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.

Health officials from Minnesota to Maine have issued alerts warning of poor air quality from wildfires burning in Canada. People are advised to limit outdoor exposure.

Hundreds of wildfires still burning in Canada are expected to undermine air quality across the Upper Midwest and Northeast into Tuesday.