The air quality warnings in place here last week were the result of forest fires raging in Quebec that were, in turn, the result of conditions that were ripe for such blazes, says a University of Waterloo professor.
“Broadly speaking last week, and a little bit before that, as well, we’ve had a stretch of abnormally hot and dry weather across a lot of Canada, so that meant that a lot of the what’s called fuel for wildfires – the wood – is ready to burn,” said Rebecca Saari, a professor in the department of civil and environmental engineering.
Saari said the risk for wildfire was higher than normal for this period across a lot of the country. “And that meant we had conditions ripe for wildfires, and wildfires sparked and they sparked across the country over the past few weeks.”
While there may have been some influence of smoke from fires burning in Northern Ontario, what we experienced in southwestern Ontario last week came mainly from wildfires burning in Quebec, she noted.
Warnings were issued in the region, where the Air Quality Health Index showed high risk levels reaching 8 on a scale of 10.
Then, the rain that started last weekend helped dissipate the smoke, and move the particulate matter from the air to the ground, she said. Although the air quality health index is showing better quality air, Saari suggests people remain vigilant, adding climate change means more such incidents are likely.
“Studies currently project increases in conditions for unmanageable fires, including in locations currently burning. If we do not act [to reduce climate change], this could mean increasing air quality impacts of wildfires in the future,” she said.
Wildfire smoke harms human health by increasing the amount of fine particulate matter in the air. These are particles that are 2.5 micrometres or smaller, said Saari. These particles can be small enough to travel deep into human lungs.
Jade Coyne is an adult respirologist who works at Grand River Hospital and St. Mary’s General Hospital and runs her own out-patient practice. She says people have individualized health risks to fine particulate matter.
“Any sort of exertion is a stress to the human body and, obviously, baseline factors: have they been training, do they have underlying exercise-induced asthma, are they quite good at baseline?
[These factors] impact how that workout is going to go, but if you layer in poor air quality, it’s just a little bit more challenging. So the system has to work harder and some of these particulate matters can end up deep into the lungs and they can be small enough to get trapped into our lungs and effectively they can, in some people, cause a little bit more respiratory symptoms,” she explained.
“Not everyone will be impacted by [poorer air quality], but people that maybe have asthma are a bit more sensitive or have underlying respiratory conditions might have a bit more coughing, tightness, wheezing, they also may have other symptoms like dizziness, scratchy throat, that sort of thing. So it’s just the fact that it could make your exercise more challenging. It can make your day to day activities of daily living more challenging if the air quality is poor and you’re out completing a strenuous task or even just a regular task.”
Coyne recommends people pay attention to the air quality health index for their region and assess their own level of risk and stay inside if needed, or delay intense activity outdoors.
“It’s really dependent on the underlying individual, but I think that when we get to that moderate risk, moderate to high risk, we need to be more cognizant. And even for the average individual, that might not be the day to go outside for training for your half-marathon,” she said.
As well, Coyne recommends checking in on people who need to stay inside due to poor air quality, because this can be isolating.
Saari points out staying indoors is often the recommendation for vulnerable people, but in future she says society will need to start thinking about equitable access to clean, indoor air for future extreme events.
“A lot of the adaptation advice is for folks to limit their time outdoors by moving somewhere inside that’s clean. And not everyone has equal access to a clean indoor environment. This is something, in the short term, we can continue to advise people that way, but in the long term, we’ve got to think about access, equal affordable access to clean, indoor air,” she said.
At press time, the Canadian Interagency Forest Fire Centre was reporting 149 active fires in Quebec, and the Ontario Ministry of Natural Resources and Forestry reported 34 active wildfires across the northeast region, and 23 active fires in the northwest region.
So far this year in Ontario there have been 180 wildfires. In 2022 there were 79 fires total. The ten-year average for wildfires in the province is 157 annually.