Though wildfire smoke was to blame for poor air quality earlier in the week, Wednesday and Thursday's alerts are due to high levels of ozone.

While an air quality alert continues for parts of the Midwest due to smoke from Canadian wildfires, northeastern Illinois was expected to shift away from air quality issues that persisted over the last week,

Wildfire smoke from Canada is a problem again in the Chicago area, with an air quality alert in place now extended through Wednesday night.