Smoke from wildfires in Canada affects millions in north-central and northeastern United States

Thousands of people were evacuated from a remote wilderness area in Minnesota as smoke from large, active wildfires in Canada and Minnesota blankets vast areas of the Midwest and the Northeast, triggering air quality alerts and health concerns.

According to the AP, more than 100 wildfires remain active in Canada, and winds are carrying the smoke southeast. Unhealthy air quality advisories extended Wednesday from Minnesota, through Toronto, to New York, during a week also marked by unusually high temperatures.

Authorities closed the Boundary Waters Canoe Area Wilderness in northeastern Minnesota on Tuesday, where some 17 fires sparked by lightning more than a week ago continue to spread. The area, covering approximately 1.1 million acres, is accessible primarily by canoe.

Spokespersons for the U.S. Forest Service estimated that between 6,000 and 10,000 people were inside the reserve at the time of the closure. Park rangers are working to evacuate visitors, a task that, according to authorities, may require hours of paddling or even transporting canoes overland.

The National Weather Service recommended staying indoors to avoid simultaneous exposure to smoke and extreme heat. It is also advised to wear N95 masks if it is necessary to go outside and to maintain indoor air quality by closing windows and using air purifiers or air conditioning systems.