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

Adams County had the highest share of days with good air quality (US EPA AQI) of 48 counties in 1994, at 100%. Cuyahoga County had the lowest, at 47.1%. The median was 71.7%. Source: EPA.

Highest100Adams County

Lowest47.1Cuyahoga County

Median71.748 counties

Map of counties, 1994

Under 58
58 to 68
68 to 72
72 to 80
80 to 95
95 and over
No data

%, 1994. 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, 1994

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

Full ranking

Rank	Counties	1994 (%)	Change on 1993
1	Adams County	100	+1.7 pts
1	Hancock County	100	0 pts
1	Jackson County	100	+1.7 pts
1	Ottawa County	100	+1.7 pts
1	Pickaway County	100	+0.3 pts
6	Greene County	96.7	+3.4 pts
7	Athens County	96.4	-3.6 pts
8	Richland County	95.7	+1.2 pts
9	Wyandot County	94.3	+0.9 pts
10	Scioto County	91.6	-0.1 pts
11	Seneca County	90.7	-2.8 pts
12	Monroe County	88.3	+7.8 pts
13	Sandusky County	87.4	+5.9 pts
14	Belmont County	87.1	-4.7 pts
15	Miami County	85.4	+18.9 pts
16	Mahoning County	83	+1.4 pts
17	Summit County	78.6	+2.2 pts
18	Lucas County	76.7	-6.9 pts
19	Lorain County	75.3	-5.6 pts
19	Stark County	75.3	+5.2 pts
21	Lake County	74.8	-2.2 pts
22	Franklin County	73.7	-2.7 pts
23	Crawford County	73	-4.6 pts
24	Ashtabula County	71.7	-7 pts
24	Fayette County	71.7	+0.2 pts
26	Tuscarawas County	71.6	-9 pts
27	Columbiana County	70.4	+4.4 pts
27	Montgomery County	70.4	-6.9 pts
29	Noble County	70.3	-25.3 pts
30	Trumbull County	69.2	+3.6 pts
31	Hamilton County	69	+2.4 pts
32	Butler County	67.9	-3.1 pts
33	Jefferson County	67.7	-3 pts
34	Lawrence County	67.1	-4.5 pts
35	Preble County	66.8	-2.4 pts
36	Portage County	64.8	-0.1 pts
37	Knox County	60	-2.7 pts
38	Medina County	59.2	-0.1 pts
39	Allen County	58.8	-6.2 pts
40	Clermont County	58.6	+0.9 pts
41	Madison County	55.9	+5.6 pts
42	Licking County	55.8	-13.4 pts
43	Clinton County	54.7	+4.9 pts
44	Warren County	54.1	-0.4 pts
45	Clark County	52.3	-12.2 pts
46	Washington County	52.1	-2.5 pts
47	Logan County	49.8	-14.8 pts
48	Cuyahoga County	47.1	-5 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. 10 counties with data in other periods have no value for 1994 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 Ohio by share of days with good air quality (US EPA AQI), 1994) [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 Ohio by share of days with good air quality (US EPA AQI), 1994. 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/ohio-counties?period=1994. 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 Ohio by share of days with good air quality (US EPA AQI), 1994. 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/ohio-counties?period=1994.

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 Ohio by share of days with good air quality (US EPA AQI), 1994 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/ohio-counties?period=1994 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_ohio_by_1994,
  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 Ohio by share of days with good air quality (US EPA AQI), 1994}},
  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/ohio-counties?period=1994. 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 Ohio by share of days with good air quality (US EPA AQI), 1994
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/ohio-counties?period=1994
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/ohio-counties?period=1994.
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/ohio-counties?period=1994" width="760" height="500" title="Counties in Ohio by share of days with good air quality (US EPA AQI), 1994, 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 Ohio 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":"Ohio","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=aqi_good_days_share&level=province&within=Ohio&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)?

Adams County, with 100% in 1994, according to EPA.

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

Cuyahoga County, with 47.1% in 1994.

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. 10 counties have no value for 1994 and are not ranked.