SmogRank / World / United States / Washington / October 2025

Most polluted cities in Washington, United States, October 2025

48 cities in Washington, United States ranked by their average PM2.5 over the 31 days. Worst: Wenatchee at 20.6 µg/m³, #274 of 2,564 cities in the world. Cleanest: Mount Vernon at 2.4. A city needs measurements on 70% of the days to be ranked.

Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.

← Wenatchee 19% 15%0
Every city in Washington, United States ranked for October 2025, one column each, ranked by unhealthy days: height is the share of its measured days that were unhealthy, colour its average. Point at it to read a city; tap to open it.
  1. 1Wenatchee
    19%
  2. 2Yakima
    0%
  3. 3Toppenish
    0%
  4. 4Picnic Point-North Lynnwood
    0%
  5. 5Anacortes
    0%
  6. 6Vancouver
    0%
  7. 7White Center
    0%
  8. 8Sunnyside
    0%
  9. 9Seattle
    0%
  10. 10Auburn
    0%
  11. 11Spokane
    0%
  12. 12Ellensburg
    0%
  13. 12Spokane Valley
    0%
  14. 14Parkland
    0%
  15. 15Liberty Lake
    0%
  16. 15Prosser
    0%
  17. 15Renton
    0%
  18. 18Lacey
    0%
  19. 18Moses Lake
    0%
  20. 18Port Angeles
    0%
  21. 21Chehalis
    0%
  22. 21Quincy
    0%
  23. 21Tacoma
    0%
  24. 24Columbia Citylow-cost sensors
    0%
  25. 24Lynden
    0%
  26. 24Tri-Cities
    0%
  27. 27Bellingham
    0%
  28. 28Longview
    0%
  29. 28Shoreline
    0%
  30. 30Ephrata
    0%
  31. 30Mead
    0%
  32. 32Burien
    0%
  33. 33Ridgefield
    0%
  34. 33Shelton
    0%
  35. 35North Bend
    0%
  36. 35Pullman
    0%
  37. 37Bremerton
    0%
  38. 37Walla Walla
    0%
  39. 39Airway Heights
    0%
  40. 40Aberdeen
    0%
  41. 41Inglewood-Finn Hilllow-cost sensors
    0%
  42. 42Port Townsend
    0%
  43. 43Bellevue
    0%
  44. 43Kirklandlow-cost sensors
    0%
  45. 45Oak Harbor
    0%
  46. 46Union Hill-Novelty Hilllow-cost sensors
    0%
  47. 47Bothelllow-cost sensors
    0%
  48. 48Mount Vernon
    0%

Low-cost sensors: consumer units, counted only in cities with no government-grade monitor; they read close to reference monitors on the whole, but 15 to 25% high in humid air. How we use them.

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, October 2025 · All cities in United States, October 2025 · Washington now

Use this board

SmogRank, most polluted cities in Washington, United States, PM2.5, October 2025, smogrank.com/us/region/washington/history/2025-10 (accessed 6 Oct 2026).

Download top 10 (PNG)

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.