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SUMMARY FINDINGS FROM THE U.S. EPA'S PARTICULATE MATTER PANEL STUDIES
Citation:
Sheldon, L S., R W. Williams, J C. Suggs, G F. Evans, A W. Rea, A F. Vette, J M. Burke, C Croghan, K W. Leovic, J P. Creason, D Walsh, C. Rodes, J. Thornburg, P. Lawless, A. Ejire, AND W. Sanders Jr. SUMMARY FINDINGS FROM THE U.S. EPA'S PARTICULATE MATTER PANEL STUDIES. Presented at International Society of Exposure Analysis 2002 Conference, Vancouver, Canada, August 11-15, 2002.
Impact/Purpose:
The primary study objectives are:
1.To quantify personal exposures and indoor air concentrations for PM/gases for potentially sensitive individuals (cross sectional, inter- and intrapersonal).
2.To describe (magnitude and variability) the relationships between personal exposure, and indoor, outdoor and ambient air concentrations for PM/gases for different sensitive cohorts. These cohorts represent subjects of opportunity and relationships established will not be used to extrapolate to the general population.
3.To examine the inter- and intrapersonal variability in the relationship between personal exposures, and indoor, outdoor, and ambient air concentrations for PM/gases for sensitive individuals.
4.To identify and model the factors that contribute to the inter- and intrapersonal variability in the relationships between personal exposures and indoor, outdoor, and ambient air concentrations for PM/gases.
5.To determine the contribution of ambient concentrations to indoor air/personal exposures for PM/gases.
6.To examine the effects of air shed (location, season), population demographics, and residential setting (apartment vs stand-alone homes) on the relationship between personal exposure and indoor, outdoor, and ambient air concentrations for PM/gases.
Description:
The U.S. EPA's Particulate Matter Panel Studies were a series of longitudinal human exposure studies used to characterize personal exposures to particulate matter (PM) and related co-pollutants to that of pollutants of ambient origin. Participants were monitored over time (28 days) to investigate both longitudinal and cross-sectional correlations between personal, residential indoor, residential outdoor, and ambient measurements. The studies involved 75 volunteers from Baltimore, Maryland (1998); Fresno, California (1999) and Research Triangle Park, North Carolina (2002-2001) and were designed to evaluate different sub-populations, regions of the country, seasons, and housing conditions. Susceptible sub-populations ( 55 years old) included healthy individuals along with a majority having various pulmonary and cardiovascular diseases. Daily PM2.5 and/or PM10 mass concentrations were determined in each study. Copollutants included CO, O3, NO2, SO2, and metals. Information on time/activity patterns and potential sources of PM exposure were collected for each participant through daily survey/questionnaire instruments. A total of more than 7000 PM mass measurements were obtained. Data indicates that the magnitude and variability of personal PM2.5 exposures can vary significantly (3 to 200 ug/m3) depending upon individual activity patterns and exposure factors such as season, geographical setting and/or housing conditions. The same holds true for spatial associations (eg., personal to ambient mass correlations varied between 0.0 to 0.95). Mean personal PM2.5 clouds from 3 to 10 ug/m3 were observed in the different participant populations. Estimations of outdoor source contributions to personal PM2.5 mass concentrations using a number of mixed modeling effects ranged from 8 to 10 ug/m3 in the latest Research Triangle Park-based study. These data indicate that ambient PM2.5 sources typically contributed approximately 50% to the total personal exposure mass concentration. Methodologies employed to collect data concerning potential contributions from other sources (eg., cooking, household cleaning) to personal PM exposures based on real-time personal and indoor nephelometry data will be reported. Development of the new techniques to estimate personal monitoring compliance using activity sensors and procedures to determine the impact of HVAC duty cycles upon individual residences will also be presented.
This work has been funded wholly by the United States Environmental Protection Agency under contract #68-D5-0040 and 68-D-99-012 to the Research Triangle Institute and assistance agreement #CR-828186-01-0 to Shaw University. It has been subjected to Agency review and approved for publication.