Air conditioning may prevent heat-related deaths among seniors

In nursing homes, air conditioning (AC) helps lower mortality among older adults on days when the heat index is extremely high, according to a case-crossover study in Canada.

Researchers looked at 73,578 deaths that occurred during the warm months (June to September) among nursing home residents between 2010 to 2023. They estimated the odds of all-cause mortality during extreme head days and compared them between nursing homes with and without AC. An extreme heat day was defined as any day in the ≥90th percentile of the heat index (ambient temperature and relative humidity) during the study period.

Of the deaths recorded, 40,255 (mean age 86.8 years, 65.6 percent female) occurred at 276 homes with AC and 33,323 (mean age 87.2 years, 64.8 percent female) occurred at 339 homes without AC. Prior to the announcement of the AC mandate in July 2020, nursing homes without AC (55.1 percent) were predominantly investor owned (ie, for profit), were built to older design standards, and had more residents per room compared with nursing homes with AC.

A total of 4,889 deaths in nursing homes without AC and 4,611 deaths in nursing homes with AC occurred on extreme heat days (13.8 percent vs 12.1 percent). Extreme heat was associated with 11-percent greater odds of mortality in nursing homes without AC (odds ratio [OR], 1.11, 95 percent confidence interval [CI], 1.06–1.16) but not in nursing homes with AC (OR, 1.03, 95 percent CI, 0.98–1.07).

Nursing homes without AC were associated with greater odds of mortality on extreme heat days compared with nursing homes with AC (relative OR, 1.08, 95 percent CI, 1.01–1.15). Lagged analyses indicated the associated effects of extreme heat persisted for 3 days beyond the initial exposure.

These findings highlight the importance of AC provision in nursing homes and other congregate care settings to reduce the risk of mortality among older adults during extreme heat days.