By Wa Lone and Kyaw Soe Oo
TORONTO, July 15 (Reuters) – Toronto’s air quality ranked the worst among major cities globally on Wednesday as wildfire smoke from northwestern Ontario blackened skies and prompted health warnings and calls for residents to limit outdoor activities as temperatures remained high.
Environment Canada reported an Air Quality Health Index (AQHI) reading of 10+, classified as “very high risk,” for Toronto, while forecasts suggested hazardous conditions could persist through Thursday night.
IQAir, a Swiss air quality technology company, ranked Toronto as having the worst air quality across the globe, surpassing Kinshasa and Delhi.
Wildfire smoke from northern Canada in recent years has also spread across wide swaths of the United States, spurring health warnings, particularly for infants and the elderly who are more susceptible to smoke particles.
A video shared on social media showing a Canadian National train on fire near Armstrong, Ontario, went viral. Canadian National said it had temporarily suspended rail operations near Armstrong as a precaution due to wildfire activity in the area. CN employees in the area and residents of Armstrong were evacuated on Monday night, CN said.
The Government of Canada has said that wildfire season began more slowly in 2026 than in 2023 or 2025 — the two worst seasons for wildfires — but warned that fires were likely due to warmer than usual temperatures across the country.
Some 835 active fires were burning in the country on Wednesday, and 112 according were considered out of control, according to the government. So far, 1.9 million hectares (4.7 million acres) have burned. Most of the fires were in the central provinces of Manitoba, Saskatchewan, and Ontario.
Greg Evans, professor at University of Toronto, Chemical Engineering & Applied Chemistry, said it was the first time the city had been simultaneously hit with severe heat and wildfire smoke to his recollection.
“I expect that this will occur more frequently over the coming decades so cities and residents need to prepare for this in the future,” he said.
Paula Oreskovich, a Toronto resident, said she noticed the haze and smell of smoke when she stepped outside in the morning. She said the poor air quality was concerning, particularly as wildfire smoke has become a recurring feature of recent summers.
“I think you have to be silly if you’re not going to be concerned about climate change. It’s definitely here, it’s definitely happening, and it’s happening globally,” Oreskovich said.
Toronto has also faced severe heat in recent days. Environment Canada maintained a heat warning for the city, forecasting a high of about 33 degrees Celsius (91 Fahrenheit), with humidity making temperatures feel closer to 39 C.
“Reduce or reschedule strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation,” Environment Canada posted in an advisory note.
IQAir recorded a U.S. Air Quality Index reading of 184 for the city, a level considered unhealthy.
(Additional reporting by Ed White in Winnipeg; Editing by Caroline Stauffer and Nick Zieminski)
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