# Counties in Ohio by share of days with good air quality (US EPA AQI), 2001

All 45 values come from U.S. Environmental Protection Agency for 2001, so the places are comparable. 13 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/ohio-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Hancock County | 100 |
| 1 | Ottawa County | 100 |
| 1 | Sandusky County | 100 |
| 4 | Belmont County | 98.3 |
| 5 | Seneca County | 97.7 |
| 6 | Wyandot County | 97.6 |
| 7 | Monroe County | 96.6 |
| 8 | Columbiana County | 94.1 |
| 9 | Fayette County | 76.9 |
| 10 | Crawford County | 74.7 |
| 11 | Allen County | 71 |
| 12 | Wood County | 69.6 |
| 13 | Ashtabula County | 65.4 |
| 14 | Washington County | 65.2 |
| 15 | Noble County | 64.2 |
| 16 | Warren County | 64 |
| 17 | Licking County | 62.9 |
| 18 | Lake County | 62.5 |
| 19 | Greene County | 62 |
| 20 | Medina County | 60.3 |
| 21 | Clermont County | 60.1 |
| 22 | Knox County | 59.8 |
| 23 | Madison County | 57.9 |
| 24 | Lorain County | 57.4 |
| 25 | Miami County | 56.5 |
| 26 | Geauga County | 55.6 |
| 27 | Scioto County | 55.2 |
| 28 | Delaware County | 54.9 |
| 29 | Clinton County | 54.2 |
| 29 | Stark County | 54.2 |
| 31 | Preble County | 53.7 |
| 32 | Portage County | 46.4 |
| 33 | Athens County | 43 |
| 34 | Clark County | 42.1 |
| 35 | Lawrence County | 39.9 |
| 36 | Lucas County | 22.2 |
| 37 | Trumbull County | 20.9 |
| 38 | Montgomery County | 20.3 |
| 39 | Mahoning County | 20.1 |
| 40 | Butler County | 18.9 |
| 41 | Jefferson County | 17.5 |
| 41 | Summit County | 17.5 |
| 43 | Franklin County | 15.9 |
| 44 | Cuyahoga County | 12.9 |
| 45 | Hamilton County | 11.2 |