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

Genesee County had the highest highest daily Air Quality Index (US EPA) of 32 counties in 1993, at 206. Gratiot County had the lowest, at 19. The median was 163. Source: the U.S. Environmental Protection Agency.

Highest206Genesee County

Lowest19Gratiot County

Median16332 counties

Map of counties, 1993

Under 59
59 to 140
140 to 160
160 to 180
180 to 200
200 and over
No data

index, 1993. 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, 1993

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

Full ranking

Rank	Counties	1993 index	Change on 1992
1	Genesee County	206	+55
2	Muskegon County	204	-3
3	Kent County	202	+36
4	Monroe County	201	+142
4	Tuscola County	201	+32
6	Allegan County	200	+110
6	Mason County	200	+136
8	Wayne County	197	+43
9	Macomb County	192	+33
10	Washtenaw County	190	-10
11	St. Clair County	177	-5
12	Delta County	172	-34
13	Oakland County	169	+8
14	Cass County	166	-21
15	Clinton County	164	-36
15	Kalamazoo County	164	-41
17	Benzie County	161	+11
18	Dickinson County	154	+3
18	Huron County	154	n/a
18	Ingham County	154	-36
21	Manistee County	151	+1
22	Berrien County	133	+28
23	Lenawee County	129	n/a
24	Bay County	93	-285
25	Marquette County	77	+28
26	Midland County	74	-12
27	Calhoun County	56	0
28	Saginaw County	51	-45
29	Van Buren County	48	-118
30	Cheboygan County	32	-61
31	Sanilac County	23	-22
32	Gratiot County	19	-17

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. 21 counties with data in other periods have no value for 1993 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 Michigan by highest daily Air Quality Index (US EPA), 1993) [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 Michigan by highest daily Air Quality Index (US EPA), 1993. 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/michigan-counties?period=1993. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Counties in Michigan by highest daily Air Quality Index (US EPA), 1993. 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/michigan-counties?period=1993.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Counties in Michigan by highest daily Air Quality Index (US EPA), 1993 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/highest-daily-air-quality-index/michigan-counties?period=1993 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_michigan_by_1993,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Counties in Michigan by highest daily Air Quality Index (US EPA), 1993}},
  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/michigan-counties?period=1993. 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 Michigan by highest daily Air Quality Index (US EPA), 1993
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/michigan-counties?period=1993
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/michigan-counties?period=1993.
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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Rank Counties in Michigan by highest daily Air Quality Index (US EPA) using official data, and cite the source.

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Questions

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

Genesee County, with 206 in 1993, according to the U.S. Environmental Protection Agency.

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

Gratiot County, with 19 in 1993.

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. 21 counties have no value for 1993 and are not ranked.