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Development and Evaluation of Alternative Metrics of Ambient Air Pollution Exposure for Use in Epidemiologic Studies
Citation:
ISAKOV, V., J. L. CROOKS, J. TOUMA, M. Valari, H. A. OZKAYNAK, S. E. SARNAT, J. SARNAT, P. Kewada, AND J. MULHOLLAND. Development and Evaluation of Alternative Metrics of Ambient Air Pollution Exposure for Use in Epidemiologic Studies. Chapter 111, Douw G. Steyn & Silvia Trini Castelli (ed.), Air Pollution Modeling and its Application XXI. Springer Netherlands, , Netherlands, Series C:681--686, (2011).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL′s) Atmospheric Modeling and Analysis Division (AMAD) conducts research in support of EPA′s mission to protect human health and the environment. AMAD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.
Description:
Population-based epidemiologic studies of air pollution have traditionally relied upon imperfect surrogates of personal exposures, such as area-wide ambient air pollution levels based on readily available outdoor concentrations from central monitoring sites. This practice may introduce exposure misclassification in epidemiologic analyses for pollutants that are spatially heterogeneous, including those associated with traffic emissions (ie.. carbon monoxide, elemental carbon. nitrogen oxides, and particulate matter). To investigate the potential impact of misclassification within observed health risk estimates, U.S. EPA in collaboration with Emory University is developing and evaluating several tiers of exposure metrics for ambient traffic-related and regional pollutants that vary in their approaches for modeling pollutant spatial heterogeneity. The following tiers of exposure metrics are examined: 1) central site monitoring data, 2) local scale modeling (AERMOD), and 3) combined regional and local scale modeling. Each metric is applied in two extensive, ongoing epidemiologic studies conducted by Emory University to examine ambient air pollution and acute morbidity in Atlanta, GA. We hypothesize that using the more refined exposure estimates will provide greater power to detect epidemiologic associations of interest, particularly for heterogeneous, traffic-related pollutants. This research will be useful for improving exposure assessment in future air pollution epidemiology studies, by providing alternative methods as well as by providing a further understanding of to the situations that might require refined exposure metrics.