5 things you need to know: How to protect your health from wildfire smoke
By Jessica Werb
Why indoor air quality and listening to your body is more important than you might think
If you took your lungs out of your chest and flattened them out, they would be about the size of half a tennis court. That’s according to Dr. Sarah Henderson, a professor at the UBC School of Population and Public Health and the scientific director of Environmental Health at the BC Centre for Disease Control. “When it’s smoky outside, your whole half a tennis court is being exposed to wildfire smoke,” she says.
There’s a lot you can do to protect your health when it’s smoky outside, Dr. Henderson explains in the video above. Paying attention to indoor air quality is key, as well as understanding who is most at risk.
Extreme heat is another summer hazard that can occur at the same time as wildfire smoke and puts more stress on your body. Dr. Henderson is the senior author on a new study that looked at how such double exposures impact your health, especially as they become more common with climate change. Below, she discusses her latest findings, and explains how to manage the combined effects of heat and smoke.
What did your study find?
Our research looked at the combined effects of heat and air pollution, including wildfire smoke, which is a growing concern that’s expected to become increasingly common due to climate change.
We examined more than 21,000 deaths outside of healthcare settings in the Greater Vancouver area during 13 wildfire seasons between 2010 and 2022. We found that the risk of death spikes when people are exposed to both elevated levels of fine particulate matter (PM2.5) from wildfire smoke and temperatures above 26°C.
But it’s not as simple as more smoke plus more heat means worse outcomes. Mortality risk during extreme heat rises exponentially, while mortality from wildfire smoke rises quickly at moderate exposures and then levels off. So, in terms of the risks to your health, extreme heat matters more. On average, being too hot with no smoke exposure is riskier than being exposed to smoke at cooler temperatures.
What happens to your body you’re exposed to both extreme heat and wildfire smoke?
When it’s very hot, your body is fighting hard to maintain its core temperature and keep cool, and when it’s smoky, your body is fighting hard to reduce the inflammation caused by smoke exposure. When these things happen at the same time, it puts more stress on your body. Our research confirms that together, the impact is greater than the sum of their individual effects, which can make it a risky combination.
Who is most susceptible during these heat and smoke events?
In all our analyses of the 2021 heat dome in BC—when it was not only very hot, but air quality was also quite poor due to wildfires and ground-level ozone—the population with the highest increased risk was people with schizophrenia. This is because people with schizophrenia can have a hard time recognizing when they are unwell, the illness can have cardiovascular impacts, and anti-psychotic medications can impede thermoregulation, among other factors.
Other populations at increased risk included people receiving income assistance—an indication of living in poverty–as well as older adults with underlying health conditions like heart failure, chronic obstructive pulmonary disease (COPD), kidney disease and substance use disorder. Although not included in our mortality studies, children and people who are pregnant are also at higher risk from extreme heat and wildfire smoke. For example, there is a higher risk of preterm birth on hot days and on smoky days.
What should people do to manage the effects of heat and wildfire smoke?
Respect the exposures and take precautions to reduce your exposure. I often say that you need to listen to your body—if your body’s telling you you’re not coping, don’t ignore that. Move to a good indoor environment with cleaner, cooler air, if you can. And remember that both exposures can have longer-lasting effects, including impacts on cardiovascular and brain health, so you’re helping protect your future self by taking these steps.
What’s needed to protect everyone during extreme heat and smoke events?
As a society we need to think about what policies and measures will ensure everyone has access to healthful and safe indoor environments during these extreme exposure events.
For instance, we have minimum indoor temperature standards, but no limits on the upper end. Ideally, there should be at least one room in everyone’s home that can be maintained at a maximum temperature of 26 degrees Celsius, regardless of what’s going on outside.
Similarly, we do not have an indoor standard for PM2.5, which is the primary pollutant we’re concerned about with wildfire smoke outdoors. Setting some national guardrails would help to protect the health of current and future generations in the changing climate.
Jessica Werb is a writer with UBC Faculty of Medicine. This article was published on June 20, 2025, and adapted from the original article by the Faculty of Medicine. To republish this article, please contact UBC Faculty of Medicine.
