Toronto is bracing for another summer of dangerous air quality as wildfires continue to rage across northern Ontario, the Prairies, and Western Canada, with doctors warning that the health effects of wildfire smoke are more serious and more widespread than many realize. 

The worst air quality 
Toronto recorded the worst air quality in the world in early June, according to global air tracker IQAir, as smoke from more than 183 active wildfires in Ontario drifted south into the city. It’s a dramatic increase from the 100 wildfires recorded in the province at this time last year, and experts say it’s a troubling sign of what lies ahead. 

“We’re already seeing much higher than our 10-year average,” said Dr. Samir Gupta, a respirologist and associate professor at the University of Toronto. “It does look like we are in for a tough season.” 

 

Canada’s second-worst fire 

According to federal data, the 2025 wildfire season has already burned 3.7 million hectares of land, an area six times larger than Prince Edward Island, making it Canada’s second-worst fire year on record, behind only 2023. 

The resulting smoke has triggered air quality alerts in five provinces and one territory, and it’s not staying contained within Canadian borders. Smoke from Canadian fires drifted over parts of the continental US in early June, from Kansas City to Minneapolis. 

High chances of health risks 

Though Toronto residents are far from the flames, Dr. Gupta says the health risks are very real. 

“We see increased emergency room visits for things like asthma, COPD flare-ups, and even heart attacks and strokes,” he explained. “These particles are so small they enter the bloodstream through the lungs and start affecting the heart and other organs.” 

Even short-term exposure to wildfire smoke can cause headaches, coughing, eye irritation, dizziness, and in severe cases, chest pain or difficulty breathing. Gupta added that vulnerable populations, including seniors, pregnant individuals, people with chronic illness, and children, are at the greatest risk. 
However, even healthy individuals should be cautious. 

“When I see an AQHI [Air Quality Health Index] over 7, I won’t go for a run outside. I’ll exercise indoors,” Gupta said. “When you’re running, you breathe in twice as much pollution. It really can take a toll.” 
On smoky days, experts advise staying indoors, using HEPA air purifiers, and if you must go outside, wearing a fitted N95 mask to filter out fine particulate matter. 
This summer’s conditions are expected to worsen, with The Weather Network forecasting a hotter and drier climate around the Ontario–Manitoba border, resulting in more wildfire outbreaks and smoke movement. 
 
“The effects aren’t always visible, but they’re happening,” Dr. Gupta said. “You may not feel it, but the smoke is doing the damage.” 
