The Air Quality Alert will remain in effect through Friday night and expires at midnight. Organizers at Lollapalooza said they have six medical tents inside the park to help if anyone needs medical assistance. Poor air quality continues in Chicago on Friday as events including Lollapalooza and Fiesta del Sol enter their second day.

Wildfire smoke drifting across the Great Lakes has caused air quality to plunge to hazardous levels in several states, affecting millions of people in major cities.