Ontario Wildfires Send Hazardous Smoke into U.S. Midwest and Northeast

Out-of-control wildfires in northwestern Ontario sent hazardous smoke across the U.S. border on July 16, exposing millions of residents in Minnesota, Wisconsin, Michigan and Illinois to unhealthy air. Detroit, Toronto, Minneapolis and Chicago ranked as the four most polluted cities in the world on the IQAir tracker that morning.

Forecasters said the smoke plume would reach New York and the Northeast later in the day. New York state issued an air quality health advisory for fine particulate matter across the New York metro area and Long Island. The advisory warned that outdoor conditions would be unhealthy for everyone, with even worse readings expected in central and western parts of the state.

Authorities encouraged residents to limit time outdoors. Libraries and train stations distributed free masks, and hundreds of cooling centers opened for people without air conditioning. Mayor Zohran Mamdani stated that the combination of dangerous heat and unhealthy air posed a serious threat.

Detroit recorded air quality index readings near 700, according to the U.S. Environmental Protection Agency tracker. The Michigan Department of Environment, Great Lakes and Energy said hazardous conditions were expected to continue through Friday.

The agency noted that its smoke model only extends 48 hours and currently shows improvement on Saturday, though smoke could linger and recirculate. In Canada, more than 130 active fires were reported in northwestern Ontario, with at least 60 classified as out of control. Provincial authorities requested additional federal assistance, including air support for evacuations of remote communities.

More than 150 fire crews and nearly 50 firefighting aircraft were working around the clock, according to Premier Doug Ford. Canadian wildfires have burned 1.9 million hectares so far this year. That total remains well below the record 18 million hectares scorched in 2023.