Analysis of the Distribution of Cumulative Air Toxic Concentrations in the United States. T. J. Woodruff and D. A. Axelrad, U.S. Environmental Protection Agency, Office of Policy, Planning and Evaluation, 401 M St. SW (2123), Washington, DC 20460; A. S. Rosenbaum, Systems Applications International, Inc., 101 Lucas Valley Road, San Rafael, CA 94903; J. C. Caldwell, U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711; and R. A. Morello-Frosch, UC Berkeley School of Public Health, Environmental Health Sciences Division, 140 Warren Hall, Berkeley, CA 94720
EPA is conducting an assessment of cumulative concentrations of hazardous air pollutants (HAPs, or "air toxics") across the United States to gain a greater understanding of their geographic distribution. Cumulative annual-average ambient concentrations are modeled for approximately 150 HAPs for each census tract in the contiguous United States. For each census tract, modeled ambient concentrations are compared to health safety benchmarks for cancer, chronic noncancer, and acute health effects for each HAP. This analysis is used to identify areas in the United States having air toxic concentrations in excess of these benchmarks. Comparisons of ambient air toxics concentrations to health safety benchmarks shows that, for a number of toxics, a majority of census tracts have estimated ambient concentrations greater than a health safety benchmark. The most frequently exceeded benchmarks are for cancer concerns. Further evaluation of the sources of air toxics and of individual air toxics that have the highest potential public health impact will be presented. In addition, methodologies developed for aggregating toxicity information for multiple HAPs will be used to identify additional areas with potential public health impacts.
The views expressed in this presentation are those of the authors, and do not necessarily represent those of the U.S. Environmental Protection Agency.