For the second day in a row the Pennsylvania Department of Environmental Protection (DEP) has issued a Code Orange Air Quality Action Day for fine particulate matter for Monday, December 21, 2020, in southeastern counties of Pennsylvania including Bucks, Chester, Delaware, Montgomery, and Philadelphia, the southcentral counties of Cumberland, Dauphin, Lancaster, Lebanon, and York, the Lehigh Valley, and Berks.
A strong temperature inversion supported by snow cover, along with light winds associated with high pressure, are likely to contribute to daily average concentrations of fine particulate matter in the Code Orange range.
The U.S. Environmental Protection Agency’s (EPA) Air Quality Index (AQI) provides standardized color codes for forecasting and reporting daily air quality.
Green signifies good air quality; Yellow means moderate air quality; Orange represents unhealthy pollution levels for sensitive groups of people; and Red warns of unhealthy pollution levels for all.
An Air Quality Action Day is issued when the AQI is forecasted to be Code Orange or higher. On an Air Quality Action Day, young children, the elderly, and those with respiratory problems, such as asthma, emphysema, and bronchitis, are especially vulnerable to the effects of air pollution and should limit outdoor activities.
Residents and businesses within the Air Quality Action Day areas are strongly encouraged to voluntarily help reduce air pollution by reducing or eliminating fireplace and wood stove use, avoiding the open burning of leaves, trash and other materials, and avoiding the use of gas-powered lawn and garden equipment.