Smoke: keep one room clean
Shut the windows and run an air purifier sized for the room.
Wildfire smoke guide →Air quality in Washington, county by county
29 Washington counties have enough EPA monitor data to count bad-air days. Weighted by population, they averaged about 5 days a year from 2021 to 2025 when the air was unhealthy for sensitive groups or worse.
CDC's model, which estimates every county from monitors and satellites, gives the average Washington county, weighted by population, about 6 smoky days (fine particles over 35.4 µg/m³, mostly wildfire smoke) and about 1 high-ozone day a year at its worst spot (2018 to 2022). See every county on the map.
Every Washington county with monitors
Most bad-air days first. 14 have a full report. Compare with the worst and the cleanest counties in the US.
| County | Bad-air days a year | |
|---|---|---|
| Chelan CountyWenatcheeSmokeozone not measured | 10.4 | |
| Yakima CountyYakimaSmokeozone not measured | 9.4 | |
| Okanogan CountySmokeozone not measured | 9.0 | |
| Asotin CountySmokeozone not measured | 8.2 | |
| Stevens CountySmokeozone not measured | 8.2 | |
| King CountySeattleSummer smoke | 6.6 | |
| Snohomish CountyEverettSmokeozone not measured | 6.0 | |
| Spokane CountySpokaneSummer smoke | 4.6 | |
| Benton CountyKennewickOzone and particles | 4.2 | |
| Grant CountyMoses LakeSmokeozone not measured | 3.6 | |
| Kittitas CountyEllensburgSmokeozone not measured | 3.4 | |
| Whitman CountyPullmanSmokeozone not measured | 3.2 | |
| Columbia CountySummer smoke | 3.0 | |
| Pierce CountyTacomaSummer smoke | 3.0 | |
| Adams CountyOthelloSmokeozone not measured | 2.8 | |
| Lewis CountyCentraliaSmokeozone not measured | 2.6 | |
| Garfield CountySmokeozone not measured | 2.4 | |
| Walla Walla CountyWalla WallaSmokeozone not measured | 2.4 | |
| Whatcom CountyBellinghamSummer smoke | 2.4 | |
| Franklin CountySmokeozone not measured | 2.0 | |
| Clark CountyVancouverSummer smoke | 1.6 | |
| Skagit CountyMount VernonSummer smoke | 1.2 | |
| Kitsap CountyBremertonSmokeozone not measured | 1.0 | |
| Mason CountySheltonSmokeozone not measured | 1.0 | |
| Clallam CountyPort AngelesSummer smoke | 0.6 | |
| Thurston CountyLaceySummer smoke | 0.6 | |
| Cowlitz CountyLongviewRarely badozone not measured | 0.4 | |
| Grays Harbor CountyAberdeenRarely badozone not measured | 0.2 | |
| Jefferson CountyPort TownsendRarely badozone not measured | 0.0 | |
| No Washington county with a monitor matches “”. Counties without a monitor aren't listed; a neighbor's numbers are a fair guide, or find it on the map. | ||
Counties without a monitor aren't listed. Air doesn't stop at the county line, so a neighbor's numbers are a fair guide.
What helps on a bad-air day
Check AirNow for today's reading and tomorrow's forecast, then match the step to the pollutant.
Upgrade the furnace filter
MERV 13 catches far more smoke than thin fiberglass filters.
Furnace filters →Questions people ask about air quality in Washington
Which county in Washington has the worst air?
Among Washington counties with EPA monitors, Chelan County had the most bad-air days from 2021 to 2025: about 10 bad-air days a year with an AQI over 100. That's about 1 day in 35.
How often is the air bad in Washington?
Weighted by population, Washington counties with monitors averaged about 5 bad-air days a year from 2021 to 2025 with an AQI over 100, when children, older adults and people with asthma should cut back outdoors. That's about 1 day in 81.
Which county in Washington has the cleanest air?
Of the 29 counties with enough monitor data, Jefferson County had the fewest, with no bad-air days at all from 2021 to 2025. Counties without monitors aren't ranked.
Where can I check today's air quality in Washington?
AirNow, run by the EPA and its partners, shows current readings and forecasts by ZIP code, and its fire and smoke map adds smoke plumes and low-cost sensors.
Sources: EPA AirData county AQI summaries, 2021 to 2025; CDC Environmental Public Health Tracking Network modeled PM2.5 and ozone, 2018 to 2022. Updated November 8, 2026.