Counties in Indiana by highest daily Air Quality Index (US EPA)

Marion County had the highest highest daily Air Quality Index (US EPA) of 39 counties in 2014, at 209. Hancock County had the lowest, at 67. The median was 108. Source: the U.S. Environmental Protection Agency.

Highest209Marion County

Lowest67Hancock County

Median10839 counties

Map of counties, 2014

Under 85
85 to 99
99 to 110
110 to 120
120 to 130
130 and over
No data

index, 2014. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2014

index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2014 index	Change on 2013
1	Marion County	209	+85
2	Monroe County	159	+81
3	Lake County	156	+42
4	Allen County	147	+50
5	Madison County	141	+23
6	Vigo County	134	+37
7	Delaware County	130	+42
8	Hamilton County	129	+45
8	St. Joseph County	129	-26
10	Tippecanoe County	128	+29
11	Elkhart County	126	0
11	LaPorte County	126	0
13	Whitley County	125	+21
14	Clark County	122	+29
15	Floyd County	119	+18
15	Henry County	119	+32
17	Porter County	115	-83
18	Bartholomew County	108	+15
18	Boone County	108	-4
18	Carroll County	108	+11
18	Vanderburgh County	108	0
18	Wabash County	108	+3
23	Warrick County	105	+8
24	Perry County	101	+1
25	Posey County	100	0
25	Shelby County	100	+3
27	Dubois County	97	+19
27	Morgan County	97	+4
29	Spencer County	96	+19
30	Jackson County	93	-12
31	Knox County	90	0
32	Greene County	88	-34
33	Howard County	84	n/a
34	Huntington County	80	+3
34	Montgomery County	80	n/a
36	Hendricks County	77	+3
37	Brown County	71	n/a
37	Johnson County	71	-22
39	Hancock County	67	-10

Other periods

About this ranking

Highest daily Air Quality Index (AQI) value recorded in a US county during the year, from the EPA AirData annual summaries. Values above 500 are beyond the AQI scale and are published as EPA computes them.

A single day decides the value, so one wildfire or dust event can set it. Dust from the dry Owens Lake bed puts Inyo and Mono counties in California in the thousands. 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 2014 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: highest daily AQI. 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: highest daily AQI (Counties in Indiana by highest daily Air Quality Index (US EPA), 2014) [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: highest daily AQI, Counties in Indiana by highest daily Air Quality Index (US EPA), 2014. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/indiana-counties?period=2014. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Counties in Indiana by highest daily Air Quality Index (US EPA), 2014. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/indiana-counties?period=2014.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Counties in Indiana by highest daily Air Quality Index (US EPA), 2014 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/highest-daily-air-quality-index/indiana-counties?period=2014 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_indiana_by_2014,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Counties in Indiana by highest daily Air Quality Index (US EPA), 2014}},
  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/highest-daily-air-quality-index/indiana-counties?period=2014. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest daily AQI. 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: highest daily AQI: Counties in Indiana by highest daily Air Quality Index (US EPA), 2014
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/highest-daily-air-quality-index/indiana-counties?period=2014
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/indiana-counties?period=2014.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest daily AQI. 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 highest daily Air Quality Index (US EPA)?

Marion County, with 209 in 2014, according to the U.S. Environmental Protection Agency.

Which county has the lowest highest daily Air Quality Index (US EPA)?

Hancock County, with 67 in 2014.

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: highest daily AQI. Retrieved 2026-10-12. 14 counties have no value for 2014 and are not ranked.