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It’s getting hot in here! – Protecting the most vulnerable from indoor heat

As the weather heats up around the country, we don’t often pause to think of the effects heat can have on our bodies. The elderly are particularly vulnerable to extreme heat in their homes, which can have a devastating impact on their health and, in extreme cases, even lead to death. Researchers are looking into why this happens, and how we can better protect those most at risk.

In Canada, because of our traditionally cold winters, homes are designed to retain the heat. This isn’t ideal when extreme heat comes around, especially for those who don’t have air conditioning.

“Many of the people who are impacted are the most at risk in our society, particularly older adults but also others, including those living with mental illness or who have limited means to take protective actions,” explains Paddy Enright, Policy Analyst at Health Canada. “These may also be people who are more socially isolated and who may not have people checking in on them, which makes them more likely to succumb to the heat inside their home.”

Science at the forefront

The frequency and severity of extreme heat events is increasing with climate change. And we must make sure our homes are well adapted to these changes.

Researchers are working on finding out how the heat affects people, and what specific factors make them more vulnerable. Dr. Glen Kenny, Director of the Human and Environmental Physiology Unit at the University of Ottawa, is working on determining the temperatures at which people could be more susceptible to heat illness and death inside their homes.

Over the last decade, Dr. Kenny’s lab has been developing unique ways to measure just how hot the human body gets, and how it naturally cools itself. “We have been able to determine that as people age, they have a lower ability to lose heat (primarily through increases in sweating) causing them to store more heat and experience greater increases in core temperature when exposed to hot environments,” explains Dr. Kenny.

Our body naturally cools itself by sweating. When the sweat evaporates from our skin, it takes with it some of the heat that was on our skin. When it’s too humid outside, sweat can simply drip off the skin without cooling the body, which causes core temperature to rise more quickly.

Dr. Kenny’s team has also determined that older adults, or those with chronic conditions, don’t perceive or respond to the effects of heat the same way as younger people. In fact, older adults felt less affected, which may indicate an inability to perceive the threat to their health when exposed to extreme heat. That puts them at greater risk, because they might not realize what is happening until it’s too late.

Prolonged exposure to indoor heat may cause older adults to feel generally unwell. Their blood pressure can drop, which puts added stress on the heart. Even while doing something simple, like getting up from a seated position, they are at greater risk of a fall-related injury.

Dr. Kenny’s team has worked to identify safe indoor temperature limits for vulnerable people during an extreme heat event. They found that a single-day exposure to temperatures of 26°C will likely not create issues for older adults. However, prolonged exposure to temperatures greater than 26°C but less than 31°C may pose a risk to health in some adults. Whenever possible, sustained exposure to temperatures 31°C or above should be avoided for people susceptible to heat.

Protecting ourselves from the heat

Just as we bundle up for winter, we need to prepare when the heat comes around. Our bodies need time to get used to the heat. What seems hot for someone living in a northern community might be just comfortable for someone from a hotter country. Temperature isn’t an absolute measure of the danger than can be posed by heat. Listen to your body, and pay particular attention to those most vulnerable to the effects of heat.

Air conditioning remains the most effective measure to stay cool, but not everyone has access at home. For those who don’t, municipalities often offer cooling rooms, or recommend going to an air conditioned location such as the mall or the local library.

“It’s important to ensure that people most at risk are able to go to these locations, including ensuring access for those with mobility issues,” says Enright. Don’t forget to check on people who may be isolated.

However, Dr. Kenny cautions that cooling centres aren’t always effective when dealing with a prolonged heat wave. “Cooling centres are effective at temporarily reducing someone’s core temperature, but it doesn’t remove all the heat from the body. When you go back into the heat, the body quickly experiences a rapid increase in core temperature to levels observed prior to entering a cooling centre.” While they may feel better, they are not completely out of danger.

Other strategies to keep you cool include putting a cool wet towel around the neck or groin area. Taking a lukewarm bath (since cold water may cause a cold-shock response that may be harmful to some individuals), or soaking your feet in cool water can also help.

In the long term, we need to make changes to the way our cities are built. In fact, city cores can be several degrees hotter than surrounding suburbs. Since buildings are made to last, the decisions we make right now can have ramifications up to a century from now.

With the knowledge gathered through research, there is no reason for people to die in Canada of extreme heat, especially inside their home. “Almost every heat death is a preventable death. We can take action and have a healthier future,” says Enright.

Additional resources

Extreme heat events: How to protect yourself

Human and Environmental Physiology Unit, University of Ottawa


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