Toronto’s hazardous smoky haze has been displaced from the world’s worst air quality ranking, with Detroit now leading as the most polluted city.
Air quality monitoring data placed Toronto second on Thursday morning with a hazardous air quality index of 400, while Detroit recorded a more severe index of 518.
Smoke from northwestern Ontario wildfires continued drifting south into southwestern Ontario and the U.S. Midwest, covering the region in a dense, odorous orange haze.
The conditions raised health concerns, particularly for residents with asthma or other breathing difficulties.
On Wednesday, Toronto was the only North American city in the global top five, but by Thursday it was joined by Minneapolis at third with an index of 369 and Chicago at fourth with 213.
Toronto had briefly held the top global position on Wednesday with an index of 192 before conditions worsened elsewhere.
Other heavily affected cities included Kinshasa at fifth with 157, Delhi with 145, Jerusalem with 131, Lahore with 124, Tel Aviv with 123, and New York City at tenth with 109.
Montreal ranked 79th with a moderate index of 54, while Vancouver placed 106th at 40, classified as good air quality.
Despite slight visual improvement Thursday morning, many Toronto-area residents reported a stronger smell of charred wood and ash than the day before.
One Mississauga resident said the smoke seemed lower to the ground and that his partner, who has asthma, required a rescue inhaler after struggling on a bus the previous afternoon.
Another local resident described the air as resembling a large campfire, though the sky appeared less orange than on Wednesday.
Relief is expected by Friday as a weak weather system moves into the region, shifting winds away from the Greater Toronto Area and breaking the week-long heatwave.
Meteorologists cautioned that air quality warnings may be lifted but temperatures will remain warm through the weekend.
Until then, health experts advise at-risk individuals to avoid outdoor activity and monitor local air quality readings.
Recommended precautions include limiting time outdoors during poor air quality, wearing a properly fitted N95 mask for unavoidable exposure, and using high-efficiency home ventilation filters.
