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 2006, at 59. Keweenaw County had the lowest, at 16. The median was 41. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest59Wayne County
Lowest16Keweenaw County
Median4131 counties

Map of counties, 2006

Allegan County: 46 indexBay County: 43 indexBenzie County: 40 indexBerrien County: 46 indexCass County: 45 indexChippewa County: 37 indexClinton County: 41 indexDickinson County: 44 indexGenesee County: 46 indexHuron County: 40 indexIngham County: 47 indexIron County: 23 indexKalamazoo County: 48 indexKent County: 44 indexKeweenaw County: 16 indexLeelanau County: 40 indexLenawee County: 44 indexMacomb County: 34 indexManistee County: 34 indexMason County: 39 indexMissaukee County: 42 indexMonroe County: 56 indexMuskegon County: 44 indexOakland County: 30 indexOttawa County: 44 indexSt. Clair County: 40 indexSchoolcraft County: 36 indexTuscola County: 34 indexWashtenaw County: 40 indexWayne County: 59 indexWexford County: 35 index
  • Under 34
  • 34 to 40
  • 40 to 41
  • 41 to 44
  • 44 to 46
  • 46 and over
  • No data
index, 2006. 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, 2006

Wayne County: 59 indexWayne County59Monroe County: 56 indexMonroe County56Kalamazoo County: 48 indexKalamazoo County48Ingham County: 47 indexIngham County47Allegan County: 46 indexAllegan County46Berrien County: 46 indexBerrien County46Genesee County: 46 indexGenesee County46Cass County: 45 indexCass County45Dickinson County: 44 indexDickinson County44Kent County: 44 indexKent County44Lenawee County: 44 indexLenawee County44Muskegon County: 44 indexMuskegon County44Ottawa County: 44 indexOttawa County44Bay County: 43 indexBay County43Missaukee County: 42 indexMissaukee County42Clinton County: 41 indexClinton County41Benzie County: 40 indexBenzie County40Huron County: 40 indexHuron County40Leelanau County: 40 indexLeelanau County40St. Clair County: 40 indexSt. Clair County40Washtenaw County: 40 indexWashtenaw County40Mason County: 39 indexMason County39Chippewa County: 37 indexChippewa County37Schoolcraft County: 36 indexSchoolcraft County36Wexford County: 35 indexWexford County35Macomb County: 34 indexMacomb County34Manistee County: 34 indexManistee County34Tuscola County: 34 indexTuscola County34Oakland County: 30 indexOakland County30Iron County: 23 indexIron County23Keweenaw County: 16 indexKeweenaw County16Wayne County: 59 indexWayne County59Monroe County: 56 indexMonroe County56Kalamazoo County: 48 indexKalamazoo County48Ingham County: 47 indexIngham County47Allegan County: 46 indexAllegan County46Berrien County: 46 indexBerrien County46Genesee County: 46 indexGenesee County46Cass County: 45 indexCass County45Dickinson County: 44 indexDickinson County44Kent County: 44 indexKent County44Lenawee County: 44 indexLenawee County44Muskegon County: 44 indexMuskegon County44Ottawa County: 44 indexOttawa County44Bay County: 43 indexBay County43Missaukee County: 42 indexMissaukee County42Clinton County: 41 indexClinton County41Benzie County: 40 indexBenzie County40Huron County: 40 indexHuron County40Leelanau County: 40 indexLeelanau County40St. Clair County: 40 indexSt. Clair County40Washtenaw County: 40 indexWashtenaw County40Mason County: 39 indexMason County39Chippewa County: 37 indexChippewa County37Schoolcraft County: 36 indexSchoolcraft County36Wexford County: 35 indexWexford County35Macomb County: 34 indexMacomb County34Manistee County: 34 indexManistee County34Tuscola County: 34 indexTuscola County34Oakland County: 30 indexOakland County30Iron County: 23 indexIron County23Keweenaw County: 16 indexKeweenaw County16
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2006
index		Change on 2005
1Wayne County59-4
2Monroe County56-2
3Kalamazoo County48-6
4Ingham County47-5
5Allegan County46-8
5Berrien County46-8
5Genesee County46-2
8Cass County45-13
9Dickinson County44+6
9Kent County44-11
9Lenawee County44-3
9Muskegon County44-4
9Ottawa County44-7
14Bay County43-9
15Missaukee County42-1
16Clinton County41-3
17Benzie County40-3
17Huron County40-1
17Leelanau County40-3
17St. Clair County40-5
17Washtenaw County40-4
22Mason County39-2
23Chippewa County37-2
24Schoolcraft County36+2
25Wexford County35-2
26Macomb County34-6
26Manistee County34n/a
26Tuscola County34-1
29Oakland County30-8
30Iron County23+4
31Keweenaw County16+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 2006 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), 2006) [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), 2006. 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=2006. 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), 2006. 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=2006.

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), 2006 [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=2006 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_michigan_by_2006,
  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), 2006}},
  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=2006. 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), 2006
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=2006
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/michigan-counties?period=2006.
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 59 in 2006, according to the U.S. Environmental Protection Agency.

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

Keweenaw County, with 16 in 2006.

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 2006 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Michigan: more rankings