The Illinois Environmental Protection Agency has issued an air pollution action day alert for Evanston and the rest of the Chicago metro area effective until midnight tonight.
An 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 category of the air quality index.
Active children and adults especially people with pulmonary or respiratory disease such as asthma should limit prolonged outdoor activity.
Meanwhile the National Weather Service says we could get severe thunderstorms late tonight or early Thursday morning, but weather conditions are expected to stay hot and muggy at least through Friday.