A thick plume of smoke from Canadian wildfires swept across the Midwest and New England on Thursday, prompting air quality alerts in multiple U.S. cities. The haze reduced visibility and created hazardous breathing conditions for millions of residents.

Meteorologists warned that the smoke could linger through Friday, with shifting winds potentially pushing the plume further south and east. Air quality indexes reached 'very unhealthy' levels in some areas, including Chicago, Detroit, and New York City.

Officials advised vulnerable groups to limit outdoor activity and use air purifiers indoors. The smoke outbreak follows a record-breaking wildfire season in Canada, where over 10 million hectares have burned this year. Conditions are expected to improve over the weekend as a cold front moves through.

Schools in several districts canceled outdoor recess, and some outdoor events were postponed. The Environmental Protection Agency urged residents to monitor local air quality reports via AirNow.gov. This marks the third major smoke event affecting the region this summer.