SmogRank / World / United States / Washington / August 2023
Most polluted cities in Washington, United States, August 2023
46 cities in Washington, United States ranked by their average PM2.5 over the 31 days. Worst: Ephrata at 29.4 µg/m³, #57 of 1,926 cities in the world. Cleanest: Oak Harbor at 4.0. 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.
- 1Ephrata 19%
- 2Moses Lake 16%
- 3Sunnyside 13%
- 4Quincy 13%
- 5Cheney 11%
- 6Walla Walla 10%
- 7Spokane 10%
- 8Mead 10%
- 9Spokane Valley 10%
- 10Airway Heights 10%
- 11Tri-Cities 10%
- 12Prosser 10%
- 13Toppenish 10%
- 14Yakima 10%
- 15Wenatchee 10%
- 16Ellensburg 10%
- 16Finley 10%
- 18Issaquah 7%
- 19Pullman 6%
- 20Auburn 6%
- 21Enumclaw 6%
- 22White Center 3%
- 23Renton 3%
- 24Seattle 3%
- 25Shoreline 3%
- 25Tacoma 3%
- 27Lynden 3%
- 28Parkland 3%
- 29Ridgefield 3%
- 30Bellevue 3%
- 31Bremerton 3%
- 32Chehalis 3%
- 33Vancouver 3%
- 34Mill Plain 3%
- 35Bellingham 0%
- 36Port Angeles 0%
- 37Longview 0%
- 38Shelton 0%
- 39Port Townsend 0%
- 40Aberdeen 0%
- 41Mount Vernon 0%
- 42Lacey 0%
- 43Anacortes 0%
- 44North Bend 0%
- 45Tulalip 0%
- 46Oak Harbor 0%
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, August 2023, smogrank.com/us/region/washington/history/2023-08 (accessed 6 Oct 2026).
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