Air Pollution and Mortality: Non-Attainment of PM_2.5 National Ambient Air Quality Standards

Using national regulatory data and estimated fine particulate matter (PM_2.5) concentrations at the county level, we exploit exogenous variation in PM_2.5 exposure induced by the PM_2.5 National Ambient Air Quality Standards (NAAQS) within an instrumental variables model to measure the effect of pollution on non-accidental mortality rates. We find that a 10 μg/m³ increase in PM_2.5 leads to 11.4% and 13.1% increases in adult and senior mortality rates, respectively. Furthermore, we use event study specifications and difference-in-differences models and find that the PM_2.5 NAAQS led to significant reductions in PM_2.5 concentrations within regulated counties, along with some evidence for significant reductions in county-level mortality rates as a result of regulation in the decade following the implementation of the standards. We estimate that the implementation of the 1997 PM_2.5 NAAQS led to an approximate reduction of 1% in non-accidental adult mortality rates among treated counties in the period from 2005-2015, and counterfactual analysis suggests large potential benefits from further lowering the regulatory threshold.

Keywords: Fine particulate matter, environmental policy, mortality, air pollution

JEL Codes: I18, Q51, Q53, Q58