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4w ago

Canadian Wildfire Smoke Chokes Major Cities as Air Quality Alerts Persist

Over 200 active wildfires in western provinces are sending fine particulate into urban skies, prompting officials to advise vulnerable groups to remain indoors

Wildfire smoke (brownish colors) blankets much of the Central and Eastern U.S. on May 31, 2025. (Image credit: NOAA/CIRA/Colorado State University)
People watch as fire burns along Hatwai Road Saturday, May 31, 2025, in north Lewiston, Idaho. (August Frank/Lewiston Tribune via AP)
Cyclists commute in Toronto’s east end as wildfire smoke rolls into the city on June 6, 2025. (Sammy Kogan/The Globe and Mail)
A stock image shows a man coughing.

Overview

  • More than 200 wildfires burning across Alberta, Saskatchewan and Manitoba have driven smoke plumes into cities from Chicago to Ottawa as of June 6, 2025.
  • Chicago’s Air Quality Index was unhealthy for sensitive groups Friday morning with an alert in effect until midnight, and Toronto ranked third-worst in the world for AQI, according to IQAir data.
  • Pulmonary specialists warn that PM2.5 exposure can inflame the lungs and trigger acute spikes in heart attacks and strokes, particularly among people with asthma, COPD or coronary artery disease.
  • Health agencies recommend that older adults, children and those with chronic respiratory or cardiovascular conditions stay indoors with windows closed, use air filtration or wear N95 masks if venturing outside.
  • The Canadian Interagency Forest Fire Centre reports over 27,000 evacuations and nearly 200 structures lost, and forecasts indicate the fires and related smoke impacts may persist through the summer.