Source-specific Contributions to Racial-Ethnic Disparities in Ambient Fine Particulate Matter Exposure in the United States

Abstract:

Racial-ethnic minorities in the United States are exposed to disproportionately high levels of fine particulate air pollution (PM_2.5), a major environmental cause of human mortality. Here, we use the InMAP reduced complexity air quality model and the year-2014 EPA National Emissions Inventory to comprehensively evaluate and prioritize the emission source-types leading to these disparities. For most race-ethnicities and locations we study, industrial emissions are the largest source of absolute disparity in exposure, whereas residential gas combustion and commercial cooking cause large relative disparities. A majority of emissions sources disproportionately expose people of color to harmful air pollution nationally—11 out of the 14 emissions source categories studied and over 70% and 68% of total PM_2.5 exposure (3,065 out of 5,806 individual source types). So for most locations and source types, reducing emissions could be expected to lead to reductions in racial-ethnic exposure disparities. However, the amount of absolute disparity caused by a given source type, and the relative amount of disparity reduction possible per unit of decreased emissions, can vary widely by location. For example, we find that industrial emissions are the largest source of absolute exposure inequity in most locations, but in New York it is residential gas combustion. Additionally, commercial cooking is a relatively small source of absolute inequity in most locations, but in Philadelphia it is the second largest. We hope that the information provided by this study can serve to guide national, state, and city agencies to design policies to efficiently reduce environmental inequity.