This scene from Flagstaff Hill on Friday, Jan. 14, 2022, shows how a temperature inversion — with warm air trapping cold air near the ground — can result in a layer of clouds over Baker Valley.

Baker County will be in an air quality advisory at least through Monday morning, Jan. 17, due to widespread temperature inversions that trap cooler air, along with smoke and other air pollutants, near the ground.

The Oregon Department of Environmental Quality (DEQ) issued the advisory for Baker and several other counties in Eastern and Southern Oregon: Douglas, Harney, Jackson, Josephine, Klamath, Lake and Malheur.

DEQ recommends residents in the affected counties take precautions including:

• Avoid strenuous outdoor activity and recreation.

• People with heart or lung problems, and young children, are especially vulnerable, and should stay indoors if smoke concentrations are high.

• Use high-efficiency particular air (HEPA) filters for indoor ventilation, or portable air purifiers.

• Avoid using wood stoves if possible.

Air stagnation tends to be a problem during temperature inversions, a situation when warmer air higher in the atmosphere traps colder air, which is more dense, in valleys.

Inversions can persist for many days, during which smoke and other pollutants accumulate.

Typically, air temperature drops as elevation increases, which is why it’s usually colder in the mountains than in adjacent valleys.

But that situation is reversed during an inversion.

As an illustration of the phenomenon, at 8 a.m. on Friday, Jan. 14, the temperature at the top of the chairlift at Anthony Lakes Mountain Resort, elevation nearly 8,000 feet, was 32 degrees. At the same time it was 23 degrees at the Baker City Airport, elevation 3,376 feet, 7 degrees along Highway 7 at the Sumpter Junction, elevation 4,245 feet, and 12 degrees at North Powder, elevation 3,255 feet.

The hourly air quality index at sites around Oregon is available online at

The lone air quality measuring station in Baker County, atop the David J. Wheeler Federal Building in Baker City, had been offline from Jan. 6 through Friday morning, Jan. 14.

But Lauren Wirtis, a public affairs specialist with the DEQ, said DEQ employees were able to get the station operating again. As of 11 a.m. on Jan. 14, the air quality index in Baker City was 18, which is in the good (0-50) category.

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