Canadian wildfires in Manitoba and Saskatchewan have prompted air quality alerts in Minnesota, Wisconsin and Michigan on Wednesday and Thursday as residents are advised to "limit prolonged or heavy exertion.

Wildfire smoke from Canada is blanketing the skies in the Midwest, leaving millions with dangerous breathing conditions.

Wildfire smoke drifting across the Great Lakes has caused air quality to plunge to hazardous levels in several states, affecting millions of people in major cities.