The summer doldrums are marked by hot days, sunny skies, light winds. These conditions can lead to higher concentrations of particulate and ozone pollution at the surface. The EPA has issued an Air Quality Alert for Friday for southwestern Indiana.
Air quality is expected to become unhealthy for sensitive groups on Friday. Those with asthma and lung issues should avoid going outdoors or exerting during those times.
In normal conditions, pollutants are carried aloft and dispersed by winds. This dilutes the emissions and keeps them below harmful levels.
On Friday, warm air aloft will create an inversion or "cap" that will trap concentrated pollutants at the surface:
You should try to limit your polluting activities on Friday, and anytime it is feasible.