Three days of Ontario wildfire smoke brought unhealthy air to 106 million person-days

Smoke from Canada's July wildfires exposed people across Canada and the United States to unhealthy, very unhealthy or hazardous air for nearly 106 million person-days between July 15–17. Over the peak impact period of July 13–18, moderate or worse air quality accounted for more than 769 million person-days. For a period, Toronto recorded the poorest air quality of any major city in the world.