Background/Aim: Many epidemiological studies have consistently reported positive associations between long-term exposure to fine particulate matter (PM2.5) and risk of mortality. However, research on which residential environmental and social factors modify the effect of long-term exposure to air pollution on mortality risk is limited. In this study, we evaluated residential greenness and several individual- and community-level factors as effect modifier for long-term exposure to PM2.5 and risk of mortality.Methods: We used data from all Medicare beneficiaries in NC and MI (2001-2016). Annual averages of PM2.5 were estimated using spatio-temporal prediction models to assign zip-code level exposures based on the residence for each enrollee. We estimated the risk of death associated with a 1 µg/m3 increase in PM2.5 using a Cox proportional hazards model that controlled for demographic characteristics, Medicaid eligibility, and area-level covariates. We assessed health disparities by residential greenness using the Normalized Difference Vegetation Index (NDVI) and several individual- and community-level factors (e.g., race, socioeconomic status, urbanicity). We considered combined disparities (e.g., race and SES, urban green vs. rural green) and compared regional characteristics, exposure levels and thus effect estimates between MI and NC.Results: PM2.5 exposure was significantly associated with increased risk of non-accidental mortality for NC and MI. The hazard ratio (HR) for death was 1.124 (95% confidence interval (CI) 1.117, 1.130) and 1.007 (95% CI 1.001, 1.013) for NC and MI, respectively. Our preliminary analysis showed that higher risk of PM2.5 exposure on non-accidental mortality was associated with some factors such as residential greenness, urbanicity and socioeconomic status. The HR was higher in areas with less green space and in areas with lower SES, with different patterns of effects by urbanicity and region.Conclusions: Our findings indicate that the multiple aspects of disparity factors may affect disproportionate mortality burdens from air pollution exposures.