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 2005, at 63. Keweenaw County had the lowest, at 15. The median was 44. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest63Wayne County
Lowest15Keweenaw County
Median4431 counties

Map of counties, 2005

Allegan County: 54 indexBay County: 52 indexBenzie County: 43 indexBerrien County: 54 indexCass County: 58 indexChippewa County: 39 indexClinton County: 44 indexDickinson County: 38 indexGenesee County: 48 indexHuron County: 41 indexIngham County: 52 indexIron County: 19 indexKalamazoo County: 54 indexKent County: 55 indexKeweenaw County: 15 indexLeelanau County: 43 indexLenawee County: 47 indexMacomb County: 40 indexMason County: 41 indexMissaukee County: 43 indexMonroe County: 58 indexMuskegon County: 48 indexOakland County: 38 indexOttawa County: 51 indexSaginaw County: 50 indexSt. Clair County: 45 indexSchoolcraft County: 34 indexTuscola County: 35 indexWashtenaw County: 44 indexWayne County: 63 indexWexford County: 37 index
  • Under 38
  • 38 to 41
  • 41 to 44
  • 44 to 50
  • 50 to 54
  • 54 and over
  • No data
index, 2005. 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, 2005

Wayne County: 63 indexWayne County63Cass County: 58 indexCass County58Monroe County: 58 indexMonroe County58Kent County: 55 indexKent County55Allegan County: 54 indexAllegan County54Berrien County: 54 indexBerrien County54Kalamazoo County: 54 indexKalamazoo County54Bay County: 52 indexBay County52Ingham County: 52 indexIngham County52Ottawa County: 51 indexOttawa County51Saginaw County: 50 indexSaginaw County50Genesee County: 48 indexGenesee County48Muskegon County: 48 indexMuskegon County48Lenawee County: 47 indexLenawee County47St. Clair County: 45 indexSt. Clair County45Clinton County: 44 indexClinton County44Washtenaw County: 44 indexWashtenaw County44Benzie County: 43 indexBenzie County43Leelanau County: 43 indexLeelanau County43Missaukee County: 43 indexMissaukee County43Huron County: 41 indexHuron County41Mason County: 41 indexMason County41Macomb County: 40 indexMacomb County40Chippewa County: 39 indexChippewa County39Dickinson County: 38 indexDickinson County38Oakland County: 38 indexOakland County38Wexford County: 37 indexWexford County37Tuscola County: 35 indexTuscola County35Schoolcraft County: 34 indexSchoolcraft County34Iron County: 19 indexIron County19Keweenaw County: 15 indexKeweenaw County15Wayne County: 63 indexWayne County63Cass County: 58 indexCass County58Monroe County: 58 indexMonroe County58Kent County: 55 indexKent County55Allegan County: 54 indexAllegan County54Berrien County: 54 indexBerrien County54Kalamazoo County: 54 indexKalamazoo County54Bay County: 52 indexBay County52Ingham County: 52 indexIngham County52Ottawa County: 51 indexOttawa County51Saginaw County: 50 indexSaginaw County50Genesee County: 48 indexGenesee County48Muskegon County: 48 indexMuskegon County48Lenawee County: 47 indexLenawee County47St. Clair County: 45 indexSt. Clair County45Clinton County: 44 indexClinton County44Washtenaw County: 44 indexWashtenaw County44Benzie County: 43 indexBenzie County43Leelanau County: 43 indexLeelanau County43Missaukee County: 43 indexMissaukee County43Huron County: 41 indexHuron County41Mason County: 41 indexMason County41Macomb County: 40 indexMacomb County40Chippewa County: 39 indexChippewa County39Dickinson County: 38 indexDickinson County38Oakland County: 38 indexOakland County38Wexford County: 37 indexWexford County37Tuscola County: 35 indexTuscola County35Schoolcraft County: 34 indexSchoolcraft County34Iron County: 19 indexIron County19Keweenaw County: 15 indexKeweenaw County15
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2005
index		Change on 2004
1Wayne County63+1
2Cass County58+14
2Monroe County58+4
4Kent County55+3
5Allegan County54+3
5Berrien County54+10
5Kalamazoo County54+9
8Bay County52+11
8Ingham County52+11
10Ottawa County51+9
11Saginaw County50+12
12Genesee County48+13
12Muskegon County48+10
14Lenawee County47+4
15St. Clair County45+7
16Clinton County44+4
16Washtenaw County44+5
18Benzie County43+4
18Leelanau County43+5
18Missaukee County43+4
21Huron County41+4
21Mason County41+3
23Macomb County40+6
24Chippewa County39+6
25Dickinson County38n/a
25Oakland County38+3
27Wexford County37+3
28Tuscola County35+2
29Schoolcraft County34-2
30Iron County19n/a
31Keweenaw County15+1

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 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: 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), 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: median daily AQI, Counties in Michigan by median 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/median-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: median daily AQI. Counties in Michigan by median 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/median-air-quality-index/michigan-counties?period=2005.

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), 2005 [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=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: median daily AQI: Counties in Michigan by median 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/median-air-quality-index/michigan-counties?period=2005. 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), 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/median-air-quality-index/michigan-counties?period=2005
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-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: 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.
rank_places {"indicator":"aqi_median","level":"province","within":"Michigan","limit":10}
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Questions

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

Wayne County, with 63 in 2005, according to the U.S. Environmental Protection Agency.

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

Keweenaw County, with 15 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: median daily AQI. Retrieved 2026-10-12. 22 counties have no value for 2005 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Michigan: more rankings