Heat stroke vs. heat exhaustion: What risks Canadians should know as temperatures rise

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Contact a qualified medical professional before engaging in any physical activity, or making any changes to your diet, medication or lifestyle.

As Canada braces for an unusually intense May heat wave, experts and health officials are sounding the alarm about the risks of heat stroke and heat exhaustion. In May, several provinces including British Columbia, Quebec and Ontario, saw temperatures above seasonal norms, raising concerns about safety.

The heat wave was already accompanied by several wildfires in Alberta and British Columbia, exacerbating air quality issues and the impacts of smoke. But heat can have an impact too. As we roll into summer and temperatures climb, experts caution people to understand the risks hot weather brings.

"I think people have to realize that heat is a silent killer," said Glen Kenny, a professor at the University of Ottawa and director of the Human and Environmental Physiology Research Unit, previously told Yahoo Canada.

Considering the climate, experts say heat stroke and heat exhaustion will be common during the summer months. Read on to learn the risks, symptoms and how to spot the difference between these two conditions.

Heat stroke vs. heat exhaustion: What’s the difference?

According to Health Canada, heat exhaustion occurs when your body overheats but is unable to cool itself down. For example, you can overheat while performing physical activity — especially when it’s hot and humid outside. Heat exhaustion symptoms include headache, nausea, dizziness, thirst, heavy sweating and elevated body temperature.

On the other hand, heat stroke is the most serious heat-related illness and can be deadly. It happens when your body can no longer control its temperature in entirety.

"The only avenue for heat dissipation in this condition is the production of sweat and the evaporation of that sweat to try to cool them, but there's going to be an increase in skin blood flow to the skin and that creates a burden on the heart, the cardiovascular system," Kenny explains.

According to the province of Manitoba's Health team, when heat stroke occurs, a person's core body temperature rises to over 40 degrees Celsius. The longer a person’s body temperature is above 40 degrees, the greater the likelihood of permanent disability or death.

Someone suffering from a heat stroke may experience confusion, slurred speech, loss of consciousness, profuse sweating and seizures.

Who is at risk of heat stroke and heat exhaustion?

Elderly people are particularly at risk for heat-related illnesses. They may not have access to air conditioning or turn it on because they don't believe the heat is a threat. Kenny stresses the importance of checking on elderly family members during hot summer days, especially those who live alone.

"As a person gets older, there's about a four to five per cent decline in your body's capacity to lose heat per decade," Kenny explains. "For the same level of heat stress [between a young and elderly person], an older person would not be able to thermal regulate adequately to prevent a greater rise in temperature."

If you can’t visit an elderly friend or family member in person, have a neighbour check on them, or call them on the phone. Kenny also suggests asking them some simple questions to make sure they’re doing alright.

"If a person is under stress, they're going to show irritability. They may even become more reclusive, they might not want to talk as much," he says. "Those are clear signs that a person is struggling."

Additionally, people with certain conditions like diabetes are at greater risk during heat waves because high temperatures affects blood glucose levels.

"If I have an older healthy person, and then I have a person with type two diabetes of the same age, same body mass, etc., the person with type two diabetes has about a 20 per cent lower capacity to dissipate heat," Kenny explains.

Lastly, young children, people who work outside and those who exercise in the heat are at higher risk of heat exhaustion and heat stroke.

How to help someone suffering from heat stroke

If you see someone suffering from heat stroke, you should call 911 immediately. The Canadian Red Cross also suggests removing the person from the heat, loosening or omitting tight clothing, fanning the skin, and immersing the person's body in cool water.

For heat exhaustion, it’s also advised to get the affected person out of the heat, loosen or remove tight clothing, pour water on the torso and fan the skin.

Staying safe in the heat

If it’s hot outside, there are several ways you can prevent heat-related illness. Wear light and loose-fitted clothing, reduce outdoor exercise, seek air conditioning, wear sunscreen and stay hydrated. Never leave people or pets inside a parked car, and remember that extreme weather can affect anyone.

"I've seen some of the most fit athletes suddenly just you know, they train in the heat […] just go out for a nice jog and collapsed and been hospitalized. I've seen workers that think they're resilient and it just takes that one day," Kenny says.

Additionally, if you’re travelling somewhere with extreme temperatures such as parts of Europe, be mindful that fatigue and jet lag makes you more susceptible to heat-related illness.

"Sleep is also a factor that can affect your well-being. That in itself can push you over the edge," Kenny says. "If you're under stress, any kind of emotional stress, mental stress, that in itself, can cause you to be less able to tolerate the heat."

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