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,

Canada is battling more than 700 active wildfires across the country, roughly two-thirds of which are burning out of control, according to the Canadian Interagency Forest Fire Center (CIFFC). Smoke billowing from the blazes has blanketed central Canada and the northern U.S., prompting widespread air quality alerts.