The state Department of Environmental Protection has declared Tuesday a Code Orange Air Quality Action Day for fine particulate matter for several Mon Valley communities.
Officials said areas impacted include Clairton, Glassport, Liberty, Lincoln and Port Vue.
The U.S. Environmental Protection Agency’s Air Quality Index provides standardized color codes for forecasting and reporting daily air quality.
An Air Quality Action Day is declared when the AQI is forecast to be orange or higher.
Orange represents unhealthy pollution levels for sensitive groups of people, according to a DEP release.
Green means good air quality, yellow means moderate air quality and red warns of unhealthy pollution levels for everyone.
A strong temperature inversion Tuesday morning and light south to southwest wind in the afternoon will likely contribute to daily average concentrations of fine particulate matter in the Code Orange range, according to the DEP.
The highest hourly concentrations will most likely happen between 10 and 11 a.m.
“A strong temperature inversion is when the temperature increases with height, so it gets warmer as you go up,” said Michael Brown, meteorologist with National Weather Service in Pittsburgh. “The air’s not allowed to naturally mix as it otherwise would be. It takes a while for it to start mixing. That in itself isn’t harmful, but with the regular pollutants in the air, they can’t mix out as they otherwise would from wind and mixing. You’re taking that out of the equation in the morning.”
DEP officials said young children, the elderly, and those with respiratory problems, such as asthma, emphysema, and bronchitis should limit outdoor activities on an air quality action day.
