Air conditioning in nursing homes linked with fewer deaths from extreme heat, Ontario study finds
Once considered a luxury, air conditioning has become an essential safeguard for nursing home residents. A new Ontario-based study published in JAMA Internal Medicine underscores the heightened mortality risk associated with extreme heat in nursing homes.
The population-based study was led by third-year University of Toronto (U of T) medical student Gabrielle Katz in collaboration with geriatrician and assistant professor Dr. Nathan Stall. The researchers found that residents of Ontario nursing homes without air conditioning were 8% more likely to die on extreme heat days than those with air conditioning.
The Ontario government mandated air conditioning in resident rooms for all nursing homes in 2021, increasing coverage from 45% to 99%. While previous research has shown that air conditioning reduces heat-related mortality in settings such as prisons and large urban centres, its protective effect in nursing homes has remained understudied.
Using a case-crossover design, the team analyzed 73,578 nursing home resident deaths in Ontario between June and September from 2010 to 2023. The analysis linked resident health data from the Ontario Ministries of Health and Long-Term Care with satellite-derived weather data from the North American Land Data Assimilation System.
Katz led the study’s conceptualization and design under the mentorship and supervision of Dr. Stall, working closely with U of T faculty members Drs. Kevin Brown and Vasily Giannakeas. In 2025, she received the Division of Geriatric Medicine at U of T's Summer Older Adult Research (SOAR) Experience Award to support this work.
Ontario remains the only Canadian province or territory to mandate air conditioning in nursing home resident rooms. Nationally, just 68% of Canadian households have air conditioning, with access lowest among renters, lower-income individuals, and those living in older homes.
“Our study also raises concerns for other vulnerable populations who do not have access to air conditioning,” says Katz.
Looking ahead, Katz and Dr. Stall plan to examine secondary outcomes, including hospitalizations and emergency department visits, as well as the role of medications known to impair heat regulation in older adults.
Katz, who received the Clinical Student Research Award at the 2025 Annual Scientific Meeting of the American Geriatrics Society for her work on this study, describes the project as deeply rewarding.
“As our population continues to age, I see a growing need for compassionate, skilled geriatricians, and I’m looking forward to the opportunity to contribute meaningfully to this area,” she says. “I also hope to continue engaging in research throughout my career as I believe it’s essential for improving the care of older adults.”