# Counties in Iowa by share of days with good air quality (US EPA AQI), 2016

All 19 values come from U.S. Environmental Protection Agency for 2016, so the places are comparable. 7 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/iowa-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Cerro Gordo County | 98.9 |
| 2 | Warren County | 95.8 |
| 3 | Story County | 93.4 |
| 4 | Bremer County | 92 |
| 5 | Harrison County | 88.7 |
| 6 | Pottawattamie County | 77.4 |
| 7 | Delaware County | 77.3 |
| 8 | Woodbury County | 75.6 |
| 9 | Polk County | 66.7 |
| 10 | Palo Alto County | 65 |
| 11 | Johnson County | 64.5 |
| 12 | Montgomery County | 63.4 |
| 13 | Lee County | 62.8 |
| 14 | Linn County | 53.8 |
| 15 | Muscatine County | 51.4 |
| 16 | Black Hawk County | 49.2 |
| 17 | Van Buren County | 48.4 |
| 18 | Clinton County | 25.1 |
| 19 | Scott County | 16.9 |