Air quality related equity implications of U.S. decarbonization policy.

Climate policies that target greenhouse gas emissions can improve air quality by reducing co-emitted air pollutant emissions. However, the extent to which climate policy could contribute to the targets of reducing existing pollution disparities across different populations remains largely unknown. We quantify potential air pollution exposure reductions under U.S. federal carbon policy, considering implications of resulting health benefits for exposure disparities across U.S. racial/ethnic groups. We focus on policy cases that achieve reductions of 40-60% in 2030 economy-wide carbon dioxide (CO 2 ) emissions, when compared with 2005 emissions. The 50% CO 2 reduction policy case reduces average fine particulate matter (PM 2.5 ) exposure across racial/ethnic groups, with greatest benefit for non-Hispanic Black (-0.44 μg/m 3 ) and white populations (-0.37 μg/m 3 ). The average exposure disparity for racial/ethnic minorities rises from 12.4% to 13.1%. Applying an optimization approach to multiple emissions reduction scenarios, we find that no alternate combination of reductions from different CO 2 sources would substantially mitigate exposure disparities. Results suggest that CO 2 -based strategies for this range of reductions are insufficient for fully mitigating PM 2.5 exposure disparities between white and racial/ethnic minority populations; addressing disparities may require larger-scale structural changes.