Who is most at risk of death during a heat wave like Eastern Canada’s?

The heat wave battering Eastern and Central Canada this week has claimed the lives of as many as 17 people, all of whom officials say were either seniors or adults suffering from chronic illness.

The deaths are a reminder of how dangerous extreme heat can be for some segments of the populations.

The most vulnerable? According to health professionals, seniors and people with chronic illnesses like diabetes, heart disease or lung disease are the most at risk.

From a physiological perspective, older people are more at risk of feeling the health impacts of the heat due to a decreased sweat response, according to Dr. Allen Huang, Head of the Division of Geriatric Medicine at The Ottawa Hospital.

“They can’t produce as much sweat, and they don’t feel thirst as much. So they don’t hydrate themselves,” he said.  “So that puts them at a double risk for adapting to extra hot and humid conditions.”

Compounding the problem are any medications that lower blood pressure, which again affect sweat and thirst responses.

A prolonged heatwave like the one parts of the country are experiencing now adds to the problem, thanks to heat accumulation.

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“If you are in a hot apartment for a day, you may get uncomfortable, but generally we won’t see severe impacts,” said David Kaiser of Montreal’s public health department. “But if you were in a hot apartment for four days, at some point your body’s capacity to get rid of that heat is just overwhelmed.”

Of the 12 people who died in Montreal, Kaiser said none had air conditioning and the temperature inside their homes ranged between 33 and 46 degrees.

“At 46 degrees, you’re not going to last long,” said Kaiser.

Tweet This Click to share quote on Twitter: "At 46 degrees, you're not going to last long," said Kaiser.

But it goes beyond the medical, according to Kaiser.

“Heat is a social issue,” he said. “What we need to take seriously is making sure those people who are least able to take care of themselves are taken care of.”

Kaiser said officials know what heat does, who it affects and when it is coming.

“From a public health perspective, that gives us all the tools to try and prevent, to the extent possible, those impacts,” he said.

Immediate interventions include door-knocking or calling seniors, moving people to air conditioned places, and making sure people are hydrated.

But the response needs to last beyond the heatwave, according to Kaiser.

He says whether it’s heat, noise, traffic injuries or nutrition, it’s the same groups of people who are risk.

“From a public health perspective…the response is a response to a social problem. It’s a response to people who are systematically at risk. In the summer, it’s heat. In the winter, it’s cold,” Kaiser said. “In between, it’s the flu.”

Tweet This Click to share quote on Twitter: "From a public health perspective…the response is a response to a social problem. It's a response to people who are systematically at risk. In the summer, it's heat. In the winter, it's cold," Kaiser said. "In between, it's the flu."

Long-term solutions could including planting more trees in urban areas, making more air conditioned communal spaces in apartment building and creating social connections.

Those were helping some Ottawa seniors beat the heat at the city’s Good Companions Seniors’ Centre.  The city was Environment Canada’s hot spot on Wednesday afternoon, with temperatures hitting 34.2 C.

“I find it very restrictive because I have chronic obstructive pulmonary disease and this intense heat is very hard on my breathing,” said Patricia Moscrip. “One does feel a bit locked in.”

The air conditioned Ottawa seniors’ centre gave Moscrip an opportunity to get out in safe place. Although, it noticed a drop in participation this week as seniors decided to stay home rather than venture out in the heat.

Sandra Withers has the same disease. She said she doesn’t go outside in this weather because she can’t breathe.

“It feels like your throat is clogged,” she said. “I’ve been hiding at home since last Friday with my air conditioner.”

Now she’s just worried the power will go off before the heat subsides.

Environment Canada says a heat warning remains in effect for an area spanning southwestern and northeastern Ontario through southern Quebec and into the Atlantic region, with above normal temperatures and humid conditions likely to stick around into Thursday.

With files from The Canadian Press.