Smoke from ongoing wildfires across Canada continued to drift into parts of the United States on Wednesday, causing hazy skies and triggering air quality alerts in multiple states across the upper Midwest and Northeast.

Smoke from Canadian wildfires is causing air quality concerns for millions of Americans in the Midwest and Northeast.

As Canada grapples with one of its worst wildfire seasons on record, smoke from the blazes have prompted air quality alerts across the U.S.