According to the National Weather Service, the air quality alert remains in effect through midnight in parts of the Chicago area, including Kane, DuPage, Kendall, Grundy, Cook and Will counties.

Concern for poor air quality in the greater Chicago area remains as the Illinois EPA extends its alert until Thursday night. The city also is expected to get slightly warmer each day until the weekend.

An Illinois Air Pollution Action Day is declared when weather conditions are such that widespread ozone and or particulate levels are expected to be at or above the Unhealthy for Sensitive Groups (USG) category of the Air Quality Index for all or almost all of Illinois.