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(TUCSON) STUDY DESIGN AND PRELIMINARY EXPOSURE FINDINGS ASSOCIATED WITH THE DEARS
Citation:
WILLIAMS, R. W., A. F. VETTE, C. W. CROGHAN, C. D. STEVENS, D. A. WHITAKER, W. A. MCCLENNY, R. C. FORTMANN, L. S. SHELDON, A. W. REA, H. WILSON, C. RHODES, J. THORNBURG, K. EDGREN, AND M. HEINDORF. (TUCSON) STUDY DESIGN AND PRELIMINARY EXPOSURE FINDINGS ASSOCIATED WITH THE DEARS. Presented at International Society of Exposure Analysis Conference, Tucson, AZ, October 30 - November 03, 2005.
Impact/Purpose:
Six objectives have been defined for this study.
(1) To determine the associations between concentrations measured at central site monitors and outdoor residential, indoor residential and personal exposures for selected air toxics, PM constituents, and PM from specific sources.
(2) To describe the physical and chemical factors that affect the relationship between central site monitors and outdoor residential and indoor residential concentrations, including those that affect ambient source impacts.
(3) To identify the human activity factors that influence personal exposures to selected PM constituents and air toxics.
(4) To improve and evaluate models used to characterize and estimate residential concentrations of and human exposures to selected air toxics, PM constituents, and PM from specific sources.
(5) To investigate and apply source apportionment models to evaluate the relationships for PM from specific sources and to determine the contribution of specific ambient sources to residential concentrations and personal exposures to PM constituents and air toxics.
(6) To determine the associations between ambient concentrations of criteria gases (O3, NO2, and SO2) and personal exposures for these gases as well as personal exposures to air toxics, PM constituents, and PM from specific sources.
Description:
The Detroit Exposure and Aerosol Research Study (DEARS) is a three-year field monitoring study initiated in 2004 that is designed to measure exposure and describe exposure relationships for air toxics, PM components, PM from specific sources, and criteria pollutants. Detroit, Michigan was considered the best candidate for this study because of its current and projected future non-attainment status for PM2.5, the number of point and mobile source influences present, its geographic location, meteorology, ambient monitoring networks, potential state and local collaborations, and community-based partnerships. The DEARS will examine the spatial variability of PM2.5 and its components to determine the suitability of conducting health outcome studies using a central site monitor in an urban area like Detroit where there are many point sources. Source apportionment techniques will be used to evaluate the relationship between PM and air toxics from specific sources. The DEARS is designed to examine and quantify the impact of local ambient sources on the relationship between central site monitors and exposures. Personal, residential indoor and residential outdoor monitoring for a variety of PM and air toxics will be performed. Survey information will be collected on household characteristics, heating and air conditioning system operation, local ambient sources, indoor and personal sources, and time-activity patterns. Residences in seven ambient source-impacted areas (mobile sources, point sources, and a control) will be monitored for 5 days in each of 2 seasons (summer, winter). A total of 120 residences will be monitored over 3 years for a total of 1200 household-person/days. A Speciation Trends Network site, Allen Park, has been selected as the central site monitor for this study. A description of the study design and preliminary PM data will be presented here. Preliminary findings from the summer 2004 monitoring period indicate that personal PM2.5 mass concentrations ranged from 3 to 125 µg/m3. Residential outdoor PM2.5 mass concentrations were determined to be fairly uniform (~ 17 µg/m3)in source-impacted areas. Particle-bound ammonium nitrate concentrations (~ 1 µg/m3) were found to be less variable than elemental carbon (1 to 2 µg/m3). The latter might reflect the influence of local line sources within the various study areas.
Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.