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Ontario’s chief coroner says his province’s method of tracking heat-related deaths – which takes longer and includes a narrower definition than one used in Quebec – is a more useful way of assessing the dangers of soaring temperatures.

Dr. Dirk Huyer revealed on Tuesday that his office is investigating three deaths related to last week’s heat wave in Ontario. This comes after health authorities in Quebec revealed 74 people died when a suffocating heat wave rolled over the southern part of that province.

The two provinces have different ways of investigating heat-related deaths. The Ontario coroner’s office only looks at “accidental deaths” where they believe heat was the direct cause of death – such as heat stroke and hyperthermia – as “heat-related”. Quebec tends to investigate more deaths that occur during a heat wave, including ones where it appears the person suffered from a chronic condition such as high blood pressure or lung disease, and the heat exacerbated their condition.

Dr. Huyer said that assessing whether heat caused a death can be “very, very difficult,” as a result of the large number of factors that can affect a person’s health. He added that tracking the number of dead is less useful than accounting for other factors, such as hospital visits and cases of dehydration and heat exhaustion.

“Understanding the changes of health-care usage through the emergency department and increased issues ... would be far more informative than would be the number of deaths,” he said. “Deaths are really not a good measure, from a real-time point of view, to understand a health problem.”

Quebec’s chief coroner, Pascale Descary, said she was hesitant to judge which method was better, but “in a context like this one, I think it’s preferable to investigate maybe more than less to make sure to document the situation [correctly]. And if certain numbers of those deaths [turn out not to be] heat-related, we just have to conclude that it’s a natural death,” she said.

It’s important to document how many deaths were heat-related, Ms. Descary said, “so we will be able, at the end of our investigation, to formulate recommendations to different organizations, or the minister, to protect la vie humaine the human life. That’s our main goal.”

Emergency-room visits for heat-related illnesses in Ontario went up “significantly” from June 29 to July 7, said Dr. David Williams, the province’s Chief Medical Officer of Health.

“There was significant morbidity related to [heat], and some happened fairly quickly at the start of the heat wave and it persisted throughout,” he said.

Dr. Huyer said he doesn’t know whether the number of potentially heat-related deaths in Ontario will rise.

“We are hoping that ... all the efforts that are being undertaken through the heat warnings and through the work of the public health agencies would help to ensure that we don’t have additional deaths, but I can’t predict,” he said.

The investigations into the three deaths – which include evaluations of the scenes, information collected from physicians and family members, autopsies and potentially two rounds of sample tests – will take weeks to months, Dr. Huyer said.

“Each investigation is unique in and of itself,” he said. “We want to get the highest-quality and the best answers possible for the family members, the community, for public health efforts, as well as many other reasons.”

Dr. Huyer did not comment on where the deaths took place because of the potential of identifying the victims.

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