The Current

After deadly 2018 heatwave, Montreal scientists are working on science of keeping cool

We visit a heat lab in Montreal, where scientists are testing the tricks we all use to keep cool. They're looking for the science behind how we cope when the mercury is rising.

Study puts volunteers in a small, hot room and measures how their bodies react

Marie Nguele and Georgia Chaseling get Michel Dupuis, 74, ready to enter the 'climate chamber,' where he will undergo tests to see how our bodies cope in extreme heat. (Alison Northcott/CBC)

Full Episode Transcript

In a Montreal laboratory, scientists are running tests in a hot little room called a "climate chamber" to learn more about how we cope when the mercury is rising. 

"It's set to 38 degrees and 60 per cent relative humidity," said Georgia Chaseling, a physiologist at the EPIC Centre of the Montreal Heart Institute.

"You can really feel the heat seeping outside of the chamber. Like, the laboratory right now feels really humid and hot as soon as you walk in," she said.


Chaseling and her team are putting volunteers into that hot room and measuring how their bodies react. They're looking for what they call "practical and economical strategies for cooling people off in extreme heat."

Participants are hooked up to sensors that measure vital signs while they sit in the climate chamber. They also give fluid samples, and record how much weight they lose from sweating over a three-hour trial (up to 1.4 kilograms).

The study focus is on one high-risk group: people over 50, with heart conditions.

Last summer, 66 people died during a heat wave in Montreal. Around two thirds of those deaths were seniors with underlying health conditions — a statistic that was recorded because Quebec is the only Canadian province that records heat as a cause of death.

The Current's Susan McKenzie spent an hour in the climate chamber, to see the work the scientists are doing. Here's part of what she learned. 

Oscillating fans may not be the solution in a dry heat. (Ben Bryant/Shutterstock)

Fans can make you hotter

"Evaporation of our sweat is our main avenue to lose heat from the body, and keep our core temperature regulated," said Chaseling.

But she warned that "once you reach about 60 years or over, you have less of an ability to produce sweat."

That means older people have a greater risk of heat stroke or "heat stress," she said.

For seniors trying to stay cool, Chaseling explained that the type of heat is also important.

It's almost like being in a convection oven, where you're just heating up faster and faster.- Georgia Chaseling

Your sweat won't evaporate as easily in humid environment, as there is already a lot of moisture in the air. Sitting in the breeze of a fan can help, because it cools the skin, but also helps your sweat to evaporate.

But in dry heat, a fan can actually makes things worse, particularly for seniors.

"If it's really, really hot and you put a fan on someone who already can't sweat in a really dry environment, then you're just blowing hot air onto them," she said.

"It's almost like being in a convection oven, where you're just heating up faster and faster."

To sum up: fans are good at cooling us off in humid heat, but they can make us hotter in dry heat.

Susan McKenzie spent an hour in the climate chamber, to see the work the scientists are doing up close (and sweaty). (Susan McKenzie/CBC)

Cold drinks don't do much (but they feel nice)

A cold drink may seem like heaven on a hellishly hot day, but it might not be doing much, Chaseling said.

"The cold water, when it enters your body, it activates receptors that send the signal to your brain saying: 'Hey I've just felt something cool. This feels really good,'" she said.

But your body will just as quickly warm that fluid up to match your temperature, she explained.

"Physiologically, [the cold drink is] not going to do anything to your core or skin temperature. But it makes you feel cool, and I think that's a really important thing during the heat wave," she said.

What works better is cooling the skin.

Whether it's a cold shower, spraying yourself with cold water, or wetting your skin with cold towels, you should "do something that is actively trying to keep your skin cool, and keep yourself cool," she said.

Left to right: Daniel Gagnon, Michelle Jacobs, and Georgia Chaseling were among the researchers involved in the project. (Susan McKenzie/CBC)

Chaseling warned that if you are dehydrated, a sugary drink can make it worse. She cited a study that suggested they might worsen rather than benefit dehydration, and lead to kidney problems.

"Water [is] probably the best thing to have," she said.

Air conditioning? It's complicated

Air conditioning may solve heat waves problems for a lot of people, but Daniel Gagnon warned it can come with complications.

"Air conditioners ... basically take out the hot air and push it outside," said Gagnon, an assistant professor in the department of pharmacology and physiology at the Université de Montreal. 

A woman cools off in a water fountain in Marseille, France as a heatwave hits much of the country on June 28, 2019. (Jean-Paul Pelissier/Reuters)

"When you do that with big buildings, or a lot of buildings, they can actually heat up the air outside, so it can make the heat wave worse."

He added that the energy used to power them might be contributing to "the climate changes that are leading to more and more intense heat waves," and noted that not everyone has the facility, or can afford to run it if they do.

Check in on seniors

If air conditioning isn't available at home, find a place where it is, such as a shopping mall or movie theatre. You should also avoid strenuous activity during the sun's peak hours.

Chaseling said that seniors, or people with medical conditions, should stay in touch with loved ones during hot times.

"It's really important to contact a family member or a friend and let them know that you're okay, and just making sure that you're not alone during that time."

Click 'listen' near the top of this page to hear the full conversation.

Written by Padraig Moran. Produced by Susan McKenzie.


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