As heat waves intensify, new evidence from Ontario shows that resident-room air conditioning can mean the difference between life and death for nursing home residents.
Study: Air Conditioning in Nursing Homes and Mortality During Extreme Heat. Image credit: fizkes/Shutterstock.com
A recent study in JAMA Internal Medicine examined mortality rates during extreme heat days in Ontario nursing homes with air conditioning (AC) compared with those without AC, focusing on institutional long-term care settings.
A Growing Crisis for Older Adults
Older adults are more vulnerable to heat waves than young people. Heat-related deaths among seniors reached unprecedented levels in 2023, increasing by 167 % globally since the 1990s. This vulnerability stems from multiple factors, such as limited mobility, aging bodies regulating temperature less effectively, common medications affecting heat response, and social isolation compounding the risks.
A recent study has documented a global intensification of extreme heat. For instance, heat waves in the US have nearly doubled since the 1980s, underscoring a grim future for seniors. While air conditioning offers proven protection against heat-related illness, more than 35 million Americans lack it at home.
Given the health risks in extreme heat, not many studies have evaluated the importance of AC in nursing homes, where the majority of residents experience limited mobility, multiple chronic conditions, numerous medications, and cognitive impairment.
The regulatory landscape reveals troubling gaps. In the US, federal regulations require nursing homes initially certified after October 1, 1990, to maintain indoor temperatures within a specified range, but do not explicitly mandate air conditioning, and nearly half of the facilities were certified before that date. Prior to 2020, similar conditions prevailed in Ontario, with more than half of the province’s 600-plus nursing homes, housing over 76,000 residents, lacking air conditioning in resident rooms.
Before the mandate, homes without AC were required to provide designated cooled areas rather than room-level climate control. However, following the COVID-19 pandemic, Ontario announced a requirement for air conditioning in all resident rooms in July 2020, which took effect in June 2022, with compliance reaching 99.5 % of facilities by May 2023 at a cost of approximately CAD 200 million.
Heat-Related Deaths With and Without AC in Nursing Homes
The current study examines whether AC is associated with lower mortality among nursing home residents during extreme heat by comparing mortality rates on extreme heat days in facilities with and without resident-room climate control. A case-crossover analysis was conducted across 615 Ontario nursing homes between 2010 and 2023 during warm months (June–September), comparing mortality risk on extreme heat days in facilities with and without AC.
Extreme heat days were defined as those at or above the 90th percentile heat index for each facility’s location. Temperature and humidity data were collected from the North American Land Data Assimilation System. The current study included all Ontario nursing home residents who died between June and September in 2010–2023. The self-controlled design eliminated time-invariant confounding factors, such as sex, race, or location, that remained constant between death dates and matched control days set 14 days earlier.
For residents who died within 14 days of a hospital admission, the admission date was used as the case day; deaths occurring 14 or more days after admission were excluded. The selected residents must have resided in the same facility for at least 28 consecutive days prior to death. The current study examined the effect of heat waves on mortality, with or without AC, across three lag periods to capture acute and prolonged heat effects: lag 0–1 (death date plus 1 day prior), lag 0–3, and lag 0–6.
AC Installation Is Associated With Fewer Deaths During Heat Waves
The study analyzed 73,578 nursing home deaths in Ontario that occurred from June through September from 2010 to 2023. Approximately 68 % of the residents were 85 years or older, female (65 %), and living with dementia (70 %). The analysis included 40,255 deaths in facilities with air conditioning and 33,323 in facilities without it. Resident characteristics were similar across both facility types.
When Ontario announced its AC requirement in July 2020, 55 % of nursing homes lacked air conditioning. Facilities without AC tended to be for-profit, older, smaller, and more crowded than those with AC, and were more often located in higher-income communities. During the study period, nursing homes experienced an average of 14 extreme heat days per year, with heat index temperatures averaging 34.2°C on those days compared to 26.2°C across all summer days.
Extreme heat significantly increased mortality risk in nursing homes without AC but not in facilities with AC. Approximately 13.8 % of resident deaths occurred on extreme heat days in nursing homes without AC compared with 12.1 % in homes with AC. This association was strongest during the first three days after heat exposure. The effect of air conditioning was generally consistent across most resident subgroups, including those under 80 and over 90, males, residents with heart disease, and those in both low- and high-income areas, although some subgroup estimates were imprecise and not statistically significant.
The current study estimated that Ontario’s AC mandate was associated with approximately 33 fewer deaths on extreme heat days from 2020 to 2023, or about 10 deaths per year. Modeling suggested that had the mandate been implemented in 2010, it could have prevented 131 deaths over that decade, or about 13 deaths annually, assuming similar patterns of heat exposure and facility characteristics.
Conclusions
The current study highlighted that air conditioning is associated with lower mortality in nursing homes during extreme heat, but does not eliminate heat-related risk entirely. Facilities without AC had higher mortality on days with extremely high temperatures, with Ontario’s mandate linked to an estimated 10 fewer deaths annually.
As heat waves intensify globally, these findings carry urgent policy implications. Universal air conditioning mandates should extend beyond nursing homes to all congregate care settings that house vulnerable populations, including assisted living facilities, group homes, prisons, and psychiatric institutions, while recognizing that these findings are specific to institutional care environments.
As summers grow hotter, protecting vulnerable residents in institutional settings represents both a public health imperative and a fundamental measure of how societies care for their most at-risk members.
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