Some of the worst air quality will be right along Lake Michigan, as the majority of the Chicago metro area will be under that alert. The farthest counties like DeKalb, LaSalle, and Kankakee counties were in the clear as of Sunday. Forecast temperatures are expected to reach around 80 degrees for much of the Chicago area on Sunday.

"The air quality is officially dangerous in Chicago," says Brian Urbaszewski, director of environmental health programs at the Respiratory Health Association. "It's going to send people to the emergency room.