SmogRank / World / United States / Washington / 2023

Most polluted cities in Washington, United States, 2023

44 cities in Washington, United States ranked by their average PM2.5 over the 365 days; 31 above the WHO annual guideline (5.0 µg/m³). Worst: Sunnyside at 9.7 µg/m³, #515 of 1,302 cities in the world. Cleanest: Tulalip at 1.9. A city needs measurements on 70% of the days to be ranked.

OpenAQ's archive, where our readings come from, has almost none for 56 of these 365 days. Cities in the United States and Europe have them from the EPA's and the European Environment Agency's own records of the same monitors; elsewhere a city's average is over its other days. Why.

About 9.05K people in these 9 cities breathed unhealthy air on an average day of 2023.

Ranked by people: each city's population times its share of unhealthy days, those with a daily mean over 35.4 µg/m³ (US AQI 101+). That is how many people living there breathed unhealthy air on an average day. Only cities measured at 2 or more places at least 3 km apart are ranked: one monitor shouldn't speak for a whole city. Population is the city itself, not its wider metro area.

← Tri-Cities 2.39K 2K0
Every city in Washington, United States ranked for 2023 with monitors in two or more places, one column each, ranked by people breathing unhealthy air: height is people on an average day, colour its average. Point at it to read a city; tap to open it.
  1. 1Tri-Cities
    2.39K
  2. 2Spokane
    2.37K
  3. 3Seattle
    2.16K
  4. 4Spokane Valley
    800
  5. 5Yakima
    796
  6. 6Wenatchee
    329
  7. 7Toppenish
    88
  8. 8Mead
    71
  9. 9Finley
    59
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales

All cities in the world, 2023 · All cities in United States, 2023 · Washington now

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SmogRank, most polluted cities in Washington, United States, PM2.5, 2023, smogrank.com/us/region/washington/history/2023 (accessed 6 Oct 2026).

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.