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)

Gratiot County had the highest share of days with good air quality (US EPA AQI) of 31 counties in 1992, at 100%. Cass County had the lowest, at 63.6%. The median was 86.7%. Source: EPA.

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Highest100Gratiot County
Lowest63.6Cass County
Median86.731 counties

Map of counties, 1992

Allegan County: 91 %Bay County: 84.8 %Benzie County: 84.1 %Berrien County: 83.9 %Calhoun County: 96.7 %Cass County: 63.6 %Cheboygan County: 97.3 %Clinton County: 77.5 %Delta County: 71.3 %Dickinson County: 92.3 %Genesee County: 84.5 %Gratiot County: 100 %Ingham County: 82.5 %Kalamazoo County: 83.9 %Kent County: 84.2 %Macomb County: 89.3 %Manistee County: 86.7 %Marquette County: 100 %Mason County: 91.3 %Midland County: 99.2 %Monroe County: 98.3 %Muskegon County: 72.5 %Oakland County: 92.9 %Ottawa County: 71.6 %Saginaw County: 91.5 %St. Clair County: 80.9 %Sanilac County: 100 %Tuscola County: 87.6 %Van Buren County: 94.5 %Washtenaw County: 83.5 %Wayne County: 74.6 %
  • Under 78
  • 78 to 84
  • 84 to 87
  • 87 to 92
  • 92 to 97
  • 97 and over
  • No data
%, 1992. 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, 1992

Gratiot County: 100 %Gratiot County100Marquette County: 100 %Marquette County100Sanilac County: 100 %Sanilac County100Midland County: 99.2 %Midland County99.2Monroe County: 98.3 %Monroe County98.3Cheboygan County: 97.3 %Cheboygan County97.3Calhoun County: 96.7 %Calhoun County96.7Van Buren County: 94.5 %Van Buren County94.5Oakland County: 92.9 %Oakland County92.9Dickinson County: 92.3 %Dickinson County92.3Saginaw County: 91.5 %Saginaw County91.5Mason County: 91.3 %Mason County91.3Allegan County: 91 %Allegan County91Macomb County: 89.3 %Macomb County89.3Tuscola County: 87.6 %Tuscola County87.6Manistee County: 86.7 %Manistee County86.7Bay County: 84.8 %Bay County84.8Genesee County: 84.5 %Genesee County84.5Kent County: 84.2 %Kent County84.2Benzie County: 84.1 %Benzie County84.1Berrien County: 83.9 %Berrien County83.9Kalamazoo County: 83.9 %Kalamazoo County83.9Washtenaw County: 83.5 %Washtenaw County83.5Ingham County: 82.5 %Ingham County82.5St. Clair County: 80.9 %St. Clair County80.9Clinton County: 77.5 %Clinton County77.5Wayne County: 74.6 %Wayne County74.6Muskegon County: 72.5 %Muskegon County72.5Ottawa County: 71.6 %Ottawa County71.6Delta County: 71.3 %Delta County71.3Cass County: 63.6 %Cass County63.6Gratiot County: 100 %Gratiot County100Marquette County: 100 %Marquette County100Sanilac County: 100 %Sanilac County100Midland County: 99.2 %Midland County99.2Monroe County: 98.3 %Monroe County98.3Cheboygan County: 97.3 %Cheboygan County97.3Calhoun County: 96.7 %Calhoun County96.7Van Buren County: 94.5 %Van Buren County94.5Oakland County: 92.9 %Oakland County92.9Dickinson County: 92.3 %Dickinson County92.3Saginaw County: 91.5 %Saginaw County91.5Mason County: 91.3 %Mason County91.3Allegan County: 91 %Allegan County91Macomb County: 89.3 %Macomb County89.3Tuscola County: 87.6 %Tuscola County87.6Manistee County: 86.7 %Manistee County86.7Bay County: 84.8 %Bay County84.8Genesee County: 84.5 %Genesee County84.5Kent County: 84.2 %Kent County84.2Benzie County: 84.1 %Benzie County84.1Berrien County: 83.9 %Berrien County83.9Kalamazoo County: 83.9 %Kalamazoo County83.9Washtenaw County: 83.5 %Washtenaw County83.5Ingham County: 82.5 %Ingham County82.5St. Clair County: 80.9 %St. Clair County80.9Clinton County: 77.5 %Clinton County77.5Wayne County: 74.6 %Wayne County74.6Muskegon County: 72.5 %Muskegon County72.5Ottawa County: 71.6 %Ottawa County71.6Delta County: 71.3 %Delta County71.3Cass County: 63.6 %Cass County63.6
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties1992 (%)Change on 1991
1Gratiot County1000 pts
1Marquette County100+3.3 pts
1Sanilac County100n/a
4Midland County99.2+0.8 pts
5Monroe County98.3+0.2 pts
6Cheboygan County97.3n/a
7Calhoun County96.7+8.4 pts
8Van Buren County94.5+9.6 pts
9Oakland County92.9+12.4 pts
10Dickinson County92.3-0.8 pts
11Saginaw County91.5+0.7 pts
12Mason County91.3+29.1 pts
13Allegan County91+54.4 pts
14Macomb County89.3+12.3 pts
15Tuscola County87.6+7.9 pts
16Manistee County86.7+4.9 pts
17Bay County84.8-1.9 pts
18Genesee County84.5+14 pts
19Kent County84.2+4.7 pts
20Benzie County84.1+23.5 pts
21Berrien County83.9+48.5 pts
21Kalamazoo County83.9-7.6 pts
23Washtenaw County83.5+7.7 pts
24Ingham County82.5+12.4 pts
25St. Clair County80.9+15.5 pts
26Clinton County77.5+10.4 pts
27Wayne County74.6+9.4 pts
28Muskegon County72.5+8.7 pts
29Ottawa County71.6+13.2 pts
30Delta County71.3+4 pts
31Cass County63.6+25.1 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 1992 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), 1992) [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), 1992. 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=1992. 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), 1992. 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=1992.

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), 1992 [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=1992 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_michigan_by_1992,
  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), 1992}},
  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=1992. 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), 1992
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=1992
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/michigan-counties?period=1992.
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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Rank Counties in Michigan by share of days with good air quality (US EPA AQI) using official data, and cite the source.
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Questions

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

Gratiot County, with 100% in 1992, according to EPA.

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

Cass County, with 63.6% in 1992.

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 1992 and are not ranked.

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

Counties in Michigan: more rankings