Code Orange air quality alert issued for multiple Philadelphia-area counties

PHILADELPHIA (CBS) -- A Code Orange air quality alert has been issued for multiple parts of Pennsylvania Monday, including several counties in the Philadelphia area.

According to the Pennsylvania Department of Environmental Protection (DEP), Philadelphia, Bucks, Montgomery, Delaware and Chester counties are all included in the Air Quality Action Day due to ozone pollution. According to meteorologist Kate Bilo, this happens frequently with a prolonged heat wave as pollutants become trapped near the Earth's surface.

In the Lehigh Valley, Berks, Lehigh and Northampton counties are also under the Code Orange alert.

Air quality in the "orange" category is considered unhealthy for sensitive groups of people, including children, the elderly and those with lung conditions like asthma, according to the Environmental Protection Agency's Air Quality Index. People included in those sensitive groups are urged to limit the amount of time they spend outside while air quality is poor.

According to the DEP, mostly sunny skies combined with high temperatures in the 90s and very light winds could create conditions for "robust ozone development" Monday afternoon.

A heat advisory is in effect for the Greater Philadelphia area until Tuesday evening, and feels-like temperatures on Monday will climb to between 100-102 degrees. On Tuesday, it'll feel like closer to 104-105 degrees.