Air quality alerts are in place on Thursday across at least 17 states, from Minnesota to New Hampshire to Virginia, as dangerous smoke drifts into the U.S. from Canadian wildfires.

Smoke from the more than 180 wildfires burning in Canada is traveling more than a thousand miles to reach places like New York City. At least another nine large fires are burning in northern Minnesota.

Detroit, Michigan, and Minneapolis, Minnesota, have the worst air quality in the world among major cities, with extremely hazardous air quality. 

Detroit reaching an air quality index, or AQI, around an astronomical 600 on Thursday morning. The most dangerous level, “hazardous,” begins at an AQI of 300 plus. 

This extreme smoke is expected to continue east and continue through the Northeast. 

New York City could see orange skies on Thursday, as plumes of hazardous smoke make their far enough to be dense. 

By Friday morning, the smoke is expected to push farther south, affecting areas through Ohio and Virginia, including D.C. and Baltimore, through the day on Friday.