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,

Wildfire smoke from the Bear Gulch Fire and Canadian wildfires continues to blanket Seattle, lowering air quality and prompting health warnings. Officials advise mask use and limited outdoor exposure.

Smoke from hundreds of wildfires in Canada is lingering over the northern U.S., spreading across to roughly a dozen states from Wisconsin to Maine.