The air quality in the Tri-Cities was considered unhealthy for sensitive groups on Monday.
The Mid-Columbia and most of Eastern Washington is under an air stagnation advisory issued by the National Weather Service.
It was set to expire Tuesday morning but Monday was extended until at least 4 p.m. Wednesday
Limited air movement is keeping pollution trapped near the ground.
The air quality first deteriorated from a rating of “moderate” to “unhealthy for sensitive groups” in the Tri-Cities late Sunday afternoon, according to information posted by the Benton Clean Air Agency.
Sensitive groups should limit time spent outdoors. They include children, senior citizens, pregnant women, people who smoke, stroke survivors, people with colds and people with chronic health conditions such as asthma, diabetes and other heart and lung diseases.
Healthy people may begin to have symptoms such as watery or dry eyes, headaches and throat and sinus irritation.
Air quality also was unhealthy for sensitive groups or unhealthy for all people at times during the day in Sunnyside, Yakima and some areas near Seattle, Tacoma and Vancouver, Wash.
The Washington state Department of Ecology asks people to put off outdoor burning and to limit home heating with wood as much as possible during the air stagnation advisory.