currently observed at
many underground mines. These effects are material health impairments
as specified under Sec. 101(a)(6)(A) of the Mine Act. From the recent
enforcement sample results, 135 out of the 183 mines (73.8%) had at
least one sample exceeding the final exposure limit. Because the
exposure-response relationships shown in Table X-2 are monotonic, MSHA
expects that industry-wide implementation of the interim limit will
significantly reduce the risk of lung cancer among miners.
This proposed rule would amend the January 19, 2001 final DPM rule
by phasing in the final limit over a five-year period to address
technological feasibility constraints that have arisen. By addressing
the technological feasibility issues in this way, this proposed rule
would contribute to the
[[Page 53292]]
realization of the benefits mentioned above.
XI. 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,
we 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, we establish a definition which is appropriate to our
activities and publish that definition in the Federal Register. For the
mining industry, SBA defines ``small'' as having 500 or fewer workers.
We have traditionally considered small mines to be those with fewer
than 20 workers.
To ensure that the rule conforms to the RFA, we analyzed the
economic impact on mines with 500 or fewer workers and also on mines
with fewer than 20 workers. In Chapter V of the 2001 REA we estimated
yearly revenues for these mine sizes. In Table X-1 of this preamble, we
estimate the cost savings to mines of various employment sizes. In
Table XI-1 of this preamble we combine these numbers and calculate cost
savings as a percentage of revenues. Cost savings are 0.25% of revenues
for mines with fewer than 20 employees and 0.06% of revenues for mines
with 500 or fewer employees. Since both cost savings calculations are
less than one percent of revenues, there is no need to conduct an
initial regulatory flexibility analysis. We solicit public comment
concerning the accuracy of these cost estimates.
We certify that the rule will not have a significant economic
impact on a substantial number of small entities under either
definition.
[GRAPHIC] [TIFF OMITTED] TP07SE05.001
XII. Paperwork Reduction Act
There are no paperwork provisions in this proposed rule.
XIII. Other Regulatory Considerations
A. National Environmental Policy Act of 1969
We have reviewed this proposed rule in accordance with the
requirements of the National Environmental Policy Act (NEPA) of 1969
(42 U.S.C. 4321 et seq.), the regulations of the Council on
Environmental Quality (40 U.S.C. part 1500), and the Department of
Labor's NEPA procedures (29 CFR part 11).
This proposed rule would have no significant impact on air, water,
or soil quality; plant or animal life; the use of land; or other
aspects of the human environment. As a result of this environmental
assessment, we find that the proposed rule would have no significant
impact on the human environment. Accordingly, we have not provided an
environmental impact statement. We solicit public comment concerning
the accuracy and completeness of this environmental assessment.
B. The Unfunded Mandates Reform Act of 1995
This proposed rule does not include any Federal mandate that may
result in increased expenditures by State, local, or tribal
governments, nor would it increase private sector expenditures by more
than $100 million annually, nor would it significantly or uniquely
affect small governments. Accordingly, the Unfunded Mandates Reform Act
of 1995 (2 U.S.C. 1501 et seq.) requires no further agency action or
analysis.
C. The Treasury and General Government Appropriations Act of 1999:
Assessment of Federal Regulations and Policies on Families
This proposed rule would have no affect on family well-being or
stability, marital commitment, parental rights or authority, or income
or poverty of families and children. Accordingly, Section 654 of the
Treasury and General Government Appropriations Act of 1999 (5 U.S.C.
601 note) requires no further agency action, analysis, or assessment.
D. Executive Order 12630: Government Actions and Interference With
Constitutionally Protected Property Rights
This proposed rule would not implement a policy with takings
implications. Accordingly, Executive Order 12630, Governmental Actions
and Interference with Constitutionally Protected Property Rights,
requires no further agency action or analysis.
E. Executive Order 12988: Civil Justice Reform
This proposed rule was written to provide a clear legal standard
for affected conduct and was carefully reviewed to eliminate drafting
errors and ambiguities, so as to minimize litigation and undue burden
on the Federal court system. Accordingly, this proposed rule would meet
the applicable standards provided in Section 3 of Executive Order
12988, Civil Justice Reform.
F. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
This proposed rule would have no adverse impact on children.
Accordingly, Executive Order 13045, Protection of Children from
Environmental Health Risks and Safety Risks, as amended by Executive
Orders 13229 and 13296, requires no further agency action or analysis.
G. Executive Order 13132: Federalism
This proposed rule would not have ``federalism implications,''
because it 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.'' Accordingly, Executive Order 13132,
[[Page 53293]]
Federalism, requires no further agency action or analysis.
H. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This proposed rule would not have ``tribal implications,'' because
it would not ``have substantial direct effects on one or more Indian
tribes, on the relationship between the Federal government and Indian
tribes, or on the distribution of power and responsibilities between
the Federal government and Indian tribes.'' Accordingly, Executive
Order 13175, Consultation and Coordination with Indian Tribal
Governments, requires no further agency action or analysis.
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
Regulation of the metal/nonmetal sector of the mining industry has
no significant impact on the supply, distribution, or use of energy.
This proposed rule is not a ``significant energy action,'' because it
would not be ``likely to have a significant adverse effect on the
supply, distribution, or use of energy * * * (including a shortfall in
supply, price increases, and increased use of foreign supplies).''
Accordingly, Executive Order 13211, Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use, requires no
further agency action or analysis.
J. Executive Order 13272: Proper Consideration of Small Entities in
Agency Rulemaking
We have thoroughly reviewed this proposed rule to assess and take
appropriate account of its potential impact on small businesses, small
governmental jurisdictions, and small organizations. As discussed in
Section XI of this preamble, we have determined and certified that this
proposed rule would not have a significant economic impact on a
substantial number of small entities. Accordingly, Executive Order
13272, Proper Consideration of Small Entities in Agency Rulemaking,
requires no further agency action or analysis.
XIV. Proposed Rule Text
List of Subjects in 30 CFR Part 57
Diesel particulate matter, Metal and nonmetal, Mine safety and
health, Underground miners.
Dated: September 1, 2005.
David G. Dye,
Deputy Assistant Secretary of Labor for Mine Safety and Health.
For reasons set forth in the preamble, we propose to amend Chapter
1 of Title 30 as follows:
PART --57 [AMENDED]
1. The authority citation for part 57 reads follows:
Authority: 30 U.S.C. 811
2. Section 57.5060 is amended by revising paragraph (b) and
removing paragraph (c)(3)(i) to read as follows:
Sec. 57.5060 Limit on exposure to diesel particulate matter.
* * * * *
(b)(1) Effective January 20, 2006, a miner's personal exposure to
diesel particulate matter (DPM) in an underground mine must 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/m\3\).
(2) Effective January 20, 2007, a miner's personal exposure to
diesel particulate matter (DPM) in an underground mine must not exceed
an average eight-hour equivalent full shift airborne concentration of
350 micrograms of total carbon per cubic meter of air (350TC
[mu]g/m\3\).
(3) Effective January 20, 2008, a miner's personal exposure to
diesel particulate matter (DPM) in an underground mine must not exceed
an average eight-hour equivalent full shift airborne concentration of
300 micrograms of total carbon per cubic meter of air (300TC
[mu]g/m\3\).
(4) Effective January 20, 2009, a miner's personal exposure to
diesel particulate matter (DPM) in an underground mine must not exceed
an average eight-hour equivalent full shift airborne concentration of
250 micrograms of total carbon per cubic meter of air (250TC
[mu]g/m\3\).
(5) Effective January 20, 2010, a miner's personal exposure to
diesel particulate matter (DPM) in an underground mine must not exceed
an average eight-hour equivalent full shift airborne concentration of
200 micrograms of total carbon per cubic meter of air (200TC
[mu]g/m\3\).
(6) Effective January 20, 2011, a miner's personal exposure to
diesel particulate matter (DPM) in an underground mine must not exceed
an average eight-hour equivalent full shift airborne concentration of
160 micrograms of total carbon per cubic meter of air (160TC
[mu]g/m\3\).
* * * * *
[FR Doc. 05-17802 Filed 9-6-05; 8:45 am]
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