Spatial Pattern of Outdoor PM _2.5 Air Pollution in U.S. Prison Landscapes from 1998 to 2022

Exposure to fine particulate matter (PM_2.5) is associated with the development of diseases and premature death. However, little is known about the potential PM_2.5 exposure of incarcerated populations. In this paper, we used satellite-derived data to assess outdoor PM_2.5 concentrations at 1,593 prisons in the contiguous U.S. from 1998 to 2022. Across our study period, despite overall national decreases in PM_2.5 concentrations and disparities, prisons on average experienced higher pollution than the nonincarcerated U.S. population. In 2022, over 500 prisons had spatially averaged concentrations higher than the population-weighted concentrations of their home states. We also found evidence that in 12 states, state and federal prison populations systematically had higher PM_2.5 than the nonincarcerated populations in those states; similar findings were obtained for national analyses stratified by degree of urbanicity. In 2022, about 7% of prisons were above federal air quality standards, with over 50% of these prisons located in California. Collectively, the contributions of this study in finding health-relevant disparities in outdoor PM_2.5 concentrations for prisons across several different metrics may highlight an urgent public health crisis that requires deeper inquiry and interventions from government officials. Decarceration would work to immediately reduce the population of people vulnerable to air pollution in prisons.