Extreme heat: Caring for our most vulnerable

August 9, 2023


As the impacts of climate change increase in Canada, we expect to experience more and more days of extreme heat. Even though most people are able to cope with this rise in temperatures over the summer months, extreme heat can have a devastating impact on some of those who are most susceptible to experiencing adverse health impacts.

The unprecedented eight-day heat dome in 2021 broke the Canadian national temperature record three days in a row, with the highest temperature ever recorded in Lytton, BC (49.6 °C). As a result of this heat dome, 619 people in British Columbia died from exposure to extreme heat, despite best efforts from health authorities.

In BC, 98% of these deaths occurred indoors, 67% were over 70 years of age and 33% lived in neighbourhoods that were most socially deprived. Heat-related deaths were also higher among people with specific chronic diseases (such as schizophrenia and kidney disease).

Melissa Gorman, Health Canada’s Senior Science Advisor for the Extreme Heat Program, and her team are committed to working with health partners to better prepare for future extreme heat events. The research is now zeroing in on some of the groups that are most susceptible to experiencing health effects from exposure to extreme heat: older adults, pregnant women, children, those with chronic diseases and people with mental health issues, particularly those living with schizophrenia.

“We know that people diagnosed with schizophrenia are disproportionately affected. We want to know why and what we can do to protect these populations during future heat events,” says Melissa.

While people with a history of schizophrenia represent only about 1% of the Canadian population, a recent study by colleagues at the BC Centre for Disease Control, with support from Health Canada, found that they represented more than 8% of all people who died during the 2021 heat dome. The study found that mental illnesses were among the conditions that left people most susceptible to death, with those with schizophrenia at the highest risk. Researchers are trying to understand what makes them especially vulnerable to extreme heat.

Schizophrenia affects the way a person interacts with and understands the world. While the exact reason why people with schizophrenia were disproportionately impacted during the heat dome is not yet clear, we do know it can impact a person’s ability to perceive that they are overheating and recognize the need to take action. Some medications can also impact the body’s ability to regulate its own temperature. Schizophrenia may also lead to social isolation which is a risk factor for death during extreme heat. Those are all avenues to explore in future studies.

“Altogether, we don’t really know why people with schizophrenia are more at risk from extreme heat. We, in support of health partners and researchers, are trying to better understand the reasons for their increased vulnerability to develop better interventions or policies to help them in the future,” explains Melissa.

It’s important to remember that extreme heat can pose a risk to everyone. It can lead to dangerous indoor temperatures in homes without air conditioning. The best way to ensure your loved ones are safe is to make plans ahead of time to check in on them regularly and to know how to recognize the signs of heat-related illness. Make sure they understand the risks and have a way to stay cool.

“Even if you don’t consider yourself a part of a heat-vulnerable population, it doesn’t mean you aren’t at risk! You need to be prepared for extreme heat anyway,” cautions Melissa. “Extreme heat is a silent killer and everyone is at risk.”

In the meantime, researchers continue to look at the reasons that make some people more vulnerable to the effects of extreme heat.

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