The National Weather Service (NWS) has issued Air Stagnation Advisories across four cities, warning of deteriorating air quality due to stagnant atmospheric conditions trapping pollutants near the surface. The advisories impact large areas of Idaho, Oregon, Montana and Washington, lasting through the end of January.

What Is An Air Stagnation Advisory?

The NWS says an air stagnation advisory “is issued when major buildups of air pollution, smoke, dust, or industrial gases are expected near the ground for a period of time. This usually results from a stagnant high pressure system, with weak winds being unable to bring in fresh air.”

Why It Matters

Air stagnation can significantly impact air quality, leading to increased health risks for individuals with asthma, chronic respiratory diseases, and other underlying conditions. Extended exposure to polluted air can cause irritation of the eyes, nose, and throat and may exacerbate existing health issues.

Idaho

The NWS Boise office issued an Air Stagnation Advisory alongside a Cold Weather Advisory, affecting south-central, southwest, and west-central Idaho. The advisory, in effect until January 31, 2025, highlights concerns over trapped pollutants leading to poor air quality. Areas impacted include the Camas Prairie, West Central Mountains, Lower Treasure Valley, Boise Mountains, and several other regions.

Additionally, a Cold Weather Advisory for the Camas Prairie remains active until January 29, warning residents of potentially hazardous cold conditions. Meteorologists cite an inversion near the surface as the primary cause for the stagnation, which can exacerbate respiratory issues for vulnerable populations.

Oregon

NWS Pendleton issued an Air Stagnation Advisory covering large portions of central, north-central, and northeast Oregon. The advisory, lasting until January 31 at 4 a.m. PST, includes affected areas such as the Eastern Columbia River Gorge, Lower Columbia Basin, and the Blue Mountains’ foothills.

Montana

NWS Missoula has issued an Air Stagnation Advisory for several regions in Montana, including the Lower Clark Fork Region, Missoula/Bitterroot Valleys, Potomac/Seeley Lake Region, and Kootenai/Cabinet Region. The advisory, effective from January 25 to January 31, highlights concerns about accumulating pollutants and deteriorating air quality.

Washington

NWS Spokane issued an Air Stagnation Advisory for a broad section of Washington, including the Lewiston Area, Spokane Area, Okanogan Highlands, Wenatchee Area, and Central Panhandle Mountains. The advisory is set to expire on January 31 at 4 a.m. PST.

The stagnant conditions in Washington are expected to cause pollutants to accumulate near the surface, impacting air quality. Authorities recommend that residents limit activities that contribute to air pollution, such as burning wood or unnecessary vehicle use, to mitigate worsening conditions.

What’s Next

The advisories are expected to remain in effect until January 31, with meteorologists closely monitoring weather patterns for potential changes. Residents in affected areas should stay updated on local air quality reports and follow guidance from health and environmental agencies to minimize exposure to poor air conditions.