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)

Daviess County had the highest share of days with good air quality (US EPA AQI) of 40 counties in 2003, at 100%. Marion County had the lowest, at 11%. The median was 51.2%. Source: EPA.

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Highest100Daviess County
Lowest11Marion County
Median51.240 counties

Map of counties, 2003

Allen County: 36.4 %Boone County: 50.3 %Carroll County: 62.8 %Clark County: 51 %Daviess County: 100 %Delaware County: 47.2 %Dubois County: 25.4 %Elkhart County: 44.4 %Floyd County: 47.1 %Gibson County: 84.2 %Greene County: 50.8 %Hamilton County: 54.1 %Hancock County: 53.6 %Hendricks County: 69.1 %Henry County: 35 %Howard County: 33.6 %Huntington County: 54.1 %Jackson County: 54.1 %Johnson County: 51.9 %Knox County: 64.2 %Kosciusko County: 52.9 %Lake County: 15.9 %LaPorte County: 46.3 %Madison County: 42.3 %Marion County: 11 %Morgan County: 51.4 %Perry County: 96.7 %Porter County: 63.1 %Posey County: 59.6 %Putnam County: 96.6 %St. Joseph County: 34.5 %Shelby County: 54.1 %Spencer County: 26.4 %Tippecanoe County: 30.8 %Vanderburgh County: 39.2 %Vigo County: 47.5 %Wabash County: 79.3 %Warrick County: 51.9 %Washington County: 42.5 %Whitley County: 91.9 %
  • Under 35
  • 35 to 46
  • 46 to 51
  • 51 to 54
  • 54 to 67
  • 67 and over
  • No data
%, 2003. 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, 2003

Daviess County: 100 %Daviess County100Perry County: 96.7 %Perry County96.7Putnam County: 96.6 %Putnam County96.6Whitley County: 91.9 %Whitley County91.9Gibson County: 84.2 %Gibson County84.2Wabash County: 79.3 %Wabash County79.3Hendricks County: 69.1 %Hendricks County69.1Knox County: 64.2 %Knox County64.2Porter County: 63.1 %Porter County63.1Carroll County: 62.8 %Carroll County62.8Posey County: 59.6 %Posey County59.6Hamilton County: 54.1 %Hamilton County54.1Huntington County: 54.1 %Huntington County54.1Jackson County: 54.1 %Jackson County54.1Shelby County: 54.1 %Shelby County54.1Hancock County: 53.6 %Hancock County53.6Kosciusko County: 52.9 %Kosciusko County52.9Johnson County: 51.9 %Johnson County51.9Warrick County: 51.9 %Warrick County51.9Morgan County: 51.4 %Morgan County51.4Clark County: 51 %Clark County51Greene County: 50.8 %Greene County50.8Boone County: 50.3 %Boone County50.3Vigo County: 47.5 %Vigo County47.5Delaware County: 47.2 %Delaware County47.2Floyd County: 47.1 %Floyd County47.1LaPorte County: 46.3 %LaPorte County46.3Elkhart County: 44.4 %Elkhart County44.4Washington County: 42.5 %Washington County42.5Madison County: 42.3 %Madison County42.3Vanderburgh County: 39.2 %Vanderburgh County39.2Allen County: 36.4 %Allen County36.4Henry County: 35 %Henry County35St. Joseph County: 34.5 %St. Joseph County34.5Howard County: 33.6 %Howard County33.6Tippecanoe County: 30.8 %Tippecanoe County30.8Spencer County: 26.4 %Spencer County26.4Dubois County: 25.4 %Dubois County25.4Lake County: 15.9 %Lake County15.9Marion County: 11 %Marion County11Daviess County: 100 %Daviess County100Perry County: 96.7 %Perry County96.7Putnam County: 96.6 %Putnam County96.6Whitley County: 91.9 %Whitley County91.9Gibson County: 84.2 %Gibson County84.2Wabash County: 79.3 %Wabash County79.3Hendricks County: 69.1 %Hendricks County69.1Knox County: 64.2 %Knox County64.2Porter County: 63.1 %Porter County63.1Carroll County: 62.8 %Carroll County62.8Posey County: 59.6 %Posey County59.6Hamilton County: 54.1 %Hamilton County54.1Huntington County: 54.1 %Huntington County54.1Jackson County: 54.1 %Jackson County54.1Shelby County: 54.1 %Shelby County54.1Hancock County: 53.6 %Hancock County53.6Kosciusko County: 52.9 %Kosciusko County52.9Johnson County: 51.9 %Johnson County51.9Warrick County: 51.9 %Warrick County51.9Morgan County: 51.4 %Morgan County51.4Clark County: 51 %Clark County51Greene County: 50.8 %Greene County50.8Boone County: 50.3 %Boone County50.3Vigo County: 47.5 %Vigo County47.5Delaware County: 47.2 %Delaware County47.2Floyd County: 47.1 %Floyd County47.1LaPorte County: 46.3 %LaPorte County46.3Elkhart County: 44.4 %Elkhart County44.4Washington County: 42.5 %Washington County42.5Madison County: 42.3 %Madison County42.3Vanderburgh County: 39.2 %Vanderburgh County39.2Allen County: 36.4 %Allen County36.4Henry County: 35 %Henry County35St. Joseph County: 34.5 %St. Joseph County34.5Howard County: 33.6 %Howard County33.6Tippecanoe County: 30.8 %Tippecanoe County30.8Spencer County: 26.4 %Spencer County26.4Dubois County: 25.4 %Dubois County25.4Lake County: 15.9 %Lake County15.9Marion County: 11 %Marion County11
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2003 (%)Change on 2002
1Daviess County100+1.6 pts
2Perry County96.7+8.2 pts
3Putnam County96.6-1.8 pts
4Whitley County91.9+3.8 pts
5Gibson County84.2-4 pts
6Wabash County79.3+3.6 pts
7Hendricks County69.1+17.4 pts
8Knox County64.2+1.6 pts
9Porter County63.1+2.6 pts
10Carroll County62.8+15.5 pts
11Posey County59.6+10.5 pts
12Hamilton County54.1+1.1 pts
12Huntington County54.1-2.7 pts
12Jackson County54.1+7.1 pts
12Shelby County54.1+7.7 pts
16Hancock County53.6+1.7 pts
17Kosciusko County52.9n/a
18Johnson County51.9+4.9 pts
18Warrick County51.9+7.1 pts
20Morgan County51.4+8.2 pts
21Clark County51+15.4 pts
22Greene County50.8+6.5 pts
23Boone County50.3+5.5 pts
24Vigo County47.5+10.5 pts
25Delaware County47.2+3.9 pts
26Floyd County47.1+0.5 pts
27LaPorte County46.3+2.9 pts
28Elkhart County44.4+2.9 pts
29Washington County42.5+8.9 pts
30Madison County42.3+6.1 pts
31Vanderburgh County39.2-1.6 pts
32Allen County36.4+4.3 pts
33Henry County35+11.3 pts
34St. Joseph County34.5+2.2 pts
35Howard County33.6+9.2 pts
36Tippecanoe County30.8+4.2 pts
37Spencer County26.4+2.3 pts
38Dubois County25.4+5.2 pts
39Lake County15.9+3.8 pts
40Marion County11+3.1 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. 13 counties with data in other periods have no value for 2003 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), 2003) [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), 2003. 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?period=2003. 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), 2003. 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?period=2003.

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), 2003 [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?period=2003 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_indiana_by_2003,
  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), 2003}},
  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?period=2003. 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), 2003
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?period=2003
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/indiana-counties?period=2003.
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)?

Daviess County, with 100% in 2003, according to EPA.

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

Marion County, with 11% in 2003.

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. 13 counties have no value for 2003 and are not ranked.

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

Counties in Indiana: more rankings