2023 was the hottest year on record, and 2024 is keeping pace. Canada is at particular risk — warming at more than twice the global rate. Here’s what that means for our health, and the health system we rely on for care.
What is extreme heat?
Environment and Climate Change Canada (ECCC) has different criteria depending on typical weather conditions for a given region.
- Up north in the Yukon, a heat warning is issued for two or more consecutive days where the daytime maximum will reach 28°C or higher and nighttime temperatures will fall to a low of 13°C.
- In the southern interior region of British Columbia, on the other hand, a heat warning is only issued when daytime highs will reach 35°C or higher and go no lower than 18°C.
How do heat waves impact health?
Heat waves and prolonged exposure to heat can impact health in several ways:
- A major increase in body temperature can lead to conditions such as heat exhaustion and heat stroke. In extreme circumstances, this can result in death.
- Increased sweating can lead to dehydration, which can cause cramps, rash, weakness or fainting. It can also worsen existing kidney problems and other medical conditions.
- Blood flow is redirected to the skin as a way for the body to cool down, forcing the heart to work harder than usual. The additional strain can cause problems for patients with existing heart conditions.
Extreme heat also has indirect impacts on health. These include:
- Poor air quality. Higher temperatures and stagnant air can increase ozone and particulate pollution, particularly in big cities and dense urban centers. This is particularly harmful when combined with wildfire smoke, which much of the country saw in 2023.
- Increased workplace injuries. During the 2021 heat dome in British Columbia, compensation spiked by 180% ¾ with a third of claims from indoor workers.
- Research suggests rising temperatures may also increase mental health distress and gender-based violence.
Who is most vulnerable to heat?
Older adults and children are typically more sensitive to heat. So are people with pre-existing health conditions. Certain medications, such as some antidepressants, can make patients more prone to heat-related illnesses. And people without adequate housing, air-conditioning, or a sufficient and reliable supply of drinking water can also find dealing with the heat more challenging.
- Peak temperatures during B.C.’s 2021 heat dome reached over 40°C in many parts of the province. A report by the BC Coroners Service identified 619 deaths related to heat– 98% of them occurred indoors, and most of the deceased were over 70 (67%), had multiple chronic diseases and lived alone (56%).
- A June 2024 study by Statistics Canada reviewed the impact of extreme heat on mortality in 12 Canadian cities from 2000 to 2020. As in B.C., they found an increase in deaths during periods of extreme heat, particularly for adults over 65 and in cities with larger proportions of renter households.
What does this mean for our health system?
Illness from extreme heat waves places extra demands on a system already strained by a lack of primary care access and record ER wait times. Additionally, many of Canada’s health facilities — among the oldest public infrastructure in use, with about half built more than 50 years ago — weren’t designed to withstand extreme climate events.
Video Transcript
Climate change is a growing health threat.
Canada isn’t ready.
2023 was the worst wildfire season in Canada’s history.
Every province and territory was affected.
It’s just one of the many climate shocks already affecting health and health workers.
And Canada is warming twice as fast as the rest of the planet.
Current health threats may intensify.
Extreme heat can damage the brain, the central nervous system and other organs.
Climate-related anxiety and depression are increasing.
New threats may emerge.
The health workforce is already in crisis across the country.
About half of Canada’s health care facilities are more than 50 years old, – ill-equipped to operate through climate emergencies.
Our health system is part of the problem, accounting for more greenhouse gas emissions than aviation and shipping.
In fact, Canada is one of the worst health care polluters per capita. The system’s carbon footprint is equivalent to 500 coal-fired power plants.
We can do better.
The Canadian Medical Association is calling on the federal government to establish a Climate and Health Secretariat.
It would facilitate a pan-Canadian approach to the health impacts of climate change
and work towards a climate-resilient and low-carbon health system.
One large-scale inspiration is England’s National Health Service.
It has cut emissions equivalent to powering more than one million homes.
A hospital in Birmingham performed the first net-zero surgery in 2022.
Canada must also adapt its health care system to the new reality we live in
and mitigate climate change for a healthier future.
Our health system can be good for the planet and for patients.
Sign up for more information at cma.ca/climate
A report by the Canadian Climate Institute shows the impact of the BC heat dome on health infrastructure:
- Older buildings get hot. An acute care floor at Lions Gate Hospital reached 38°C. “In a few cases,” the report says, “fire departments flooded health clinic roofs with water to try to bring inside air temperatures down.”
- Chillers for some CT equipment failed. This would have “severely limited the ability to diagnose and treat strokes, traumas, and emergencies like acute appendicitis.”
- Air ambulances couldn’t land at a number of hospitals “because the hot air was too thin for them to safely hover and land.”
Responding to a changing climate
Summers today are just not what they used to be. We’re seeing an increase in the frequency, extent and duration of extreme climate events like heat waves across the country—even in typically moderate climates like Vancouver and Halifax.
The federal government has started doing rapid attribution studies on extreme weather events to help inform future planning decisions. In June 2024, ECCC declared for the first time that the above-normal temperatures seen in Ontario, Quebec, and Atlantic Canada that month were made two to 10 times more likely because of human-caused climate change.
The health system itself is part of the problem, accounting for 4.6% of Canada’s total greenhouse gas emissions — making us one of the worst health care polluters per capita.
The CMA has been calling for national coordination on more sustainable, climate-resilient health care. This includes advocating for the establishment of a climate and health secretariat in the federal government. Working with provincial, territorial and Indigenous governments and partners, the secretariat would develop a pan-Canadian approach to address the health impacts of climate change and create climate-resilient and low-carbon sustainable health systems.