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 Michigan and New York.

On Aug. 6, the Wisconsin Department of Natural Resources has not extended its Wisconsin air quality alert — a decision it hasn't made in over a week.

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.