An air quality warning is in effect as smoke from wildfires in Manitoba and Saskatchewan blankets much of Nunavut’s Kivalliq region on Tuesday.

Toronto had the fifth most polluted air of the world’s major cities early Tuesday morning, according to Swiss air technology company IQAir’s ranking,

Smoke from Canadian wildfires is causing air quality concerns for millions of Americans in the Midwest and Northeast. Air quality alerts were in effect Tuesday in several states, including Wisconsin,