SmogRank / World / United States / Washington / May 2026

Most polluted cities in Washington, United States, May 2026

48 cities in Washington, United States ranked by their average PM2.5 over the 31 days. Worst: Redmond at 9.3 µg/m³, #920 of 2,852 cities in the world. Cleanest: Union Hill-Novelty Hill at 2.1. 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.

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

All cities in the world, May 2026 · All cities in United States, May 2026 · Washington now

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SmogRank, most polluted cities in Washington, United States, PM2.5, May 2026, smogrank.com/us/region/washington/history/2026-05 (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.