Inequities in Air Pollution Exposure in the U.S.: An Exploration of Disparity Metrics Across Geographic and Temporal Scales

Abstract

In the United States (U.S.), exposure to ambient 𝑃𝑀₂.₅ – fine particulate matter smaller than 2.5 micrometers in diameter– is responsible for the largest share of premature deaths associated with air pollution. Despite declines in average annual concentrations, significant disparities in 𝑃𝑀₂.₅ exposure between racial and ethnic groups continue to persist. Existing research characterize 𝑃𝑀₂.₅ exposure disparities across a range of different indicators, but few studies compare these metrics against one another nor do these studies explore these metrics at different geographic scales and demographic shifts over time. As policy makers begin to prioritize environmental justice concerns through the identification of disproportionately impacted communities, careful selection of indicators and metrics will be vital for ensuring that inequities are properly captured in decision making processes.

Using population demographics from the U.S. Census and land-use regression 𝑃𝑀₂.₅ concentration estimates from the Center for Air, Climate, and Energy Solutions (CACES), we compare the calculations of absolute and relative exposure disparities at different geographic scales and changing demographic shifts. Further, we discuss the policy implications of our findings and provide recommendations for both regulatory and community centered measures to address existing racial/ethnic disparities.