# Counties in Indiana by share of days unhealthy for sensitive groups or worse (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_unhealthy_sensitive_or_worse_days_share`
- Unit: %
- Definition: Days with a daily Air Quality Index above 100 (unhealthy for sensitive groups, unhealthy, very unhealthy or hazardous) 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; the counts are stored with each value.
- Source: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: days with an AQI above 100 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: days with an AQI above 100 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/unhealthy-air-quality-days-share/indiana-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Lake County | 1.6 |
| 1 | Vanderburgh County | 1.6 |
| 3 | LaPorte County | 1.2 |
| 4 | Clark County | 1.1 |
| 4 | Perry County | 1.1 |
| 4 | Porter County | 1.1 |
| 4 | Posey County | 1.1 |
| 4 | Warrick County | 1.1 |
| 9 | Elkhart County | 0.8 |
| 9 | Greene County | 0.8 |
| 9 | Marion County | 0.8 |
| 12 | Allen County | 0.6 |
| 12 | Brown County | 0.6 |
| 12 | Floyd County | 0.6 |
| 12 | Jackson County | 0.6 |
| 12 | St. Joseph County | 0.6 |
| 12 | Wabash County | 0.6 |
| 18 | Bartholomew County | 0.5 |
| 19 | Delaware County | 0.4 |
| 20 | Howard County | 0.3 |
| 20 | Vigo County | 0.3 |
| 22 | Boone County | 0 |
| 22 | Carroll County | 0 |
| 22 | Dubois County | 0 |
| 22 | Hamilton County | 0 |
| 22 | Hancock County | 0 |
| 22 | Hendricks County | 0 |
| 22 | Henry County | 0 |
| 22 | Huntington County | 0 |
| 22 | Johnson County | 0 |
| 22 | Knox County | 0 |
| 22 | Madison County | 0 |
| 22 | Monroe County | 0 |
| 22 | Montgomery County | 0 |
| 22 | Morgan County | 0 |
| 22 | Shelby County | 0 |
| 22 | Spencer County | 0 |
| 22 | Tippecanoe County | 0 |
| 22 | Whitley County | 0 |