The Chicago area recorded ozone levels of 156 late Monday afternoon. Levels above 100 are considered unhealthy. Residents with respiratory issues, children and the elderly are advised to stay indoors and limit exposure to air outside until Tuesday evening.

At 9:57 a.m. on Monday, the National Weather Service reported an air quality alert in effect until 10 p.m. for Oneida, Seneca, Cayuga, Onondaga, Tompkins, Madison and Cortland counties.