Air quality alerts are in place for portions of 10 states from Minnesota to Delaware as officials warn the smoke may become dangerous for sensitive groups.There are two U.S. cities in the top 10 globally for worst air pollution among major cities worldwide Wednesday morning: Chicago and Detroit.

The warning, effective until 7:15 p.m. MDT, covers Ada, western Elmore, Canyon and northwestern Owyhee counties.

Millions of people across the Upper Midwest and the Northeast are under air quality alerts Monday, as smoke from wildfires in Canada drift over the region