Heavy smoke from several large wildfires blazing in Canada and Minnesota is expected to engulf large swaths of the Midwest and Northeast U.S. this week. Winds are carrying the smoke southeast, exposing millions of people to dangerous air pollution.
More than 100 wildfires are burning in Canada. In Ontario, roughly 100 wildfires are raging out of control, sending smoke streaming more than 1,000 miles from their origin.
Around 100 million Americans could be affected by the wildfire smoke, though impacts will vary by location.