Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in Indiana

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

Huntington County had the highest share of days with good air quality (US EPA AQI) of 39 counties in 2015, at 98.3%. Montgomery County had the lowest, at 27.1%. The median was 63.6%. Source: EPA.

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Highest98.3Huntington County
Lowest27.1Montgomery County
Median63.639 counties

Map of counties, 2015

Allen County: 49.6 %Bartholomew County: 48.8 %Boone County: 81.8 %Brown County: 91.7 %Carroll County: 84.7 %Clark County: 44 %Delaware County: 78.4 %Dubois County: 53.3 %Elkhart County: 49 %Floyd County: 41.3 %Greene County: 69.1 %Hamilton County: 59.2 %Hancock County: 90.2 %Hendricks County: 97.8 %Henry County: 63.6 %Howard County: 29.2 %Huntington County: 98.3 %Jackson County: 84.4 %Johnson County: 88.3 %Knox County: 90 %Lake County: 38.6 %LaPorte County: 72.8 %Madison County: 55.6 %Marion County: 35.3 %Monroe County: 67.5 %Montgomery County: 27.1 %Morgan County: 89 %Perry County: 80.3 %Porter County: 56.4 %Posey County: 85.2 %St. Joseph County: 42 %Shelby County: 90.7 %Spencer County: 54.8 %Tippecanoe County: 49.1 %Vanderburgh County: 38.9 %Vigo County: 45.6 %Wabash County: 92.2 %Warrick County: 78.1 %Whitley County: 47.4 %
  • Under 43
  • 43 to 49
  • 49 to 64
  • 64 to 81
  • 81 to 90
  • 90 and over
  • No data
%, 2015. 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, 2015

Huntington County: 98.3 %Huntington County98.3Hendricks County: 97.8 %Hendricks County97.8Wabash County: 92.2 %Wabash County92.2Brown County: 91.7 %Brown County91.7Shelby County: 90.7 %Shelby County90.7Hancock County: 90.2 %Hancock County90.2Knox County: 90 %Knox County90Morgan County: 89 %Morgan County89Johnson County: 88.3 %Johnson County88.3Posey County: 85.2 %Posey County85.2Carroll County: 84.7 %Carroll County84.7Jackson County: 84.4 %Jackson County84.4Boone County: 81.8 %Boone County81.8Perry County: 80.3 %Perry County80.3Delaware County: 78.4 %Delaware County78.4Warrick County: 78.1 %Warrick County78.1LaPorte County: 72.8 %LaPorte County72.8Greene County: 69.1 %Greene County69.1Monroe County: 67.5 %Monroe County67.5Henry County: 63.6 %Henry County63.6Hamilton County: 59.2 %Hamilton County59.2Porter County: 56.4 %Porter County56.4Madison County: 55.6 %Madison County55.6Spencer County: 54.8 %Spencer County54.8Dubois County: 53.3 %Dubois County53.3Allen County: 49.6 %Allen County49.6Tippecanoe County: 49.1 %Tippecanoe County49.1Elkhart County: 49 %Elkhart County49Bartholomew County: 48.8 %Bartholomew County48.8Whitley County: 47.4 %Whitley County47.4Vigo County: 45.6 %Vigo County45.6Clark County: 44 %Clark County44St. Joseph County: 42 %St. Joseph County42Floyd County: 41.3 %Floyd County41.3Vanderburgh County: 38.9 %Vanderburgh County38.9Lake County: 38.6 %Lake County38.6Marion County: 35.3 %Marion County35.3Howard County: 29.2 %Howard County29.2Montgomery County: 27.1 %Montgomery County27.1Huntington County: 98.3 %Huntington County98.3Hendricks County: 97.8 %Hendricks County97.8Wabash County: 92.2 %Wabash County92.2Brown County: 91.7 %Brown County91.7Shelby County: 90.7 %Shelby County90.7Hancock County: 90.2 %Hancock County90.2Knox County: 90 %Knox County90Morgan County: 89 %Morgan County89Johnson County: 88.3 %Johnson County88.3Posey County: 85.2 %Posey County85.2Carroll County: 84.7 %Carroll County84.7Jackson County: 84.4 %Jackson County84.4Boone County: 81.8 %Boone County81.8Perry County: 80.3 %Perry County80.3Delaware County: 78.4 %Delaware County78.4Warrick County: 78.1 %Warrick County78.1LaPorte County: 72.8 %LaPorte County72.8Greene County: 69.1 %Greene County69.1Monroe County: 67.5 %Monroe County67.5Henry County: 63.6 %Henry County63.6Hamilton County: 59.2 %Hamilton County59.2Porter County: 56.4 %Porter County56.4Madison County: 55.6 %Madison County55.6Spencer County: 54.8 %Spencer County54.8Dubois County: 53.3 %Dubois County53.3Allen County: 49.6 %Allen County49.6Tippecanoe County: 49.1 %Tippecanoe County49.1Elkhart County: 49 %Elkhart County49Bartholomew County: 48.8 %Bartholomew County48.8Whitley County: 47.4 %Whitley County47.4Vigo County: 45.6 %Vigo County45.6Clark County: 44 %Clark County44St. Joseph County: 42 %St. Joseph County42Floyd County: 41.3 %Floyd County41.3Vanderburgh County: 38.9 %Vanderburgh County38.9Lake County: 38.6 %Lake County38.6Marion County: 35.3 %Marion County35.3Howard County: 29.2 %Howard County29.2Montgomery County: 27.1 %Montgomery County27.1
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2015 (%)Change on 2014
1Huntington County98.3+2.8 pts
2Hendricks County97.8+2.2 pts
3Wabash County92.2+1.7 pts
4Brown County91.7-2.4 pts
5Shelby County90.7+4.4 pts
6Hancock County90.2-8.7 pts
7Knox County90+0.1 pts
8Morgan County89+7.8 pts
9Johnson County88.3-8.3 pts
10Posey County85.2+4 pts
11Carroll County84.7+1.5 pts
12Jackson County84.4+3.2 pts
13Boone County81.8+3.7 pts
14Perry County80.3+5.4 pts
15Delaware County78.4+1.7 pts
16Warrick County78.1+1.6 pts
17LaPorte County72.8+8.8 pts
18Greene County69.1+1.1 pts
19Monroe County67.5+6.8 pts
20Henry County63.6+9.1 pts
21Hamilton County59.2+5.8 pts
22Porter County56.4+20.3 pts
23Madison County55.6+10.5 pts
24Spencer County54.8+8.5 pts
25Dubois County53.3+13.1 pts
26Allen County49.6+18.4 pts
27Tippecanoe County49.1-7.2 pts
28Elkhart County49+26.2 pts
29Bartholomew County48.8-15.5 pts
30Whitley County47.4-1.2 pts
31Vigo County45.6+7.2 pts
32Clark County44+7.3 pts
33St. Joseph County42-1.6 pts
34Floyd County41.3+16.1 pts
35Vanderburgh County38.9+7.1 pts
36Lake County38.6+20.5 pts
37Marion County35.3+12 pts
38Howard County29.2-9.5 pts
39Montgomery County27.1-8.5 pts

Other periods

About this ranking

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.

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. 14 counties with data in other periods have no value for 2015 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: 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 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: good days as a share of days with an AQI, calculated with stored counts (Counties in Indiana by share of days with good air quality (US EPA AQI), 2015) [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: good days as a share of days with an AQI, calculated with stored counts, Counties in Indiana by share of days with good air quality (US EPA AQI), 2015. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/good-air-quality-days-share/indiana-counties. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Counties in Indiana by share of days with good air quality (US EPA AQI), 2015. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/good-air-quality-days-share/indiana-counties.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Counties in Indiana by share of days with good air quality (US EPA AQI), 2015 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/indiana-counties (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_indiana_by_2015,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts: Counties in Indiana by share of days with good air quality (US EPA AQI), 2015}},
  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/good-air-quality-days-share/indiana-counties. Publisher attribution: 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.},
}
RIS
TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts: Counties in Indiana by share of days with good air quality (US EPA AQI), 2015
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/good-air-quality-days-share/indiana-counties
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/indiana-counties.
N1  - Publisher attribution: 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.
ER  -
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Questions

Which county has the highest share of days with good air quality (US EPA AQI)?

Huntington County, with 98.3% in 2015, according to EPA.

Which county has the lowest share of days with good air quality (US EPA AQI)?

Montgomery County, with 27.1% in 2015.

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: good days as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 14 counties have no value for 2015 and are not ranked.

Share of days with good air quality (US EPA AQI): other rankings

Counties in Indiana: more rankings