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

Allegan County had the highest highest daily Air Quality Index (US EPA) of 31 counties in 2005, at 208. Iron County had the lowest, at 60. The median was 164. Source: the U.S. Environmental Protection Agency.

Highest208Allegan County

Lowest60Iron County

Median16431 counties

Map of counties, 2005

Under 130
130 to 150
150 to 160
160 to 180
180 to 190
190 and over
No data

index, 2005. 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, 2005

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

Full ranking

Rank	Counties	2005 index	Change on 2004
1	Allegan County	208	+6
1	Muskegon County	208	+79
3	St. Clair County	202	+73
4	Washtenaw County	200	+53
5	Macomb County	195	+52
6	Mason County	187	+51
7	Ottawa County	182	+56
7	Schoolcraft County	182	+46
9	Lenawee County	179	+29
10	Benzie County	177	+41
10	Berrien County	177	+51
12	Ingham County	174	+52
13	Kent County	172	+32
13	Leelanau County	172	+36
15	Wayne County	169	+18
16	Cass County	164	+21
17	Monroe County	163	+54
18	Kalamazoo County	156	+51
18	Tuscola County	156	+2
20	Huron County	151	-5
20	Missaukee County	151	+4
20	Oakland County	151	+22
23	Genesee County	150	-1
24	Clinton County	143	+14
25	Wexford County	129	-18
26	Chippewa County	126	+32
27	Saginaw County	125	+31
28	Bay County	124	+27
29	Keweenaw County	73	-1
30	Dickinson County	68	n/a
31	Iron County	60	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. 22 counties with data in other periods have no value for 2005 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), 2005) [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), 2005. 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=2005. 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), 2005. 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=2005.

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), 2005 [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=2005 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_michigan_by_2005,
  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), 2005}},
  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=2005. 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), 2005
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=2005
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/michigan-counties?period=2005.
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.

rank_places {"indicator":"aqi_max","level":"province","within":"Michigan","limit":10}
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Questions

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

Allegan County, with 208 in 2005, according to the U.S. Environmental Protection Agency.

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

Iron County, with 60 in 2005.

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. 22 counties have no value for 2005 and are not ranked.