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THE RESEARCH TRIANGLE PARK PARTICULATE MATTER PANEL STUDY: MODELING AMBIENT SOURCE CONTRIBUTION TO PERSONAL AND RESIDENTIAL PM MASS CONCENTRATIONS
Citation:
Williams, R W., J C. Suggs, A W. Rea, L S. Sheldon, C. Rodes, AND J. Thornburg. THE RESEARCH TRIANGLE PARK PARTICULATE MATTER PANEL STUDY: MODELING AMBIENT SOURCE CONTRIBUTION TO PERSONAL AND RESIDENTIAL PM MASS CONCENTRATIONS. ATMOSPHERIC ENVIRONMENT 37(36):5365-5378, (2003).
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 Research Triangle Park (RTP) Particulate Matter (PM) Panel Study represented a one-year investigation of personal, residential and ambient PM mass concentrations across distances as large as 70 km in central North Carolina. One of the primary goals of this effort was to estimate ambient PM2.5 contributions to personal and indoor residential PM mass concentrations. Analyses indicated that data from the two distinct non-smoking subject populations totaling 38 individuals and 37 residences could be pooled. This resulted in nearly 800 data points for each variable. A total of 55 measurements believed to have been potentially influenced by personal or residential exposure to passive environmental tobacco smoke were not included in the analysis database. Variables to be examined included Cig (concentration of indoor generated PM), Eig (personal exposure to indoor generated PM), Finf (ambient PM infiltration factor), and Fpex (personal exposure to PM of ambient origin factor). Daily air exchange rates (AER) were measured and statistical modeling to derive estimates of particle penetration (P) and particle deposition (k) factors was performed. Seasonality, cohort grouping, participant or combinations of these variables were determined not to be significant influences in estimating group infiltration factors. The mean (+/- std) mixed model slope estimates were AER = 0.72 +/- 0.63, P = 0.72 +/- 0.21, k = 0.42 +/- 0.19, and Finf = 0.45 +/- 0.21. These variables were then used in a number of mixed effects models having varying features of single, random or fixed intercepts and/or slopes to determine the most appropriate means of estimating ambient source contributions to personal and residential settings. A mixed model slope for Fpex (+/- SE) was 0.47 +/- 0.07 using the model with the highest degree of fit.
The US Environmental Protection Agency through its Office of Research and Development funded and conducted the research described here. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use