Extreme Temperatures, Elevated PM2.5, and Acute Care Events Among Dual-Eligible Nursing Facility Residents.

BACKGROUND: Extreme temperatures and elevated fine particulate matter (PM2.5; particles 2.5 μm or less) pose serious health risks for older adults. Nursing facility residents may be especially susceptible because they have complex health needs and limited ability to self-protect, and because nursing facility construction and HVAC capacity can be insufficient to buffer indoor environments from outdoor extremes. Yet, nursing facility regulations address only indoor temperature with no comparable standards for indoor air quality, including PM2.5. We assessed whether outdoor extreme heat, extreme cold, and elevated PM2.5 were associated with emergency department (ED) visits and hospitalizations among nursing facility residents. METHODS: Using 2017-2020 Medicare and Medicaid claims linked to daily weather data, we conducted longitudinal analyses with nursing facility fixed effects to estimate associations between extreme heat, extreme cold, and elevated PM2.5 (PM2.5 > 9 μg/m3) and all-cause ED visits and hospitalizations among dual-eligible nursing facility residents aged 65 years and older. RESULTS: The sample included 24,784,081 nursing facility-days from 24,760 facilities across 47 states and Washington, DC. Extreme temperature and elevated PM2.5 were associated with increased acute care utilization. On extreme heat days, ED visits and hospitalizations increased by 0.022 (95% CI, 0.003-0.041) and 0.025 (95% CI, 0.011-0.039) per 1000 resident-days, respectively. On elevated PM2.5 days, corresponding increases were 0.020 (95% CI, 0.013-0.027) and 0.017 (95% CI, 0.012-0.022) per 1000 resident-days. Extreme cold was also associated with an increase in hospitalizations of 0.014 per 1000 resident-days (95% CI, 0.001-0.027). CONCLUSIONS: Among nursing facility residents, acute care events increased on extreme temperature days despite the existing indoor temperature regulations. Acute care events also increased on elevated PM2.5 days. These findings suggest that environmental exposures contributed to acute care utilization among nursing facility residents.