What Caused Racial Disparities in Particulate Exposure to Fall? New Evidence from the Clean Air Act and Satellite-Based Measures of Air Quality
Racial differences in exposure to ambient air pollution have declined significantly in the United States over the past 20 years. This project links restricted-access Census Bureau microdata to newly available, spatially continuous high resolution measures of ambient particulate pollution (PM2.5) to examine the underlying causes and consequences of differences in black-white pollution exposures. We begin by decomposing differences in pollution exposure into components explained by observable population characteristics (e.g., income) versus those that remain unexplained. We then use quantile regression methods to show that a significant portion of the "unexplained" convergence in black-white pollution exposure can be attributed to differential impacts of the Clean Air Act (CAA) in non-Hispanic African American and non-Hispanic white communities. Areas with larger black populations saw greater CAA-related declines in PM2.5 exposure. We show that the CAA has been the single largest contributor to racial convergence in PM2.5 pollution exposure in the U.S. since 2000, accounting for over 60 percent of the reduction.
This paper is released to inform interested parties of research and to encourage discussion. The views expressed are those of the authors and not necessarily those of the U.S. Census Bureau. All results have been reviewed to ensure that no confidential information is disclosed, release authorization numbers CBDRB-FY19-CMS-7029, CBDRB-FY19-CMS-7227, CBDRB-FY19-CMS-7328 and CBDRB-FY19-CMS-7735. We would like to thank Abhay Aneja, Spencer Banzhaf, David Card, Conrad Miller, Jessie Shapiro, Joe Shapiro, Randall Walsh and seminar participants at the Chicago Federal Reserve, the Environmental Defense Fund, Gothenberg University, LISER, Rotterdam University, Stanford University, Tufts, UC Berkeley, the University of Chicago, the University of Hawaii, and the University of Illinois for helpful comments. Ellen Lin and Matthew Tarduno provided exceptionally helpful research assistance. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.