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

Iron County had the highest share of days with good air quality (US EPA AQI) of 31 counties in 2006, at 89.5%. Wayne County had the lowest, at 29.3%. The median was 70.3%. Source: EPA.

Highest89.5Iron County

Lowest29.3Wayne County

Median70.331 counties

Map of counties, 2006

Under 58
58 to 63
63 to 70
70 to 79
79 to 82
82 and over
No data

%, 2006. 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, 2006

%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2006 (%)	Change on 2005
1	Iron County	89.5	-2.5 pts
2	Keweenaw County	89	+3.3 pts
3	Wexford County	88.8	+4.3 pts
4	Tuscola County	88.7	+5.3 pts
5	Schoolcraft County	87.2	+2.8 pts
6	Huron County	82.3	+4.3 pts
7	Mason County	81	+9.6 pts
8	Clinton County	80.7	+16.2 pts
9	Benzie County	79.4	+10 pts
10	Leelanau County	79	+8 pts
11	Oakland County	78.6	+11.5 pts
12	Manistee County	77	n/a
13	Macomb County	76.2	+11.3 pts
14	Missaukee County	72.2	+8.3 pts
15	Cass County	71.4	+28.2 pts
16	Lenawee County	70.3	+13.2 pts
17	Washtenaw County	69	+8.6 pts
18	St. Clair County	68.1	+9 pts
19	Chippewa County	67	+1.4 pts
20	Berrien County	65.5	+22.8 pts
21	Muskegon County	62.8	+7.2 pts
22	Ottawa County	62.1	+13.6 pts
23	Kent County	61.1	+19.5 pts
24	Allegan County	59.4	+16.9 pts
25	Dickinson County	58.2	-21.8 pts
26	Genesee County	58	+4 pts
27	Ingham County	57.3	+9.4 pts
28	Kalamazoo County	55.2	+9.6 pts
29	Bay County	52.7	+4.8 pts
30	Monroe County	34.2	+2.9 pts
31	Wayne County	29.3	+6.8 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 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: 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), 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: 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), 2006. 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=2006. 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), 2006. 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=2006.

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), 2006 [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=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: 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), 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/good-air-quality-days-share/michigan-counties?period=2006. 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), 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/good-air-quality-days-share/michigan-counties?period=2006
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/michigan-counties?period=2006.
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  -

Embed this chart

Paste this code into a web page or a blog post. The chart shows the latest figures as they are published, with the source and a link back to this page.

Embed code

<iframe src="https://invokely.ai/embed/rankings/good-air-quality-days-share/michigan-counties?period=2006" width="760" height="500" title="Counties in Michigan by share of days with good air quality (US EPA AQI), 2006, chart from Invokely" loading="lazy" style="border:0;width:100%;max-width:760px" referrerpolicy="strict-origin-when-cross-origin"></iframe>

Sites that read oEmbed links, such as WordPress, can show the chart when you paste the link to this page.

Use this data in your AI agent

Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:

Rank Counties in Michigan by share of days with good air quality (US EPA AQI) using official data, and cite the source.

rank_places {"indicator":"aqi_good_days_share","level":"province","within":"Michigan","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=aqi_good_days_share&level=province&within=Michigan&limit=10

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

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

Iron County, with 89.5% in 2006, according to EPA.

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

Wayne County, with 29.3% 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: good days as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 22 counties have no value for 2006 and are not ranked.