An air-quality alert has been issued for Philadelphia and its surrounding Pennsylvania counties due to concerns about high concentrations of pollutants in the air,

The alert coincided with a forecast calling for temperatures approaching 90 and high humidity. In addition, locally heavy rains, due to thunderstorms, were falling around the area.

The National Weather Service issued several warnings as the afternoon wore on.

The code orange air quality, issued by the Delaware Valley Regional Planning Commission, is directed at sensitive groups, including children; people suffering from asthma, heart disease or lung diseases; and the elderly. The effects of air pollution can be minimized by avoiding strenuous activity or exercise outdoors, the National Weather Service says.