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.

About 94.7K people in these 9 cities breathed unhealthy air on an average day of August 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.

← Seattle 25.2K 20K0
Every city in Washington, United States ranked for August 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. 1Seattle
    25.2K
  2. 2Tri-Cities
    23.6K
  3. 3Spokane
    22.2K
  4. 4Spokane Valley
    9.19K
  5. 5Yakima
    9.07K
  6. 6Wenatchee
    3.26K
  7. 7Toppenish
    870
  8. 8Mead
    704
  9. 9Finley
    582
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, August 2023 · All cities in United States, August 2023 · Washington now

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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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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.