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The Importance of Population Susceptibility for Air Pollution Risk Assessment: A Case Study of Power Plants Near Washington, DC
Jonathan I. Levy, Susan L. Greco, and John D. Spengler Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA Abstract
In evaluating risks from air pollution, health impact assessments often focus on the magnitude of the impacts without explicitly considering the distribution of impacts across subpopulations. In this study, we constructed a model to estimate the magnitude and distribution of health benefits associated with emission controls at five older power plants in the Washington, DC, area. We used the CALPUFF atmospheric dispersion model to determine the primary and secondary fine-particulate-matter (< 2.5 µm in aerodynamic diameter) concentration reductions associated with the hypothetical application of "Best Available Control Technology" to the selected power plants. We combined these concentration reductions with concentration-response functions for mortality and selected morbidity outcomes, using a conventional approach as well as considering susceptible subpopulations. Incorporating susceptibility had a minimal effect on total benefits, with central estimates of approximately 240 fewer premature deaths, 60 fewer cardiovascular hospital admissions (CHA) , and 160 fewer pediatric asthma emergency room visits (ERV) per year. However, because individuals with lower education appear to have both higher background mortality rates and higher relative risks for air-pollution-related mortality, stratifying by educational attainment implies that 51% of the mortality benefits accrue among the 25% of the population with less than high school education. Similarly, diabetics and African Americans bear disproportionate shares of the CHA and ERV benefits, respectively. Although our ability to characterize subpopulations is constrained by the available information, our analysis demonstrates that incorporation of susceptibility information significantly affects demographic and geographic patterns of health benefits and enhances our understanding of individuals likely to benefit from emission controls. Key words: asthma emergency department visits, cardiovascular hospital admissions, diabetes, education, mortality, particulate matter, power plant, risk assessment, susceptibility. Environ Health Perspect 110:1253-1260 (2002) . [Online 29 October 2002] http://ehpnet1.niehs.nih.gov/docs/2002/110p1253-1260levy/ abstract.html Address correspondence to J.I. Levy, Landmark Center Room 404K, 401 Park Drive, PO Box 15677, Boston, MA 02215 USA. Telephone: (617) 384-8808. Fax: (617) 384-8859. E-mail: jilevy@hsph.harvard.edu We thank D. Hlinka, D. Sullivan, and D. Moon for their assistance in the atmospheric dispersion modeling ; B. Egan, R. Paine, D. Heinold, F. Cameron, J. Samet, and J. Scire for providing helpful feedback on related manuscripts ; and R. Tangirala for bringing an error to our attention. This study was commissioned by the Clean Air Task Force and prepared with support from the Pew Charitable Trusts and the Kresge Center for Environmental Health (NIEHS ES000002) . Received 4 November 2001 ; accepted 21 May 2002.
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