Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in Michigan

Counties in Michigan by share of days with good air quality (US EPA AQI)

Calhoun County had the highest share of days with good air quality (US EPA AQI) of 31 counties in 2001, at 100%. Wayne County had the lowest, at 18.6%. The median was 62.3%. Source: EPA.

Keep it in a collection in your library.
Highest100Calhoun County
Lowest18.6Wayne County
Median62.331 counties

Map of counties, 2001

Allegan County: 38.7 %Alpena County: 61.3 %Bay County: 50.4 %Benzie County: 70.5 %Berrien County: 51 %Calhoun County: 100 %Cass County: 62.3 %Chippewa County: 68.1 %Clinton County: 68.3 %Genesee County: 52.7 %Grand Traverse County: 60.9 %Huron County: 68.6 %Ingham County: 63.7 %Kalamazoo County: 48.6 %Kent County: 34 %Keweenaw County: 86 %Lenawee County: 62.8 %Macomb County: 67.9 %Mason County: 69.9 %Missaukee County: 70.9 %Monroe County: 28.8 %Muskegon County: 57.2 %Oakland County: 68.1 %Ottawa County: 51.5 %Saginaw County: 50.8 %St. Clair County: 56 %Schoolcraft County: 78.2 %Tuscola County: 85.8 %Washtenaw County: 61.6 %Wayne County: 18.6 %Wexford County: 85.3 %
  • Under 50
  • 50 to 56
  • 56 to 62
  • 62 to 68
  • 68 to 71
  • 71 and over
  • No data
%, 2001. Hatched areas have no value for this period. Source: Invokely calculation with data from EPA. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2001

Calhoun County: 100 %Calhoun County100Keweenaw County: 86 %Keweenaw County86Tuscola County: 85.8 %Tuscola County85.8Wexford County: 85.3 %Wexford County85.3Schoolcraft County: 78.2 %Schoolcraft County78.2Missaukee County: 70.9 %Missaukee County70.9Benzie County: 70.5 %Benzie County70.5Mason County: 69.9 %Mason County69.9Huron County: 68.6 %Huron County68.6Clinton County: 68.3 %Clinton County68.3Chippewa County: 68.1 %Chippewa County68.1Oakland County: 68.1 %Oakland County68.1Macomb County: 67.9 %Macomb County67.9Ingham County: 63.7 %Ingham County63.7Lenawee County: 62.8 %Lenawee County62.8Cass County: 62.3 %Cass County62.3Washtenaw County: 61.6 %Washtenaw County61.6Alpena County: 61.3 %Alpena County61.3Grand Traverse County: 60.9 %Grand Traverse County60.9Muskegon County: 57.2 %Muskegon County57.2St. Clair County: 56 %St. Clair County56Genesee County: 52.7 %Genesee County52.7Ottawa County: 51.5 %Ottawa County51.5Berrien County: 51 %Berrien County51Saginaw County: 50.8 %Saginaw County50.8Bay County: 50.4 %Bay County50.4Kalamazoo County: 48.6 %Kalamazoo County48.6Allegan County: 38.7 %Allegan County38.7Kent County: 34 %Kent County34Monroe County: 28.8 %Monroe County28.8Wayne County: 18.6 %Wayne County18.6Calhoun County: 100 %Calhoun County100Keweenaw County: 86 %Keweenaw County86Tuscola County: 85.8 %Tuscola County85.8Wexford County: 85.3 %Wexford County85.3Schoolcraft County: 78.2 %Schoolcraft County78.2Missaukee County: 70.9 %Missaukee County70.9Benzie County: 70.5 %Benzie County70.5Mason County: 69.9 %Mason County69.9Huron County: 68.6 %Huron County68.6Clinton County: 68.3 %Clinton County68.3Chippewa County: 68.1 %Chippewa County68.1Oakland County: 68.1 %Oakland County68.1Macomb County: 67.9 %Macomb County67.9Ingham County: 63.7 %Ingham County63.7Lenawee County: 62.8 %Lenawee County62.8Cass County: 62.3 %Cass County62.3Washtenaw County: 61.6 %Washtenaw County61.6Alpena County: 61.3 %Alpena County61.3Grand Traverse County: 60.9 %Grand Traverse County60.9Muskegon County: 57.2 %Muskegon County57.2St. Clair County: 56 %St. Clair County56Genesee County: 52.7 %Genesee County52.7Ottawa County: 51.5 %Ottawa County51.5Berrien County: 51 %Berrien County51Saginaw County: 50.8 %Saginaw County50.8Bay County: 50.4 %Bay County50.4Kalamazoo County: 48.6 %Kalamazoo County48.6Allegan County: 38.7 %Allegan County38.7Kent County: 34 %Kent County34Monroe County: 28.8 %Monroe County28.8Wayne County: 18.6 %Wayne County18.6
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2001 (%)Change on 2000
1Calhoun County100+5 pts
2Keweenaw County86-7.3 pts
3Tuscola County85.8-3.9 pts
4Wexford County85.3-14.7 pts
5Schoolcraft County78.2-4.3 pts
6Missaukee County70.9-21.7 pts
7Benzie County70.5-9.8 pts
8Mason County69.9-9.3 pts
9Huron County68.6-10.5 pts
10Clinton County68.3-16.9 pts
11Chippewa County68.1n/a
11Oakland County68.1-8.3 pts
13Macomb County67.9-4.3 pts
14Ingham County63.7+4.1 pts
15Lenawee County62.8-13 pts
16Cass County62.3-5.6 pts
17Washtenaw County61.6-0.6 pts
18Alpena County61.3-4.1 pts
19Grand Traverse County60.9-3 pts
20Muskegon County57.2-6.6 pts
21St. Clair County56-6.8 pts
22Genesee County52.7-7.1 pts
23Ottawa County51.5-10.4 pts
24Berrien County51-4.1 pts
25Saginaw County50.8-6.2 pts
26Bay County50.4-3.4 pts
27Kalamazoo County48.6-8.4 pts
28Allegan County38.7-7.2 pts
29Kent County34-2.3 pts
30Monroe County28.8-0.3 pts
31Wayne County18.6-2.7 pts

Other periods

About this ranking

Days with a daily Air Quality Index of 0 to 50 (good) as a percentage of the days of the year with an AQI in a US county. Calculated by Invokely from the day counts in the EPA AirData annual summaries; both counts are stored with each value.

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: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts (Counties in Michigan by share of days with good air quality (US EPA AQI), 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: good days as a share of days with an AQI, calculated with stored counts, Counties in Michigan by share of days with good air quality (US EPA AQI), 2001. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/good-air-quality-days-share/michigan-counties?period=2001. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Counties in Michigan by share of days with good air quality (US EPA AQI), 2001. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/good-air-quality-days-share/michigan-counties?period=2001.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Counties in Michigan by share of days with good air quality (US EPA AQI), 2001 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/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: good days as a share of days with an AQI, calculated with stored counts: Counties in Michigan by share of days with good air quality (US EPA AQI), 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/good-air-quality-days-share/michigan-counties?period=2001. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts: Counties in Michigan by share of days with good air quality (US EPA AQI), 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/good-air-quality-days-share/michigan-counties?period=2001
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/michigan-counties?period=2001.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Questions

Which county has the highest share of days with good air quality (US EPA AQI)?

Calhoun County, with 100% in 2001, according to EPA.

Which county has the lowest share of days with good air quality (US EPA AQI)?

Wayne County, with 18.6% 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: good days as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 22 counties have no value for 2001 and are not ranked.

Share of days with good air quality (US EPA AQI): other rankings

Counties in Michigan: more rankings