Updated 5:20AM CDT…
The Illinois Environmental Protection Agency has declared an Air Pollution Action Day will be in effect for the Greater Chicago Metropolitan Area in Illinois (gray-shaded area on the headlined map) until midnight CDT Saturday night.
A steady west to southwest flow of hot humid air will flow up the backside of a nearly stationary huge high pressure air mass centered off the Mid-Atlantic eastern seaboard coastline into Illinois and the Chicago area. While there may be isolated showers or thunderstorms, widespread ozone and or particulate levels are expected to be at or above the unhealthy for sensitive groups category of the air quality index.
Children and adults, especially those with pulmonary or respiratory disease such as asthma should limit prolonged outdoor activities.