In Ontario and British Columbia, the summer that officially ended Monday was a scorcher: heat records fell in º£½ÇÉçÇø¹ÙÍøand Victoria, Barrie and Lytton.
Coroners for both provinces agree that such extreme heat can kill. But they disagree on how to track and report the death toll, leaving two of Canada’s biggest provinces with mismatching portraits of an escalating threat.
In B.C., chief coroner Dr. Jatinder (Taj) Baidwan has instructed doctors to refer all deaths that may be heat-related for further investigation. The B.C. Coroners Service reports a tally of these deaths annually. Its review of deaths during the 2021 heat dome is frequently cited by policymakers and researchers.
An analysis of 13Â years of critical injury data obtained by the Star shows heat poses a growing threat.
An analysis of 13Â years of critical injury data obtained by the Star shows heat poses a growing threat.
In Ontario, chief coroner Dr. Dirk Huyer has said it is neither scientifically valid nor logistically feasible to track deaths this way. The Office of the Chief Coroner, as a result, does not report a tally of heat-related deaths. Some legal and medical advocates have petitioned Huyer to adopt B.C.‘s approach since 2021.
The two chief coroners, who are friends, Baidwan said, “talk about this a lot. Whenever we meet, this comes up.”
Ontario is a different and bigger province, he added. But “nothing that Dirk has said to me would stop me thinking that I made the right decision … We found some facts that are now established that we wouldn’t have found otherwise.”
The federal government has declined to take sides. A spokesperson for Health Canada, asked whether the agency had concerns about inconsistencies in heat death reporting between two major jurisdictions, said that provinces have primary responsibility for health care and for this type of data collection.Â
But the spokesperson also pointed to , which found that while heat-related deaths have “increased noticeably” in the past decade, inconsistencies, potential under-reporting and data delays across the country have limited the creation of a “comprehensive national picture” of illness and death from heat.
Baidwan, who said he has fielded questions about B.C.‘s approach from representatives as far afield as the United Kingdom and Japan, added that Canada is not alone in grappling with how to tally heat’s death toll.
“This is a global phenomenon.”
Under Dr. Jatinder (Taj) Baidwan, chief coroner, the B.C. Coroners Service reports a tally of heat-related deaths annually: “We found some facts that are now established that we wouldn’t have found otherwise,” said Baidwan.
B.C. Coroners ServiceThe approach British Columbia takes today dates back to what the federal government calls the “deadliest weather event in Canada to date”: the 2021 western heat dome.
That week, Baidwan, then chief medical officer for the B.C. Coroners Service, issued a message to doctors and clinicians across the province. If heat “is considered in any way contributory to death,” he wrote, the case should be reported to the coroner’s service for review.
While the message read as a reminder, it actually represented a shift — and a nod to why heat is known as the “silent killer.”
During heat waves, epidemiologists can often point to spikes in mortality compared to how many deaths would have been expected over the same period without extreme temperatures. A dramatic example of this came Monday, when scientists in the journal Nature , the warmest year yet recorded globally.
But it can be hard to pinpoint which of these deaths in that period are the “extra” ones that occurred because of heat, and which would have happened anyway. Very few of those deaths are directly attributable to heatstroke or other forms of hyperthermia.
The body’s response to high temperatures — pumping blood toward the skin, sweating — puts stress on the heart, kidneys and other organs. For people already living with chronic illnesses, and for older people and others whose ability to dissipate heat is impaired, that stress is more likely to become lethal. As a result, many of the excess deaths during a heat wave are actually from heart attacks and other cardiovascular events, respiratory diseases and other seemingly unrelated conditions.
A heart attack in someone with cardiovascular disease would typically be coded as a natural death, without further review by a coroner. What Baidwan asked physicians to do instead was to refer all such deaths to his office, where, if heat was determined to be the condition that led to that death, they were classified as an accidental death, not a natural one.
“To me, it was a no-brainer,” Baidwan said. “But for the heat, they may have gone on … for another five years.”
Of the more than 800 deaths the service investigated, 619 were ultimately identified as being heat-related. An in-depth review published by the coroners service included information on where those people died, what socioeconomic conditions they lived in, and what chronic disease registries they belonged to, which would not have been possible to determine from a spike in excess deaths alone. The report has become an influential policy document, and surfaced some surprising information, including that almost all the deaths occurred indoors, in people’s homes.
In Ontario, within weeks of the heat dome, legal aid clinics, doctors and other advocates began writing to Huyer and Ontario’s coroners office to push to investigate heat deaths in the same way. Canada is warming twice as fast as the global average, they noted, and extreme heat is likely to extract an increasingly greater toll on vulnerable Ontarians.
Ontario’s chief coroner, Dr. Dirk Huyer, said it is neither feasible nor scientifically valid to attribute deaths from chronic conditions to extreme heat:Â “It is logistically not doable,” said Huyer.
Steve Russell º£½ÇÉçÇø¹ÙÍøStar File PhotoA coalition of advocacy groups this summer, but have not met with success.
“It is logistically not doable,” Huyer told the Star in a May interview, citing Ontario’s size as one reason. “And if it was doable, then what would we learn from this? We know that heat causes people to die.”
The knowledge we already have is enough to spur education and alerts to protect the public, Huyer said. But even if it wasn’t, “tracking would still not be accurate,” he added.
“There’s no scientific way to answer the question as to whether heat specifically led to the death, or whether they were going to get that cardiovascular illness for another reason.”
Baidwan rejects the idea that it’s unscientific to classify these deaths as heat-related, believing the opposite — that classifying them as a standard natural death would have missed the bigger picture.
Without investigation, these deaths “would have been totally lost, and you would not have been able to use them to actually really explore what had happened to us as a society, as a community, during that heat dome.”
Another surprising finding from the death investigations was that schizophrenia was associated with a higher risk of death than any other chronic disease, information that prompted doctors in Ontario to create a program to educate outreach teams supporting people with schizophrenia.
Baidwan says that Ontario’s system would not allow for this type of finding or the protective actions that flowed from it.
Huyer “has a different opinion, and he’s allowed to have a different opinion — that’s great. What I will say to you is, I believe that without doing the extra investigation, you do not get the granularity of data that allows you to make real science-based, evidence-based changes to your public policy.”
Over the two years following the 2021 heat dome, the B.C. Coroners Service reported another 27 suspected heat-related deaths. The data for summer 2025 is not yet available.
Glen Kenny’s work has upended assumptions about how the human body responds to extreme heat, but Ontario has not changed its rules in response to
Glen Kenny’s work has upended assumptions about how the human body responds to extreme heat, but Ontario has not changed its rules in response to
Baidwan said the coroners service may expand what it learned from investigating heat deaths to other environmental deaths.
“As the climate changes … can we do the right investigations, ask the right questions, pick up the right bits of data so we can see whether there are other deaths happening,” such as in flash floods?
“This has made us much more aware that the climate and how it acts around us is an important factor when it comes to death.”
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