Canadian Wildfires Give Toronto the World's Worst Air Quality

On July 15, 2026, smoke from 838 active Canadian wildfires — mostly in northwestern Ontario — gave Toronto the world's worst air quality, per Reuters. Environment Canada issued a 'High' risk Air Quality Health Index alert, a warning level advising vulnerable groups to limit outdoor activity. The smoke also drifted across the Great Lakes into New England, degrading air quality there.