Demographic disparities in United States Clean Air Act PM_2.5 attainment counties: assessing population living in nonattainment conditions

United States’ (US) declines in PM_2.5 concentrations attributed to the US Clean Air Act have overshadowed the geographic disparities in PM_2.5 exposure. Using PM_2.5 estimates formed by fusing a chemical transport model with satellite observations and calibrated to surface-level concentrations, we estimate census tract-level PM_2.5 concentrations in Clean Air Act compliant regions, administratively referred to as attainment counties. We then (a) estimate the total population living in census tracts that exceed the Clean Air Act attainment PM_2.5 concentrations and (b) identify the sociodemographic characteristics of each census tract by PM_2.5 concentration. We find that in 2020, there were an estimated 6.73 million individuals living in Clean Air Act PM_2.5 attainment counties located in census tracts that exceed Clean Air Act PM_2.5 attainment concentrations. Our findings also indicate that these census tracts with elevated PM_2.5 concentrations are disproportionately populated by Hispanic and foreign-born individuals.