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

Millions of people across the Upper Midwest and the Northeast are under air quality alerts Monday, as smoke from wildfires in Canada drift over the region

She explained that air quality is largely influenced by wind patterns. With wildfires burning in central Canada, northwesterly winds are carrying smoke into the northeastern U.S., impacting air quality across several states. That's why we're seeing air quality health advisories—like the one issued today for fine particulate matter.