Toronto records worst air quality as wildfires spread

Toronto experienced the worst air quality of any major city in the world on Wednesday, July 15, 2026, as dense smoke from wildfires in northwestern Ontario blanketed the region and drifted into the northeastern United States. The hazardous conditions prompted widespread health warnings and the cancellation of public events, with officials urging residents to limit outdoor activities.

Environment Canada reported an Air Quality Health Index reading of 10, or "very high risk," for Toronto. The Swiss air quality monitoring platform IQAir ranked the city first globally with an index of 192, placing it in the unhealthy category and ahead of typically polluted cities like Kinshasa and Delhi. Meteorologists attributed the severe smog to strong northwesterly winds carrying smoke from ongoing fires, exacerbated by a high-pressure system also responsible for a concurrent heat wave. Relief is not expected until winds shift on Friday, with some improvement forecast for the weekend.

Health officials warned of significant risks from prolonged exposure. The smoke contains fine particulate matter that can travel deep into the lungs and potentially enter the bloodstream, leading to respiratory...