New Research about Health Impacts of Heat and Air Quality

The planet experienced the hottest day on record earlier this month and climate projections estimate the intensity of heat waves and poor air quality will increase and continue to cause severe impacts. Researchers from the University of Waterloo and Toronto Metropolitan University have refined and expanded a method of data collection to assess their health impacts.

They discovered that even moderate temperature increases can lead to increased hospital visits and death for older adults and those with cardiorespiratory conditions.

The new method will help municipalities make a strong case for choosing which mitigation and adaptation measures to pursue to effectively respond to climate changes..

“Heat waves cause more deaths in Canada than any other climate hazard,” said Dr. Mohamed Dardir. “We are getting better at being proactive and planning for climate emergencies, but we still aren’t responding to temperatures in the same way we respond to big weather events, such as floods and fires.”

The study analyzed the spring and summer in Mississauga and Brampton, Ontario. By integrating data on air quality and heat, the researchers achieved the most detailed picture of the short-term health risks impacting the vulnerable population on a municipal level. The findings confirm there was an increase in the total deaths and hospital visits in these areas with the highest impact happening on the day of the heat and poor air quality and extending two days after these events.

In the future, the team plans to expand their analysis to include more environmental hazards, such as storms and floods, and factors including ambulatory calls across municipalities in Ontario and other provinces. The researchers say that this work will help civil society and policy makers grasp the magnitude of these climate events and equip decision makers to justify investments in climate resiliency.


Mohamed Dardir, Jeffrey Wilson, Umberto Berardi. Heat and air quality related cause-based elderly mortalities and emergency visits. Environmental Research, 2023; 216: 114640 DOI: 10.1016/j.envres.2022.114640

University of Waterloo. “New research method determines health impacts of heat and air quality: Even moderate temperature increases can cause more emergency hospital visits and deaths.” ScienceDaily. ScienceDaily, 27 July 2023. <>.

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Photo by Wolfgang Hasselman