05/18/2026
Air Quality Alert (AQA) Code Orange for Monday, May 18, 2026 - Ozone for the following counties in eastern and southcentral Pennsylvania:
📍Philadelphia, Bucks, Montgomery, Chester, Delaware, Lehigh, Berks, Northampton, Cumberland, Dauphin, Lebanon, Lancaster, and York.|
Ozone forms when airborne chemicals such as nitrogen oxides and volatile organic compounds (called “precursors”) mix with sunlight. These chemicals often come from cars and factories, and they build up most in the summer when the days are long and sunny. (Wildfire smoke can also add more of these chemicals.) Ozone pollution is usually worst in larger cities where there is lots of exhaust from cars and industrial air emissions.
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 Alert 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.
Check www.airnow.gov for current conditions in their area.
