Canadian wildfire smoke blankets large parts of the U.S., triggering hazardous air quality

Smoke from major Canadian wildfires blankets the Midwest, Mid-Atlantic and Northeast, affecting about 109 million Americans with hazardous to very unhealthy air quality in cities like Chicago, Detroit, Philadelphia, Baltimore, Washington and New York. Officials urge staying indoors and using NIOSH-certified respirators for outdoor activity. Winds from Quebec are expected to push the plume east and then clear some areas this weekend, though a late storm could worsen conditions before Sunday events, while fires continue burning across Ontario and the Northwest Territories.