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PI: K. Ito; Co-I: A. Nadas; Consultant: G.D. Thurston.
Our objectives are to:
- quantitatively characterize spatio-temporal error of PM components and gaseous co-pollutants measured at the routine regulatory-based air monitors as a function of site characteristics using the entire U.S. air monitoring network;
- establish the relationship between the estimated error at a given monitoring site and the effect size/significance in mortality and morbidity models; and
- evaluate the relative contribution of the error due to site-to-site and person-to-site variability.
We will first characterize spatio-temporal variation of PM at metropolitan and regional scales for the entire U.S. between 1985 and 1994 (n = approximately 900 sites for PM10; n = approximately 40 sites for PM2.5). The site-to-site correlation of temporal variation will be modeled as a function of qualitative (e.g., location setting) and quantitative (e.g., distance to and quantity of emission sources) variables. The second stage of this project will investigate the relationship between the estimated exposure characterization error associated with a given site's data and its effect size/significance in health effects models for MSAs or regions where a large number (10-30 sites) of monitors are available (approximately 20 regions covering over 70 million residents). In addition, as data become available from the ongoing EPA-funded NYUSOM PM personal exposure study in NYC in 1999, we will be able to determine the error associated with person-to-central monitor difference, and to evaluate the relative importance of these two types of errors. The initial analyses for PM10 and PM2.5 will set the stage for the later analyses for PM constituents data that will become available to Center investigators in the next few years. The results will help in the design future population exposure monitoring systems (e.g., location of monitors, sampling frequencies) for epidemiological purposes and compliance monitoring.
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