Data / Rankings / Median Air Quality Index (US EPA) / Counties in Michigan

Counties in Michigan by median Air Quality Index (US EPA)

Wayne County had the highest median Air Quality Index (US EPA) of 31 counties in 2001, at 68. Calhoun County had the lowest, at 18. The median was 44. Source: the U.S. Environmental Protection Agency.

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Highest68Wayne County
Lowest18Calhoun County
Median4431 counties

Map of counties, 2001

Allegan County: 55 indexAlpena County: 36 indexBay County: 50 indexBenzie County: 44 indexBerrien County: 49 indexCalhoun County: 18 indexCass County: 44 indexChippewa County: 38 indexClinton County: 43 indexGenesee County: 49 indexGrand Traverse County: 40 indexHuron County: 44 indexIngham County: 42 indexKalamazoo County: 53 indexKent County: 58 indexKeweenaw County: 21 indexLenawee County: 46 indexMacomb County: 40 indexMason County: 42 indexMissaukee County: 43 indexMonroe County: 58 indexMuskegon County: 47 indexOakland County: 34 indexOttawa County: 49 indexSaginaw County: 50 indexSt. Clair County: 46 indexSchoolcraft County: 22 indexTuscola County: 33 indexWashtenaw County: 43 indexWayne County: 68 indexWexford County: 35 index
  • Under 35
  • 35 to 42
  • 42 to 44
  • 44 to 47
  • 47 to 50
  • 50 and over
  • No data
index, 2001. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2001

Wayne County: 68 indexWayne County68Kent County: 58 indexKent County58Monroe County: 58 indexMonroe County58Allegan County: 55 indexAllegan County55Kalamazoo County: 53 indexKalamazoo County53Bay County: 50 indexBay County50Saginaw County: 50 indexSaginaw County50Berrien County: 49 indexBerrien County49Genesee County: 49 indexGenesee County49Ottawa County: 49 indexOttawa County49Muskegon County: 47 indexMuskegon County47Lenawee County: 46 indexLenawee County46St. Clair County: 46 indexSt. Clair County46Benzie County: 44 indexBenzie County44Cass County: 44 indexCass County44Huron County: 44 indexHuron County44Clinton County: 43 indexClinton County43Missaukee County: 43 indexMissaukee County43Washtenaw County: 43 indexWashtenaw County43Ingham County: 42 indexIngham County42Mason County: 42 indexMason County42Grand Traverse County: 40 indexGrand Traverse County40Macomb County: 40 indexMacomb County40Chippewa County: 38 indexChippewa County38Alpena County: 36 indexAlpena County36Wexford County: 35 indexWexford County35Oakland County: 34 indexOakland County34Tuscola County: 33 indexTuscola County33Schoolcraft County: 22 indexSchoolcraft County22Keweenaw County: 21 indexKeweenaw County21Calhoun County: 18 indexCalhoun County18Wayne County: 68 indexWayne County68Kent County: 58 indexKent County58Monroe County: 58 indexMonroe County58Allegan County: 55 indexAllegan County55Kalamazoo County: 53 indexKalamazoo County53Bay County: 50 indexBay County50Saginaw County: 50 indexSaginaw County50Berrien County: 49 indexBerrien County49Genesee County: 49 indexGenesee County49Ottawa County: 49 indexOttawa County49Muskegon County: 47 indexMuskegon County47Lenawee County: 46 indexLenawee County46St. Clair County: 46 indexSt. Clair County46Benzie County: 44 indexBenzie County44Cass County: 44 indexCass County44Huron County: 44 indexHuron County44Clinton County: 43 indexClinton County43Missaukee County: 43 indexMissaukee County43Washtenaw County: 43 indexWashtenaw County43Ingham County: 42 indexIngham County42Mason County: 42 indexMason County42Grand Traverse County: 40 indexGrand Traverse County40Macomb County: 40 indexMacomb County40Chippewa County: 38 indexChippewa County38Alpena County: 36 indexAlpena County36Wexford County: 35 indexWexford County35Oakland County: 34 indexOakland County34Tuscola County: 33 indexTuscola County33Schoolcraft County: 22 indexSchoolcraft County22Keweenaw County: 21 indexKeweenaw County21Calhoun County: 18 indexCalhoun County18
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2001
index		Change on 2000
1Wayne County68+2
2Kent County58+1
2Monroe County58-2
4Allegan County55+2
5Kalamazoo County53+6
6Bay County50+4
6Saginaw County50+5
8Berrien County49+1
8Genesee County49+5
8Ottawa County49+5
11Muskegon County47+4
12Lenawee County46+2
12St. Clair County46+5
14Benzie County44+4
14Cass County440
14Huron County44+6
17Clinton County43+4
17Missaukee County43+22
17Washtenaw County430
20Ingham County42-5
20Mason County42+2
22Grand Traverse County40+1
22Macomb County40+7
24Chippewa County38n/a
25Alpena County360
26Wexford County35+6
27Oakland County34+4
28Tuscola County330
29Schoolcraft County22+5
30Keweenaw County21+3
31Calhoun County18-5

Other periods

About this ranking

Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries.

More on how it is measured
  • The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide).
  • Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.

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 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: median 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: median daily AQI (Counties in Michigan by median 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: median daily AQI, Counties in Michigan by median 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/median-air-quality-index/michigan-counties?period=2001. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Michigan by median 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/median-air-quality-index/michigan-counties?period=2001.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Michigan by median 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/median-air-quality-index/michigan-counties?period=2001 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_michigan_by_2001,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Michigan by median 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/median-air-quality-index/michigan-counties?period=2001. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median 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: median daily AQI: Counties in Michigan by median 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/median-air-quality-index/michigan-counties?period=2001
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/michigan-counties?period=2001.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median 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 median Air Quality Index (US EPA) using official data, and cite the source.
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Questions

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

Wayne County, with 68 in 2001, according to the U.S. Environmental Protection Agency.

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

Calhoun County, with 18 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: median daily AQI. Retrieved 2026-10-12. 22 counties have no value for 2001 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Michigan: more rankings