Weather Service says stagnant air affecting Clark County communities until Thursday

The regional forecast office of the National Weather Service said stagnant air conditions in the greater Vancouver area are expected until later this week.

An advisory stays in place until 2 p.m. Thursday for the cities of Battle Ground, Ridgefield, Yacolt and Amboy, according to the weather service.

“Most of Clark County excluding areas near the Columbia River Gorge” will be affected, meteorologists said.

A high pressure system lingering over an area for several days creates the conditions for stagnant air about two times every year, said Laurel McCoy, meteorologist with NWS in Portland. An inversion is trapping warm air around 2,000 to 3,000 feet while colder air, along with smoke and other harmful airborne substances, is stuck below, McCoy said.

Rain is expected by Friday, which should knock loose the stagnant air and improve conditions, McCoy said.

“The advisory could be extended by a couple hours, but it’s still up in the air,” she said.

The air mass stuck over the area is increasing pollution to dangerous levels, the weather service said.

“Persons with respiratory illness should follow their physicians’ advice for dealing with high levels of air pollution,” it said.

Southwest Clean Air Agency lists Vancouver’s current air quality as unhealthy.

People with asthma, respiratory infections, diabetes, lung or heart disease, or who have had a stroke, should stay indoors, the agency warns. It also encourages people to avoid exercising outdoors.