# Counties in Washington by share of days with good air quality (US EPA AQI), 2025

All 31 values come from U.S. Environmental Protection Agency for 2025, so the places are comparable. 3 counties have no value for that period and are not ranked.

- Indicator id: `aqi_good_days_share`
- Unit: %
- Definition: Days with a daily Air Quality Index of 0 to 50 (good) as a percentage of the days of the year with an AQI in a US county. Calculated by Invokely from the day counts in the EPA AirData annual summaries; both counts are stored with each value.
- Source: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts (https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual)
- Retrieved: 2026-10-12
- Citation: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
- Web page: https://invokely.ai/rankings/good-air-quality-days-share/washington-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Pacific County | 99.7 |
| 2 | Skagit County | 97.5 |
| 3 | Grays Harbor County | 97.3 |
| 3 | Jefferson County | 97.3 |
| 5 | Kitsap County | 95.5 |
| 6 | Whatcom County | 94 |
| 7 | Thurston County | 93.5 |
| 8 | Garfield County | 92.5 |
| 9 | Lewis County | 91.3 |
| 10 | Adams County | 90.5 |
| 11 | Columbia County | 90.4 |
| 11 | Cowlitz County | 90.4 |
| 11 | Mason County | 90.4 |
| 14 | Whitman County | 86.8 |
| 15 | Franklin County | 86.7 |
| 16 | Clallam County | 85.5 |
| 17 | Klickitat County | 84.6 |
| 18 | Clark County | 82.7 |
| 19 | Walla Walla County | 80.8 |
| 20 | Benton County | 80.3 |
| 21 | Kittitas County | 80 |
| 22 | Grant County | 79.7 |
| 23 | Pierce County | 73.2 |
| 24 | Chelan County | 69.6 |
| 25 | Stevens County | 69 |
| 26 | Snohomish County | 67.9 |
| 27 | King County | 67.1 |
| 28 | Spokane County | 64.7 |
| 29 | Asotin County | 61.9 |
| 29 | Yakima County | 61.9 |
| 31 | Okanogan County | 56.5 |