# Counties in Indiana by share of days with good air quality (US EPA AQI), 2015

All 39 values come from U.S. Environmental Protection Agency for 2015, so the places are comparable. 14 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/indiana-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Huntington County | 98.3 |
| 2 | Hendricks County | 97.8 |
| 3 | Wabash County | 92.2 |
| 4 | Brown County | 91.7 |
| 5 | Shelby County | 90.7 |
| 6 | Hancock County | 90.2 |
| 7 | Knox County | 90 |
| 8 | Morgan County | 89 |
| 9 | Johnson County | 88.3 |
| 10 | Posey County | 85.2 |
| 11 | Carroll County | 84.7 |
| 12 | Jackson County | 84.4 |
| 13 | Boone County | 81.8 |
| 14 | Perry County | 80.3 |
| 15 | Delaware County | 78.4 |
| 16 | Warrick County | 78.1 |
| 17 | LaPorte County | 72.8 |
| 18 | Greene County | 69.1 |
| 19 | Monroe County | 67.5 |
| 20 | Henry County | 63.6 |
| 21 | Hamilton County | 59.2 |
| 22 | Porter County | 56.4 |
| 23 | Madison County | 55.6 |
| 24 | Spencer County | 54.8 |
| 25 | Dubois County | 53.3 |
| 26 | Allen County | 49.6 |
| 27 | Tippecanoe County | 49.1 |
| 28 | Elkhart County | 49 |
| 29 | Bartholomew County | 48.8 |
| 30 | Whitley County | 47.4 |
| 31 | Vigo County | 45.6 |
| 32 | Clark County | 44 |
| 33 | St. Joseph County | 42 |
| 34 | Floyd County | 41.3 |
| 35 | Vanderburgh County | 38.9 |
| 36 | Lake County | 38.6 |
| 37 | Marion County | 35.3 |
| 38 | Howard County | 29.2 |
| 39 | Montgomery County | 27.1 |