An air quality action day has been issued for five communities in the Monongahela Valley because of an increase in particulate matter pollution, according to the state’s Department of Environmental Protection.

The DEP issued a Code Orange Air Quality Day on Saturday for Clairton, and Glassport, Liberty, Lincoln and Port Vue boroughs.

It’s because of a strong temperature inversion Saturday morning, which DEP officials believe will contribute to daily average concentrations of fine particulate matter in the Code Orange range.

Inversions occur when air on the ground is warm, but cold air masses move above the warm air mass and trap pollutants near the surface. The DEP said that while concentrations will decrease this afternoon, levels will still remain in the Code Orange range.

Young children, the elderly and people with respiratory problems are especially vulnerable during Code Orange Air Quality Action days and should limit outdoor activities, the DEP said.

The agency encourages people to reduce fine particulate matter air pollution by reducing or not using their fireplace or wood stove; and to not burn leaves or trash.

People can visit www.airnow.gov for current conditions.

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