Differences in Long Term Exposure to Wildfire Smoke Among People Who Are Incarcerated Compared to People Who Are Not Incarcerated in California, 2015-2020

Kristen N Cowan; Lawrence S Engel; Lauren Brinkley-Rubinstein; Sara N Levintow; Shabbar I Ranapurwala; Paul Delamater

doi:10.1029/2025GH001569

Differences in Long Term Exposure to Wildfire Smoke Among People Who Are Incarcerated Compared to People Who Are Not Incarcerated in California, 2015-2020

Geohealth. 2026 Apr 3;10(4):e2025GH001569. doi: 10.1029/2025GH001569. eCollection 2026 Apr.

Authors

Kristen N Cowan^{1

2}, Lawrence S Engel¹, Lauren Brinkley-Rubinstein³, Sara N Levintow¹, Shabbar I Ranapurwala¹, Paul Delamater⁴

Affiliations

¹ Department of Epidemiology Gillings School of Global Public Health University of North Carolina at Chapel Hill Chapel Hill NC USA.
² Department of Epidemiology and Environmental Health School of Public Health and Health Professions University at Buffalo Buffalo NY USA.
³ Department of Population Health Sciences School of Medicine Duke University Durham NC USA.
⁴ Department of Geography University of North Carolina at Chapel Hill Chapel Hill NC USA.

Abstract

Wildfire smoke exposure is associated with a range of adverse health outcomes. People who are incarcerated may be especially vulnerable to smoke exposure because, compared to non-incarcerated people, they lack agency to control their exposure. The goal of this study, within California, is to (a) geographically characterize wildfire-attributable PM_2.5 exposure from 2015 to 2020 and (b) to determine whether the burden of wildfire PM_2.5 exposure is higher in neighborhoods that contain carceral facilities compared to neighborhoods without carceral facilities. Data on wildfire-attributable PM_2.5 was linked to census-tract level counts of incarcerated and non-incarcerated populations. Statewide statistics on wildfire-attributable PM_2.5 were calculated for five exposure metrics: (a) number of weeks with wildfire PM_2.5 > 5 μg/m³, (b) number of days with non-zero wildfire PM_2.5, (c) mean daily wildfire PM_2.5 during the peak exposure week, (d) number of smoke waves (defined as ≥2 consecutive days with >15 μg/m³ wildfire PM_2.5), and (e) average of the annual mean wildfire PM_2.5 concentrations. To spatially compare wildfire PM_2.5 exposure among incarcerated people to non-incarcerated neighbors, population-weighted exposure metrics were calculated for each tract containing incarcerated people and compared to surrounding tracts' exposures using non-incarcerated population weights. Across California, census tracts containing incarcerated people had heightened wildfire-attributable PM_2.5 exposures and a large proportion of California's incarcerated population (48.5%) resided in tracts in the highest quartile of non-zero wildfire PM_2.5 days compared to non-incarcerated people (25.9%). Prisons and jails in areas that have high wildfire smoke exposure levels should improve ventilation capabilities, provide protective equipment and develop preparedness plans.

Keywords: air pollution; disparities; spatial epidemiology; wildfire.

Plain language summary

Wildfire smoke exposure is associated with a range of adverse health outcomes. People who are incarcerated may be especially vulnerable to smoke exposure because, compared to non‐incarcerated people, they do not have the ability to make behavioral changes like wearing a mask or reducing time outside to minimize their exposure. One way to quantify wildfire smoke exposure is to measure wildfire‐attributable PM_2.5. In this study, we geographically examined wildfire‐attributable PM_2.5 from 2015 to 2020 in California and determined differences in exposure comparing incarcerated people to non‐incarcerated people. To examine the frequency, intensity and duration of wildfire smoke exposure, five metrics of wildfire smoke exposure were created across the state, including the measure number of days with non‐zero wildfire PM_2.5. Across California, incarcerated people were almost two times as likely (48.5%) as non‐incarcerated people (25.9%) to live in the highest quartile of the exposure metric number of non‐zero wildfire PM_2.5 days. Because people who are incarcerated have limited ability to protect themselves from smoke exposure when wildfires occur, this study demonstrates the need to prioritize this population in studies on the health effects of wildfire smoke exposure and to develop plans to protect people who are incarcerated from wildfire smoke exposure.