Several counties in Southwestern Pennsylvania are among 20 that have been put under a code orange air quality action day for fine particular matter, the state Department of Environmental Protection announced Monday.
Among the affected counties are Allegheny, Armstrong, Beaver, Butler, Fayette, Washington and Westmoreland.
A code orange means pollution levels are unhealthy for sensitive people. 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.
The warmer weather is partly to blame.
“Fine particulate levels rose faster than expected over the past weekend due to much warmer air coming in aloft and at the surface along with much lighter surface winds,” the department said in the announcement.
A strong inversion — when colder air is trapped below a warm air mass — with calm winds and increased weekday emissions will bring air quality into the code orange range, the department said.
The pattern is expected to hold until Tuesday, when a cold front is forecast to pass through.
“The increasing mixing resulting from the frontal passage will bring air quality down to the moderate range on average during the day Tuesday,” the department said.
Brian Rittmeyer is a Tribune-Review staff writer. You can contact Brian at 724-226-4701, brittmeyer@tribweb.com or via Twitter @BCRittmeyer.
