CHICAGO (CBS) — Thursday’s air quality is expected to take a turn for the worse.

An air quality warning will be in effect for Chicagoland’s counties, making it especially hard on those with respiratory problems.

CBS 2’s Mary Kay Kleist says ozone levels may climb to unhealthy levels.

Officials advise to keep an eye on the very elderly and young people.

Those with asthma or other pulmonary issues are advised to stay indoors.