Code Orange declared for Philly, suburbs due to poor air quality

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Pennsylvania officials on Wednesday declared a Code Orange Air Quality Action Day for Ozone for the Philly region on Thursday. That includes Philadelphia, Bucks, Chester and Delaware counties.

The state Department of Environmental Protection cited mostly sunny skies, high temperatures in the mid- to upper-90s and light southwest winds as likely contributors to 8-hour average concentrations of ground-level ozone in the Code Orange range.

Ozone is formed from burning fossil fuels. Cars, trucks, power plants and industrial facilities contribute nitrogen oxides and volatile organic compounds which, when combined with sunlight, create smog, also known as ground-level ozone.

Under a Code Orange, air pollution concentrations may be unhealthy for vulnerable groups such as children, people with asthma, people with heart or lung disease and older adults.

Residents and businesses are also encouraged to reduce ozone air pollution by driving less, limiting engine idling and conserving electricity by setting air conditioning to a higher temperature and turning off lights not in use.

Residents are encouraged to visit AirNow.gov to check local conditions.

If you need a primer, here’s how to understand your air quality index.