Chicago area warned of air pollution on Friday

Chicago-area residents are being warned about high levels of air pollution.

The Illinois Environmental Protection Agency has declared an Air Pollution Action Day in the metro Chicago area for Friday because of elevated ground-level ozone.

Ozone is an unstable gas created when volatile chemicals and exhaust from smokestacks and tailpipes “cook” in the heat and sun.

The pollutant can be harmful to people with heart and lung problems and to those who exercise outdoors. Health officials recommend that everyone limit outdoor activities on Friday and try to stay in a cool place.

They also discourage activities that can contribute to ground-level ozone, including driving vehicles and mowing lawns.

Friday’s high temperature in Chicago is projected to be in the 90s.