Illinois Unknown Air Quality Alert | Effective 07/17/2026 12:22

The Illinois Environmental Protection Agency has determined that the "Air Pollution Action Day" designation will remain in effect for the greater Chicago Metropolitan Area through Saturday night July 18th. Additionally, the ongoing "Purple Forecast Air Pollution Action Day" designation also remains in effect until midnight tonight. A Chicago area "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 (AQI) for multiple days. Ozone is expected to be the primary pollutant of concern although smoke/PM2.5 may also become a concern later in the work week. Active children and adults, especially people with pulmonary or respiratory disease such as asthma, should limit prolonged outdoor activity. Area residents are urged to reduce pollution levels. Air quality forecasts, current air quality, and tips on how you can reduce your emissions can be found at www.airnow.gov Media Contact...Illinois EPA