Code Orange air quality alert in effect for several counties

The Pennsylvania Department of Environmental Protection has issued a Code Orange air quality alert for Thursday.

The alert will be in effect for Allegheny, Armstrong, Beaver, Butler, Washington, western Westmoreland and western Fayette counties.

According to the DEP, a Code Orange air quality alert means that air pollution concentrations within the region may become unhealthy for sensitive groups

The DEP said, “Sensitive groups include children, the elderly, and people suffering from asthma, heart disease, or other lung diseases. The effects of air pollution can be minimized by avoiding outdoor exercise or strenuous activity.”

So, why the bad air quality today?

You can blame warmer air. Not at ground level but a couple of thousand feet above the ground. It's called an inversion.

When the air aloft is warmer than the air at the surface air molecules get trapped close to the ground and don't rise into the atmosphere. The pollutants in the air also get trapped at ground level and can reduced air quality over time, especially as more and more pollutants get released into the air.

You also generally need very light wind or no wind at all. There is nothing stirring the atmosphere to mix the air. Usually, a slight change in pattern can help kick enough of a breeze up to “unclog” the works and get the air back to normal.

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