TITLE
Development of an Active Personal Ozone Sampler Using a Hollow Tube
Diffusion Denuder

AUTHOR(S)
A. Geyh, J. Wolfson, P. Koutrakis, and J. Mulik

PERFORMING ORGANIZATION NAME AND ADDRESS
Harvard School of Public Health
665 Huntington Ave
Boston, MA

SPONSORING AGENCY NAME AND ADDRESS
Atmospheric Research and Exposure Assessment Laboratory
Office of Research and Development
US Environmental Protection Agency
Research Triangle Park, NC  27711

ABSTRACT
     Personal, microenvironmental and indoor ozone monitoring is
currently conducted using a lightweight, inexpensive passive
sampling device.  Although the passive device is adequate for many
studies, we are developing a relatively light weight active hollow
tube diffusion denuder system which increases the sensitivity of
ozone measurements and reduces effects associated with variations
in wind velocity, for improved personal monitoring.

     The new hollow tube denuder (HTD) system consists of a 1.4(ID)
x 10(L) cm etched borosilicate glass tube attached to a small, low-
flow, relatively inexpensive personal pump.  Tube diameter and
length were chosen to maximize collection efficiency at a sampling
rate of 65 mL/min.  The tube is coated with nitrite reagent which
has been successfully used with passive ozone samplers.

     Variations in relative humidity, ozone concentration, and
total ozone exposure have relatively small effects on the accuracy
and precision of the HTD.  In addition, the low limit of detection
(LOD) of approximately 45 ppb.hrs yields a 4-fold increase in
sensitivity over the passive samplers for which a 200 ppb.hr LOD
has been determined.  This new active sampler thus allows improved
short-term personal and microenvironmental monitoring.