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

Hamilton County had the highest highest daily Air Quality Index (US EPA) of 43 counties in 2001, at 195. Whitley County had the lowest, at 37. The median was 154. Source: the U.S. Environmental Protection Agency.

Highest195Hamilton County

Lowest37Whitley County

Median15443 counties

Map of counties, 2001

Under 89
89 to 130
130 to 150
150 to 170
170 to 180
180 and over
No data

index, 2001. 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, 2001

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

Full ranking

Rank	Counties	2001 index	Change on 2000
1	Hamilton County	195	+8
2	Hancock County	192	+10
2	Madison County	192	+28
4	LaPorte County	182	-13
4	Marion County	182	0
4	Perry County	182	+10
4	Shelby County	182	+3
8	Lake County	179	+15
9	Boone County	177	+11
9	Clark County	177	+21
9	Wabash County	177	+3
12	Delaware County	174	+40
12	Porter County	174	-16
14	St. Joseph County	172	+6
15	Allen County	169	-13
16	Greene County	166	-8
17	Warrick County	164	+28
18	Vigo County	161	+7
19	Hendricks County	159	-45
19	Morgan County	159	-10
21	Carroll County	154	n/a
21	Jackson County	154	-10
21	Knox County	154	0
24	Floyd County	152	+19
25	Johnson County	151	-13
26	Huntington County	150	-19
27	Vanderburgh County	135	-15
28	Posey County	133	-36
29	Elkhart County	131	+5
30	Tippecanoe County	130	+19
31	Washington County	122	n/a
32	Henry County	118	+47
33	Dubois County	114	-19
34	Howard County	113	+12
35	Gibson County	112	0
36	Spencer County	89	-31
37	DeKalb County	70	+15
38	Bartholomew County	61	+3
39	Putnam County	57	+2
40	Daviess County	44	-12
41	Wayne County	43	-7
42	Jasper County	38	-2
43	Whitley County	37	n/a

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. 10 counties with data in other periods have no value for 2001 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), 2001) [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), 2001. 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=2001. 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), 2001. 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=2001.

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), 2001 [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=2001 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_indiana_by_2001,
  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), 2001}},
  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=2001. 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), 2001
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=2001
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/indiana-counties?period=2001.
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  -

Embed this chart

Paste this code into a web page or a blog post. The chart shows the latest figures as they are published, with the source and a link back to this page.

Embed code

<iframe src="https://invokely.ai/embed/rankings/highest-daily-air-quality-index/indiana-counties?period=2001" width="760" height="500" title="Counties in Indiana by highest daily Air Quality Index (US EPA), 2001, chart from Invokely" loading="lazy" style="border:0;width:100%;max-width:760px" referrerpolicy="strict-origin-when-cross-origin"></iframe>

Sites that read oEmbed links, such as WordPress, can show the chart when you paste the link to this page.

Use this data in your AI agent

Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:

Rank Counties in Indiana by highest daily Air Quality Index (US EPA) using official data, and cite the source.

rank_places {"indicator":"aqi_max","level":"province","within":"Indiana","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=aqi_max&level=province&within=Indiana&limit=10

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

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

Hamilton County, with 195 in 2001, according to the U.S. Environmental Protection Agency.

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

Whitley County, with 37 in 2001.

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. 10 counties have no value for 2001 and are not ranked.