Out-of-control wildfires in the Canadian province of Ontario are forcing mass evacuations and sending dangerous smoke billowing into the United States. Millions are exposed to unhealthy air as a result.
US states near the Canadian border, including Minnesota, Wisconsin, Michigan, and Illinois, are particularly affected. Forecasters predict air quality will continue to deteriorate in the Northeast, including New York City.
A tracker listed Detroit, Toronto, Minneapolis, and Chicago among the world's most polluted cities Thursday morning. New York state issued a health advisory, warning the air is "unhealthy" for everyone. Authorities encourage people to limit time outside.
In the Midwest, air quality index levels have surpassed hazardous thresholds. Detroit's reading hovered around 700. Michigan officials expect hazardous conditions to persist through Friday, noting smoke may linger and recirculate.
In Canada, more than 130 active fires are burning in northwestern Ontario, with at least 60 out of control. Provincial authorities have requested federal assistance, including air support for evacuating remote communities.
Canadian wildfires have scorched 1.9 million hectares so far this year. This remains far below the damage seen during Canada's worst wildfire season on record in 2023.