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

Marion County had the highest highest daily Air Quality Index (US EPA) of 42 counties in 2002, at 227. Wayne County had the lowest, at 44. The median was 189. Source: the U.S. Environmental Protection Agency.

Highest227Marion County

Lowest44Wayne County

Median18942 counties

Map of counties, 2002

Under 88
88 to 160
160 to 190
190 to 200
200 to 210
210 and over
No data

index, 2002. 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, 2002

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

Full ranking

Rank	Counties	2002 index	Change on 2001
1	Marion County	227	+45
2	St. Joseph County	216	+44
3	Porter County	215	+41
4	Shelby County	213	+31
5	LaPorte County	212	+30
6	Boone County	210	+33
7	Hendricks County	209	+50
8	Warrick County	208	+44
9	Floyd County	207	+55
10	Elkhart County	206	+75
10	Johnson County	206	+55
10	Lake County	206	+27
13	Madison County	204	+12
14	Hamilton County	203	+8
15	Hancock County	202	+10
16	Posey County	201	+68
17	Vanderburgh County	200	+65
18	Carroll County	197	+43
18	Vigo County	197	+36
20	Clark County	195	+18
21	Morgan County	190	+31
22	Allen County	187	+18
23	Delaware County	182	+8
24	Greene County	179	+13
25	Wabash County	177	0
26	Knox County	174	+20
27	Jackson County	172	+18
28	Huntington County	161	+11
29	Gibson County	143	+31
30	Dubois County	126	+12
31	Henry County	124	+6
32	Tippecanoe County	120	-10
33	Howard County	111	-2
34	Washington County	96	-26
35	Perry County	88	-94
36	Spencer County	87	-2
37	DeKalb County	78	+8
37	Whitley County	78	+41
39	Putnam County	58	+1
40	Daviess County	51	+7
41	Jasper County	47	+9
42	Wayne County	44	+1

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. 11 counties with data in other periods have no value for 2002 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), 2002) [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), 2002. 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=2002. 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), 2002. 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=2002.

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), 2002 [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=2002 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_indiana_by_2002,
  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), 2002}},
  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=2002. 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), 2002
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=2002
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/indiana-counties?period=2002.
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 227 in 2002, according to the U.S. Environmental Protection Agency.

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

Wayne County, with 44 in 2002.

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. 11 counties have no value for 2002 and are not ranked.