About 670 people in major Canadian cities lost their lives due to extreme heat days in Canada from 2000 to 2021, according to a new study from Statistics Canada. The study looked at 12 cities with populations of more than 500,000: Toronto, Montreal, Calgary, Ottawa, Edmonton, Winnipeg, Mississauga, Vancouver, Brampton, Hamilton, Surrey and Quebec. These cities represent 34% of the country’s population.
“In the 12 cities, approximately 670 excess non-accidental deaths, 115 excess deaths caused by cardiovascular causes, and 115 excess deaths caused by respiratory causes were attributable to extreme heat events during the study period,” notes the document. For Montreal, an extreme heat event represents two consecutive days where it is 32˚C degrees or more, or one day where the humidity is more than 40.
Didier Garriguet, a scientific editor at Statistics Canada, reports that the risk of non-accidental mortality is 9% higher for all age groups during extreme heat days. “We see that people aged 65 and over are a little more at risk, due to heat stroke, or more often indirect causes, such as having an underlying disease that is aggravated by extreme heat,” he says. Garriguet expects heat-related deaths to increase in the coming years. “We had an average of 3.5 days of extreme heat per year in the period studied, and I think we’re already at more than 3 days this year, and it’s only June. So, yes, we anticipate an increase.”
Montreal reported an excess mortality of non-accidental origin of 295 from 2000 to 2020, compared to 250 in Toronto and 32 in Quebec. This is because extreme heat does not affect everyone equally. “In general, mortality risks during extreme heat events were higher in cities with greater proportions of renting households,” the study notes. This is particularly the case in Montreal and Toronto, where respectively 61% and 48% of households are renters. “People living in rental housing are much less likely to have air conditioning compared to provincial averages,” the researchers note.
Furthermore, in another study on the issue, a team from the National Institute of Scientific Research demonstrated that every summer, in Quebec, high temperatures are associated with 470 deaths, 225 hospitalizations, 36,000 emergency room visits, 7,200 ambulance transport and 15,000 calls to Info-Santé. This health burden was especially concentrated during the 5% of the hottest days of the summer, with nearly 200 deaths, 170 hospitalizations, 6,200 emergency room visits, 1,500 ambulance transports and 3,300 calls to Info-Santé, according to the study. published in the scientific journal Environmental Research.
