Mortality and healthcare services in Pennsylvania state prisons following extreme ambient temperatures.

Extreme temperatures pose severe risks for population health and healthcare systems. However, little research has examined implications for incarcerated populations, who may be particularly vulnerable given their limited control over their thermal environments. Here, we show that among people imprisoned in Pennsylvania (2000-2023), both warmer and cooler temperatures were significantly associated with higher rates of mortality, transfers to outside medical facilities and prison infirmary admissions, relative to outcome-specific reference minimum threshold temperatures. As temperature extremes become more frequent and severe, policy action including decarceration and the provision of accessible prison healthcare is urgently needed to protect the health of incarcerated populations.