SmogRank / World / United States / Washington / September 2026

Most polluted cities in Washington, United States, September 2026

56 cities in Washington, United States ranked by their average PM2.5 over the 30 days. Worst: Sunnyside at 8.6 µg/m³, #852 of 2,949 cities in the world. Cleanest: Kirkland at 2.9. 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.

← Sunnyside 0% 0.75%0
Every city in Washington, United States ranked for September 2026, 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. 1Sunnyside
    0%
  2. 2Vancouver
    0%
  3. 3Renton
    0%
  4. 4Airway Heights
    0%
  5. 5White Center
    0%
  6. 6Tacoma
    0%
  7. 6Wenatchee
    0%
  8. 8Seattle
    0%
  9. 9Grandview
    0%
  10. 10Auburn
    0%
  11. 10Bellingham
    0%
  12. 10Toppenish
    0%
  13. 13Kent
    0%
  14. 13Prosser
    0%
  15. 15Union Gap
    0%
  16. 16Bremerton
    0%
  17. 17Moses Lake
    0%
  18. 17Pullman
    0%
  19. 19Quincy
    0%
  20. 19Spokane Valley
    0%
  21. 21Ellensburg
    0%
  22. 21Shoreline
    0%
  23. 21Yakima
    0%
  24. 24Port Angeles
    0%
  25. 24Tulalip
    0%
  26. 26Burien
    0%
  27. 26North Bend
    0%
  28. 28Fairwood
    0%
  29. 28Spokane
    0%
  30. 28Walla Walla
    0%
  31. 31Longview
    0%
  32. 31Lynden
    0%
  33. 31Mead
    0%
  34. 34Chehalis
    0%
  35. 34Liberty Lake
    0%
  36. 34Parkland
    0%
  37. 34Ridgefield
    0%
  38. 38Aberdeen
    0%
  39. 38Lacey
    0%
  40. 40Bellevue
    0%
  41. 40Finley
    0%
  42. 42Ephrata
    0%
  43. 43Port Townsend
    0%
  44. 43Shelton
    0%
  45. 43Tri-Cities
    0%
  46. 46Cheney
    0%
  47. 47Picnic Point-North Lynnwood
    0%
  48. 48Mount Vernon
    0%
  49. 49Inglewood-Finn Hilllow-cost sensors
    0%
  50. 50Monroelow-cost sensors
    0%
  51. 51Columbia Citylow-cost sensors
    0%
  52. 52Bothelllow-cost sensors
    0%
  53. 53Anacortes
    0%
  54. 53North Creeklow-cost sensors
    0%
  55. 53Union Hill-Novelty Hilllow-cost sensors
    0%
  56. 56Kirklandlow-cost sensors
    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

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SmogRank, most polluted cities in Washington, United States, PM2.5, September 2026, smogrank.com/us/region/washington/history/2026-09 (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.