Code Orange declared for Philly area due to poor air quality

The latest iteration of Canadian wildfire smoke has passed for the Philadelphia region, but air quality alerts are again in effect.

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

The Code Orange also extends to the Pittsburgh area, including Allegheny, Armstrong, Beaver, Butler, Fayette, Washington, and Westmoreland counties.

Ozone, a gas that’s harmful when breathed in, forms from a combination of heat and different pollutants.

An 8-hour average of ozone concentrations in the Code Orange range is expected Wednesday, state Department of Environmental Protection officials said, due to residual smoke, increasing weekday emissions, light winds, and temperatures over 90 degrees.

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.

Local conditions may fall above or below Code Orange range. Residents are encouraged to visit AirNow.gov to check local conditions.