Long-term PM2.5 exposure and mental health disparities: A prospective analysis of the All of Us Research Program.

Despite known environmental inequities, the impact of air pollution on mental health across diverse populations remains uncharacterized, with prior research limited largely to cross-sectional studies or homogeneous cohorts. In this paper we evaluated associations between long-term fine particulate matter (PM) exposure and incident depression and anxiety in a large, diverse cohort and investigated effect modification by race/ethnicity, insurance status, and neighborhood-level socioeconomic status. We used data from the All of Us Research Program (2018-2022) to analyze two cohorts (n > 100,000 each) to identify incident cases of depression and anxiety. We assigned annual average PM concentrations based on residential zip-codes and used Cox proportional hazards models with natural cubic splines to estimate associations, adjusting for individual and community-level covariates. For a 10-μg/m3 increase in PM, the hazard ratio (HR) was 2.14 (95 % CI: 1.41, 3.24) for anxiety and 1.66 (95 % CI: 1.02, 2.70) for depression. Comparing highest to lowest PM quartile, the HR was 1.10 (95 % CI: 1.03-1.19) for anxiety and 1.45 (95 % CI: 1.33-1.57) for depression. Depression risks were elevated even at PM levels below the EPA standard of 9.0 μg/m, while anxiety risks increased only at higher concentrations. Black participants showed approximately twice the risk of both outcomes compared to other racial groups, which may reflect the cumulative impacts of systemic racism in the United States, including residential segregation, limited healthcare access, and chronic stress. Results emphasize the need for targeted interventions in communities facing multiple structural disadvantages.