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THE INFLUENCE OF HUMAN ACTIVITY PATTERNS ON PERSONAL PM EXPOSURE: A COMPARATIVE ANALYSIS OF FILTER-BASED AND CONTINUOUS PARTICLE MEASUREMENTS
Citation:
Rea, A W., M J. Zufall, R W. Williams, L S. Sheldon, AND C HowardReed. THE INFLUENCE OF HUMAN ACTIVITY PATTERNS ON PERSONAL PM EXPOSURE: A COMPARATIVE ANALYSIS OF FILTER-BASED AND CONTINUOUS PARTICLE MEASUREMENTS. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION 51(9):1271-1279, (2001).
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:
Particulate matter (PM) exposure data from the U.S. Environmental Protection Agency sponsored 1998 Baltimore and 1999 Fresno PM Exposure Studies were analyzed to identify important microenvironments and activities that may lead to increased particle exposure for select elderly (>65 years old) subjects. Integrated 24-hour filter-based PM2.5 and/or PM10 mass measurements (using Personal Environmental Monitors or PEMs) included personal, indoor and outdoor residential measurements, and measurements at a central indoor site and a community monitoring site. A subset of the participants in each study wore passive nephelometers that continuously measured (1 -min averaging time) particles ranging in size from 0.1 to ~10 um. Significant activities and locations were identified by a statistical mixed model (p<0.01) for each study population based on the measured PM2.5 or PM10 mass and time activity data. Elevated PM concentrations were associated with traveling (car or bus), commercial locations (store, office, mall, etc.), restaurants, and working. The modeled results were compared to continuous PM concentrations determined by the nephelometers while participants were in these locations. Overall, the nephelometer data agreed within 6% of the modeled PM2.5 results for the Baltimore participants and ~20% for the Fresno participants (variability was due to zero drift associated with the nephelometer). The nephelometer did not agree as well with the PM10 mass measurements, most likely because the nephelometer optimally responds to fine particles (0.3-2 um). Approximately half (54 + or - 31%; mean + or - std. dev. from both studies) of the average daily PM2.5 exposure occurred inside residences, where the participants spent an average of 83 + or - 10% of their time. These data also showed that a significant portion of PM2.5 exposure occurred in locations where participants spent only 4-13% of their time.
The information in this document has been funded wholly or in part by the United States Environmental Protection Agency through Contract #68-D5-0040 to the Research Triangle Institute. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use.