Air quality · Washington
Air quality in Washington
Across the 11 Washington ZIPs with EPA county air-quality data, the median day is Good in all 11 (median AQI 31–43). 1 day across those counties reached Unhealthy or worse in 2025. This is a 2025 county annual summary, not a live reading.
Last verified 2026-09-24 · methodology
Air quality by ZIP code in Washington
EPA's 2025 annual summary for each ZIP's county. Median AQI is the typical day; lower is cleaner.
| ZIP | Median AQI | Good days | Unhealthy or worse |
|---|---|---|---|
| 98101SeattleKing County | 43 Good | 245 of 365 | 0 |
| 98109Seattle (Queen Anne)King County | 43 Good | 245 of 365 | 0 |
| 98033KirklandKing County | 43 Good | 245 of 365 | 0 |
| 99201SpokaneSpokane County | 43 Good | 236 of 365 | 0 |
| 98225BellinghamWhatcom County | 31 Good | 342 of 364 | 1 |
| 98115Seattle (Wallingford)King County | 43 Good | 245 of 365 | 0 |
| 98662Vancouver (WA)Clark County | 33 Good | 302 of 365 | 0 |
| 98052Redmond (WA)King County | 43 Good | 245 of 365 | 0 |
| 98039Medina (WA)King County | 43 Good | 245 of 365 | 0 |
| 98004Bellevue (WA)King County | 43 Good | 245 of 365 | 0 |
| 98112Seattle (Capitol Hill)King County | 43 Good | 245 of 365 | 0 |
County-level figures from EPA Air Quality System (AQS), annual county summary, joined to each ZIP by county. None of them is a measurement at a specific address.
What lands here
Pages show the 2025 median AQI category (Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, Hazardous) for the ZIP's county, plus the year's max/90th-percentile AQI and day-count breakdown by category.
Source & refresh
EPA Air Quality System (AQS), annual county summary. Refreshed annual (epa aqs publication). Primary source →
Washington top concern
Wildfire (eastern), Cascadia seismic, coastal flood
Washington's wildfire risk concentrates in eastern WA + the Cascades. Cascadia subduction zone shapes long-term seismic risk. Puget Sound coastal flood zones face Risk Rating 2.0 pressure. Seattle has documented LCRR lead-service-line obligations.
See Washington state page for the full state-level rollup across all 12 dimensions.
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Editorial deep-dives explaining the source data, its limits, and how to read it.
EPA AQI categories explained — what 0–50 Good through 301–500 Hazardous mean
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AQI explained — what 50, 100, 150 actually mean for your lungs
Plain-English guide to the EPA Air Quality Index (AQI) and the 6 categories from Good to Hazardous. When to take precautions and which pollutants matter.
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AirNow + wildfire smoke — when AQI is a real-time tool
How EPA AirNow handles real-time wildfire smoke, what the colors mean during fire season, and where AirNow leaves gaps you should know about.