摘要：Objectives. To quantify nationwide disparities in the location of particulate matter (PM)-emitting facilities by the characteristics of the surrounding residential population and to illustrate various spatial scales at which to consider such disparities. Methods. We assigned facilities emitting PM in the 2011 National Emissions Inventory to nearby block groups across the 2009 to 2013 American Community Survey population. We calculated the burden from these emissions for racial/ethnic groups and by poverty status. We quantified disparities nationally and for each state and county in the country. Results. For PM of 2.5 micrometers in diameter or less, those in poverty had 1.35 times higher burden than did the overall population, and non-Whites had 1.28 times higher burden. Blacks, specifically, had 1.54 times higher burden than did the overall population. These patterns were relatively unaffected by sensitivity analyses, and disparities held not only nationally but within most states and counties as well. Conclusions. Disparities in burden from PM-emitting facilities exist at multiple geographic scales. Disparities for Blacks are more pronounced than are disparities on the basis of poverty status. Strictly socioeconomic considerations may be insufficient to reduce PM burdens equitably across populations. The inequitable distribution of hazardous sites such as landfills and industrial facilities is one of the longest-standing concerns in the field of environmental justice. More than 3 decades ago in one of the earliest environmental justice studies, the US government reported a disproportionately high representation of socially disadvantaged populations residing in communities near landfills. 1 Disparities in residential proximity to pollution sources have been evaluated in terms of income level and poverty as well as race/ethnicity. A nationally representative 1986 sample found that Blacks were 1.54 times more likely than were Whites to live within 1 mile of a facility listed in the Toxics Release Inventory—a gap that remained statistically significant even after accounting for income and education level. 2 The distributions of specific air pollutants, and not just the facilities emitting them, also reflect racial disparities. For example, mean residential ambient nitrogen dioxide concentrations in 2010 were about 7% higher for those in poverty than for those above the poverty line, whereas the disparity for non-Whites (37% higher concentrations than for Whites) was substantially greater. 3 There is considerable evidence concerning human health impacts of residential proximity to facilities emitting air pollutants. 4 One such pollutant is particulate matter (PM), a mixture of solid and liquid particles suspended in the air. 5 Exposure to PM10 (PM ≤ 10 µm in diameter) and especially to PM2.5 (PM ≤ 2.5 µm in diameter) has been associated with a number of health effects, including respiratory and cardiovascular diseases as well as premature mortality. 6–8 Although proximity to facilities emitting PM is not a direct measure of exposure, it is a valuable metric. Unlike natural events that contribute to ambient PM, such as wildfires, the siting of a facility is the result of a decision-making process. Disparities in siting may indicate underlying disparities in the power to influence that process. For example, an Environmental Protection Agency (EPA) investigation in Flint, Michigan, found a direct link between racial discrimination and the permitting of a power station there, stating, “The preponderance of evidence supports a finding of discriminatory treatment of African Americans by [the Department of Environmental Quality] in the public participation process.” 9 We aimed to quantify nationwide disparities in the distribution of PM-emitting facilities by the characteristics of the surrounding residential populations and to illustrate various spatial scales at which to consider such disparities. Previous literature has shown that non-Whites and below-poverty individuals are more likely to reside near stationary sites of PM2.5 emissions 10 ; we sought to update and expand on these findings.
