Air quality alerts can change quickly during wildfire smoke events. Here’s what Code Orange and Code Red mean, who is most at risk and when you should limit time outside.

As haze from Canadian wildfire smoke continues to move across Pennsylvania on Friday, state health agencies have declared a Code Purple Air Quality Alert for communities across the Commonwealth.

According to the Pennsylvania Department of Protection, a Code Purple alert means everyone should avoid prolonged or strenuous outdoor activities, and sensitive groups such as children, elderly reside...