Ontario’s Chief Coroner says there have been three deaths in the province that may have been related to last week’s stifling heat.

The deaths were reported to the coroner’s office over the last four days, Dr. Dirk Huyer said at a news conference on Tuesday, and are still being investigated. Death investigations can take weeks, or sometimes months, to complete.

The number of possible heat-related deaths reported by Huyer is significantly lower than those reported in Quebec. Health authorities in that province have said up to 70 people have died from heat-related incidents over the past month.

Huyer said the difference in numbers stems from the fact that the coroner’s office in Ontario only receives notifications for deaths that are labelled as accidental or abnormal. Natural deaths, or those in which prior medical conditions could have been impacted by factors such as temperature, are not reported.

“The deaths we investigate are deaths that are more typically accidental and so they would be situations of heat stroke when someone dies from the direct effect of heat,” he said.

Other public health jurisdictions look at the potential contribution of heat or cold as a contributing factor in death, but Ontario does not, Huyer said.

“We do not, at the Office of the Chief Coroner, capture those specific deaths because most are not reported to us. They would be cases recognized specifically as natural and would not be investigated.”

Despite that fact, Huyer noted that a study conducted in 2016 showed that every five degree increase in temperature was associated with a 2.5 per cent increase in non-accidental deaths.

When asked how this statistic correlates with the number of reported heat-related deaths in Ontario, Huyer said the coroner’s office was governed by legislation that doesn’t allow for that kind of reporting.

“It’s not a justification. Right now we have mandatory reporting criteria that flows from legislation we work with.”

Ontario’s Chief Medical Officer Dr. David Williams said he is concerned about these heat waves and how they could impact the most vulnerable population.

“I’m concerned that as we deal with changing climate, if the frequency of the heat alerts increases and the length and severity of it increases, how will our current system adapt and respond to those extra stresses?”

Williams said that Ontario hospitals saw an increase in admissions and emergency visits for heat-related symptoms like sunburns, dehydration and hyperthermia.

“We did okay,” he said. “It’s no time to sit down and do nothing.”

Southern Ontario and most of the Greater Toronto Area was struck with a severe heat wave that began at the end of June. Environment Canada issued a number of weather warnings, saying that temperature, with humidex, could feel like it was in the mid-40s.

The heat warning was lifted on July 6.