Breathing Unequal Air: PM2.5 Exposure and Life Expectancy Inequities Across U.S. Neighborhoods

Air pollution is a leading environmental determinant of health, yet few studies have assessed how long-term exposure to fine particulate matter (PM2.5) at the neighborhood level relates to life expectancy, a key indicator of population health and well-being. We conducted a nationwide ecological analysis of 66,717 U.S. census tracts to evaluate the association between average PM2.5 concentrations (2011–2014) and life expectancy at birth (2010–2015). PM2.5 estimates were derived from the Environmental Protection Agency’s Downscaler model, and sociodemographic covariates, including poverty, income, education, insurance coverage, housing conditions, and racial composition, were obtained from the American Community Survey. In unadjusted models, each 1 microgram per cubic meter (µg/m3) increase in PM2.5 was associated with a 0.23-year reduction in life expectancy. After adjusting for tract-level sociodemographic characteristics using multivariable linear regression, the association persisted at 0.19 years (p < 0.001). Interaction models revealed that this negative association was significantly stronger in tracts with higher proportions of Black residents, indicating a disproportionate burden among structurally marginalized communities. These findings suggest that air pollution contributes meaningfully to spatial inequities in life expectancy in the United States. By integrating environmental exposure data with neighborhood sociodemographic conditions, this study highlights the intersection of place, pollution, and structural disadvantage. Public health and environmental policy efforts should address not only overall reductions in air pollution but also its uneven distribution across communities. Understanding how place-based exposures reinforce existing social and racial inequities is critical to advancing health equity.