Wildfire Smoke Chokes Toronto, Ranks City's Air Among World's Worst

Hundreds of Canadian wildfires send orange haze over Ontario and into northern U.S. cities.

Wildfire smoke engulfed Toronto this week, turning its skies orange and giving the city, at times, the worst air quality of any major city on Earth, surpassing Kinshasa in the Democratic Republic of Congo and New Delhi, India, according to a pollution monitor cited by Al Jazeera.

The smoke drifted across Ontario and into the northern United States, threatening air quality in American cities downwind, Al Jazeera reported.

The haze stems from a severe wildfire season in Canada, where 838 fires were actively burning nationwide, according to figures from the Canadian Interagency Forest Fire Centre cited by the BBC. The orange skies over Ontario echoed similar smoke events in recent years that have pushed hazardous air deep into the U.S. Midwest and Northeast.

Al Jazeera reported that the smoke's spread had prompted concern in American cities in the fire's path, though the immediate impact was most severe in Toronto itself, where residents faced the worst conditions.

Canadian officials have not indicated when the fires might be brought under control, and the scale of this year's blazes — with hundreds burning simultaneously — suggests the smoke risk to both Canadian and U.S. population centers could persist through the summer.

— Compiled from reporting by Al Jazeera and the BBC.