LARGO, Md. (AP) — Prince George’s County fire officials are warning residents to be aware of unhealthy air quality.

Fire officials say a code orange air quality alert has been issued for Sunday and Monday. The alert is issued when ozone is expected to reach unhealthy levels for sensitive groups. That means active children and adults and those with lung diseases such as asthma should limit prolonged outdoor exertion.

READ MORE: Man Shot, Critically Wounded In East Baltimore Saturday, Baltimore Police Say

Sunlight and heat combined with emissions from vehicles, power plants and other sources raise ozone levels, creating unhealthy conditions on hot summer days.

READ MORE: Fort McHenry Celebrates New Citizens, Defenders Day Saturday

Fire officials say with temperatures forecast in the 90s, residents also should be aware of the heat and take frequent breaks in the shade or air conditioning and drink plenty of water.

MORE NEWS: Man In Stable Condition After He Was Shot In Face While Driving Early Saturday

(Copyright 2012 by The Associated Press.  All Rights Reserved.)