INDIANAPOLIS (AP): Indiana officials are warning of poor air quality in four regions of the state Saturday.

The Indiana Department of Environmental Management issued ozone advisories for Clark, Floyd, Harrison, Jackson, Jefferson, Scott, and Washington counties in southern Indiana; Daviess, Dubois, Gibson, Greene, Knox, Perry, Pike, Posey, Spencer, Vanderburgh, and Warrick counties in southwestern Indiana; Lake, Porter, LaPorte counties in northwestern Indiana; and for much of central Indiana including the cities of Anderson, Bloomington, Carmel, Indianapolis and Muncie.

IDEM says elderly residents, children and anyone with heart or lung conditions should reduce their physical exertion in the affected areas.

Ground-level ozone can cause coughing and breathing difficulties. It’s formed when sunlight and hot weather bake vehicle exhaust, factory emissions and gasoline vapors.

IDEM urges people to help reduce ozone by conserving energy.