Harrisburg, PA – The Pennsylvania Department of Environmental Protection (DEP) has declared a Code Orange Air Quality Action Day for ozone for Thursday June 12, 2025, in the Philadelphia area (Bucks, Chester, Delaware, Montgomery, and Philadelphia counties) and for southwest Pennsylvania counties (Allegheny, Westmoreland, Beaver, Butler, Armstrong, Washington, and Fayette).
Hazy sunshine through low level smoke from Canadian wildfires in tandem with high temperatures around 90 degrees and light southwest winds will act to produce significant ozone concentrations in the code ORANGE range Thursday afternoon. Sensitive individuals of the population should take precautions and limit outdoor activity during the afternoon. Residents are encouraged to check www.airnow.gov for current conditions in their area.
Ozone is formed when airborne chemicals such as nitrogen oxides and volatile organic compounds (called “precursors”) react with sunlight. High ozone levels are most common during summer months when there are long days with plentiful sunshine and high levels of ozone precursors combine. Although ozone precursors are most often generated by car exhaust and industrial air emissions, wildfire smoke can provide additional precursors. Ozone pollution is most common in densely populated areas with higher amounts of car exhaust and industrial air emissions.
On a Code Orange Air Quality Action Day, young children, the elderly, and those with respiratory problems, such as asthma, emphysema, and bronchitis, are especially vulnerable to the effects of air pollution and should limit outdoor activities.
Residents and businesses within the Air Quality Action Day area are strongly encouraged to voluntarily help reduce ozone air pollution by:
- Driving less by carpooling or using public transportation;
- Combining errands to reduce vehicle trips;
- Limiting engine idling;
- Refueling cars and trucks after dusk; and
- Conserving electricity by setting air conditioning to a higher temperature and turning off lights that are not in use.
The U.S. Environmental Protection Agency’s (EPA) Air Quality Index (AQI) provides standardized color codes for forecasting and reporting daily air quality. Green signifies good air quality; Yellow means moderate air quality; Orange represents unhealthy pollution levels for sensitive groups of people; and Red warns of unhealthy pollution levels for all. An Air Quality Action Day is declared when the AQI is forecasted to be Code Orange or higher.
For more information, visit DEP at www.ahs.dep.pa.gov/AQPartnersWeb, EPA’s AirNow at www.airnow.gov.
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