Children, older adults and those with respiratory conditions should avoid heavy outdoor activity Tuesday, July 14, due to ozone buildups harming the air quality, according to the Pennsylvania Department of Environmental Protection.

The department’s air quality index is set to orange Tuesday signifying the air is unhealthy for sensitive groups. It said sunny skies, light winds and temperatures in the low-to-mid 90s contribute to ozone buildup, which forms when airborne chemicals such as nitrogen oxides and organic compounds react with sunlight.

The code orange air quality alert is in effect for Butler, Allegheny, Armstrong, Beaver, Fayette, Westmoreland and Washington counties.

The department encourages residents and businesses to reduce air pollution by driving less or using public transportation, limiting engine idling, refueling after dark and conserving electricity.

Residents can check air quality at airnow.gov.