SPOKANE, Wash. — Unhealthy air quality is expected to plague areas of North Idaho on Monday as an Air Stagnation Advisory remains in effect until Tuesday morning. 

The National Weather Service issued the advisory on Friday for Spokane and surrounding areas as they expect a decline in air quality. The advisory, which is in effect until 9 a.m. on Tuesday, affects parts of central, east central, north central, northeast and southeast Washington, along with North and north central Idaho.

Some areas of North Idaho have experienced poor air quality since Wednesday, and many areas are still in the moderate or unhealthy for sensitive groups ranges on Monday morning.

Leaders with the Idaho Department of Environmental Quality say cities like Coeur d'Alene, Sandpoint and St. Maries could reach the unhealthy range on Monday. 

Spokane is sitting at moderate on Monday morning but the Spokane Regional Clean Air Agency says air quality could worsen to the unhealthy for sensitive groups range throughout the day. 

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Shawn Sweetapple, an air quality manager with the Idaho Department of Environmental Quality (DEQ), said a cold front from Canada recently moved into North Idaho. Now that the winds have died down, those cold temperatures are setting up inversions – especially in the mountain valleys.

Temperature inversions occur when cold air close to the ground is trapped by a layer of warmer air, which leads to stagnant air and pollution that is trapped close to the ground.

It is now open burning season, which means people can burn on their property without a permit from the Idaho Department of Lands, Sweetwater said. During a temperature inversion, the smoke can get trapped.

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