Data / Rankings / Share of days unhealthy for sensitive groups or worse (US EPA AQI) / Counties in Indiana

Counties in Indiana by share of days unhealthy for sensitive groups or worse (US EPA AQI)

Hendricks County had the highest share of days unhealthy for sensitive groups or worse (US EPA AQI) of 40 counties in 2000, at 26.5%. Wayne County had the lowest, at 0%. The median was 4.8%. Source: EPA.

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Highest26.5Hendricks County
Lowest0Wayne County
Median4.840 counties

Map of counties, 2000

Allen County: 4.4 %Bartholomew County: 0 %Boone County: 7.1 %Clark County: 12.2 %Daviess County: 0 %DeKalb County: 0 %Delaware County: 1.8 %Dubois County: 5.1 %Elkhart County: 2.7 %Floyd County: 6.3 %Gibson County: 0.5 %Greene County: 8 %Hamilton County: 7.7 %Hancock County: 7.1 %Hendricks County: 26.5 %Henry County: 0 %Howard County: 0.9 %Huntington County: 5.9 %Jackson County: 7.8 %Jasper County: 0 %Johnson County: 7.7 %Knox County: 3.4 %Lake County: 9.3 %LaPorte County: 3.3 %Madison County: 5.4 %Marion County: 7.9 %Morgan County: 8.8 %Perry County: 14.6 %Porter County: 3.8 %Posey County: 14.2 %Putnam County: 0 %St. Joseph County: 3.6 %Shelby County: 9.9 %Spencer County: 1.4 %Tippecanoe County: 0.9 %Vanderburgh County: 6.6 %Vigo County: 3.7 %Wabash County: 3.6 %Warrick County: 8.7 %Wayne County: 0 %
  • Under 0.3
  • 0.3 to 3.3
  • 3.3 to 4.8
  • 4.8 to 7.1
  • 7.1 to 8.8
  • 8.8 and over
  • No data
%, 2000. Hatched areas have no value for this period. Source: Invokely calculation with data from EPA. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2000

Hendricks County: 26.5 %Hendricks County26.5Perry County: 14.6 %Perry County14.6Posey County: 14.2 %Posey County14.2Clark County: 12.2 %Clark County12.2Shelby County: 9.9 %Shelby County9.9Lake County: 9.3 %Lake County9.3Morgan County: 8.8 %Morgan County8.8Warrick County: 8.7 %Warrick County8.7Greene County: 8 %Greene County8Marion County: 7.9 %Marion County7.9Jackson County: 7.8 %Jackson County7.8Hamilton County: 7.7 %Hamilton County7.7Johnson County: 7.7 %Johnson County7.7Boone County: 7.1 %Boone County7.1Hancock County: 7.1 %Hancock County7.1Vanderburgh County: 6.6 %Vanderburgh County6.6Floyd County: 6.3 %Floyd County6.3Huntington County: 5.9 %Huntington County5.9Madison County: 5.4 %Madison County5.4Dubois County: 5.1 %Dubois County5.1Allen County: 4.4 %Allen County4.4Porter County: 3.8 %Porter County3.8Vigo County: 3.7 %Vigo County3.7St. Joseph County: 3.6 %St. Joseph County3.6Wabash County: 3.6 %Wabash County3.6Knox County: 3.4 %Knox County3.4LaPorte County: 3.3 %LaPorte County3.3Elkhart County: 2.7 %Elkhart County2.7Delaware County: 1.8 %Delaware County1.8Spencer County: 1.4 %Spencer County1.4Howard County: 0.9 %Howard County0.9Tippecanoe County: 0.9 %Tippecanoe County0.9Gibson County: 0.5 %Gibson County0.5Bartholomew County: 0 %Bartholomew County0Daviess County: 0 %Daviess County0DeKalb County: 0 %DeKalb County0Henry County: 0 %Henry County0Jasper County: 0 %Jasper County0Putnam County: 0 %Putnam County0Wayne County: 0 %Wayne County0Hendricks County: 26.5 %Hendricks County26.5Perry County: 14.6 %Perry County14.6Posey County: 14.2 %Posey County14.2Clark County: 12.2 %Clark County12.2Shelby County: 9.9 %Shelby County9.9Lake County: 9.3 %Lake County9.3Morgan County: 8.8 %Morgan County8.8Warrick County: 8.7 %Warrick County8.7Greene County: 8 %Greene County8Marion County: 7.9 %Marion County7.9Jackson County: 7.8 %Jackson County7.8Hamilton County: 7.7 %Hamilton County7.7Johnson County: 7.7 %Johnson County7.7Boone County: 7.1 %Boone County7.1Hancock County: 7.1 %Hancock County7.1Vanderburgh County: 6.6 %Vanderburgh County6.6Floyd County: 6.3 %Floyd County6.3Huntington County: 5.9 %Huntington County5.9Madison County: 5.4 %Madison County5.4Dubois County: 5.1 %Dubois County5.1Allen County: 4.4 %Allen County4.4Porter County: 3.8 %Porter County3.8Vigo County: 3.7 %Vigo County3.7St. Joseph County: 3.6 %St. Joseph County3.6Wabash County: 3.6 %Wabash County3.6Knox County: 3.4 %Knox County3.4LaPorte County: 3.3 %LaPorte County3.3Elkhart County: 2.7 %Elkhart County2.7Delaware County: 1.8 %Delaware County1.8Spencer County: 1.4 %Spencer County1.4Howard County: 0.9 %Howard County0.9Tippecanoe County: 0.9 %Tippecanoe County0.9Gibson County: 0.5 %Gibson County0.5Bartholomew County: 0 %Bartholomew County0Daviess County: 0 %Daviess County0DeKalb County: 0 %DeKalb County0Henry County: 0 %Henry County0Jasper County: 0 %Jasper County0Putnam County: 0 %Putnam County0Wayne County: 0 %Wayne County0
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2000 (%)Change on 1999
1Hendricks County26.5-4.6 pts
2Perry County14.6-4.9 pts
3Posey County14.2-6.6 pts
4Clark County12.2-3.4 pts
5Shelby County9.9n/a
6Lake County9.3-6.6 pts
7Morgan County8.8-15.2 pts
8Warrick County8.7-14.3 pts
9Greene County8n/a
10Marion County7.9-7.7 pts
11Jackson County7.8n/a
12Hamilton County7.7-18.3 pts
12Johnson County7.7-15.8 pts
14Boone County7.1n/a
14Hancock County7.1-18.7 pts
16Vanderburgh County6.6-6.6 pts
17Floyd County6.3-11.3 pts
18Huntington County5.9n/a
19Madison County5.4-15.6 pts
20Dubois County5.1+5.1 pts
21Allen County4.4-6 pts
22Porter County3.8-8.3 pts
23Vigo County3.7-5.9 pts
24St. Joseph County3.6-9.9 pts
24Wabash County3.6-8.3 pts
26Knox County3.4-8 pts
27LaPorte County3.3-14 pts
28Elkhart County2.7-2.7 pts
29Delaware County1.8+1.8 pts
30Spencer County1.4+1.4 pts
31Howard County0.9-2.6 pts
31Tippecanoe County0.9-0.5 pts
33Gibson County0.5-2.8 pts
34Bartholomew County0n/a
34Daviess County0n/a
34DeKalb County00 pts
34Henry County0n/a
34Jasper County00 pts
34Putnam County0n/a
34Wayne County0n/a

Other periods

About this ranking

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.

Use the share rather than the number of days to compare counties, since the days with an AQI differ. United States counties with air quality monitors only, about 1,000 of some 3,100 in recent years; a county without monitors has no value. The number of days with an AQI differs between counties because some monitors run only in the ozone season.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. 13 counties with data in other periods have no value for 2000 and are left out rather than filled from another source. Equal values share a rank.

How to cite

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.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Environmental Protection Agency. (2026). EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts (Counties in Indiana by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2000) [Data set]. Retrieved October 12, 2026, from https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual

MLA 9

EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts, Counties in Indiana by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2000. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/indiana-counties?period=2000. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts. Counties in Indiana by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2000. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/indiana-counties?period=2000.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts, Counties in Indiana by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2000 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/unhealthy-air-quality-days-share/indiana-counties?period=2000 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_indiana_by_2000,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts: Counties in Indiana by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2000}},
  year = {2026},
  howpublished = {Data set},
  url = {https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/indiana-counties?period=2000. Publisher attribution: 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.},
}
RIS
TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts: Counties in Indiana by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2000
PY  - 2026
DA  - 2026/07/13
PB  - U.S. Environmental Protection Agency
DB  - Invokely
UR  - https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual
L2  - https://invokely.ai/rankings/unhealthy-air-quality-days-share/indiana-counties?period=2000
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/indiana-counties?period=2000.
N1  - Publisher attribution: 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.
ER  -
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Rank Counties in Indiana by share of days unhealthy for sensitive groups or worse (US EPA AQI) using official data, and cite the source.
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Questions

Which county has the highest share of days unhealthy for sensitive groups or worse (US EPA AQI)?

Hendricks County, with 26.5% in 2000, according to EPA.

Which county has the lowest share of days unhealthy for sensitive groups or worse (US EPA AQI)?

Wayne County, with 0% in 2000.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: 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. Retrieved 2026-10-12. 13 counties have no value for 2000 and are not ranked.

Share of days unhealthy for sensitive groups or worse (US EPA AQI): other rankings

Counties in Indiana: more rankings