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

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

Athens County had the highest share of days with good air quality (US EPA AQI) of 45 counties in 1995, at 100%. Clinton County had the lowest, at 47.3%. The median was 66.3%. Source: EPA.

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Highest100Athens County
Lowest47.3Clinton County
Median66.345 counties

Map of counties, 1995

Adams County: 98.7 %Allen County: 65.1 %Ashtabula County: 63.6 %Athens County: 100 %Belmont County: 90.5 %Butler County: 66.3 %Clark County: 48.1 %Clermont County: 55.4 %Clinton County: 47.3 %Columbiana County: 82.3 %Crawford County: 70.7 %Cuyahoga County: 55.1 %Fayette County: 62.8 %Franklin County: 75.9 %Greene County: 98.3 %Hamilton County: 64.1 %Hancock County: 100 %Jefferson County: 63 %Knox County: 63.1 %Lake County: 74.8 %Lawrence County: 61.9 %Licking County: 51.9 %Logan County: 54.1 %Lorain County: 75.9 %Lucas County: 77 %Madison County: 49.3 %Mahoning County: 71.2 %Medina County: 55.9 %Miami County: 63.1 %Monroe County: 96.7 %Montgomery County: 79.2 %Noble County: 62.1 %Ottawa County: 100 %Portage County: 60 %Preble County: 61.2 %Richland County: 98.3 %Sandusky County: 89 %Scioto County: 97.1 %Seneca County: 92.2 %Stark County: 68.8 %Summit County: 78.6 %Trumbull County: 65.9 %Warren County: 51.9 %Washington County: 53.9 %Wyandot County: 93.7 %
  • Under 55
  • 55 to 63
  • 63 to 66
  • 66 to 78
  • 78 to 96
  • 96 and over
  • No data
%, 1995. 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, 1995

Athens County: 100 %Athens County100Hancock County: 100 %Hancock County100Ottawa County: 100 %Ottawa County100Adams County: 98.7 %Adams County98.7Greene County: 98.3 %Greene County98.3Richland County: 98.3 %Richland County98.3Scioto County: 97.1 %Scioto County97.1Monroe County: 96.7 %Monroe County96.7Wyandot County: 93.7 %Wyandot County93.7Seneca County: 92.2 %Seneca County92.2Belmont County: 90.5 %Belmont County90.5Sandusky County: 89 %Sandusky County89Columbiana County: 82.3 %Columbiana County82.3Montgomery County: 79.2 %Montgomery County79.2Summit County: 78.6 %Summit County78.6Lucas County: 77 %Lucas County77Franklin County: 75.9 %Franklin County75.9Lorain County: 75.9 %Lorain County75.9Lake County: 74.8 %Lake County74.8Mahoning County: 71.2 %Mahoning County71.2Crawford County: 70.7 %Crawford County70.7Stark County: 68.8 %Stark County68.8Butler County: 66.3 %Butler County66.3Trumbull County: 65.9 %Trumbull County65.9Allen County: 65.1 %Allen County65.1Hamilton County: 64.1 %Hamilton County64.1Ashtabula County: 63.6 %Ashtabula County63.6Knox County: 63.1 %Knox County63.1Miami County: 63.1 %Miami County63.1Jefferson County: 63 %Jefferson County63Fayette County: 62.8 %Fayette County62.8Noble County: 62.1 %Noble County62.1Lawrence County: 61.9 %Lawrence County61.9Preble County: 61.2 %Preble County61.2Portage County: 60 %Portage County60Medina County: 55.9 %Medina County55.9Clermont County: 55.4 %Clermont County55.4Cuyahoga County: 55.1 %Cuyahoga County55.1Logan County: 54.1 %Logan County54.1Washington County: 53.9 %Washington County53.9Licking County: 51.9 %Licking County51.9Warren County: 51.9 %Warren County51.9Madison County: 49.3 %Madison County49.3Clark County: 48.1 %Clark County48.1Clinton County: 47.3 %Clinton County47.3Athens County: 100 %Athens County100Hancock County: 100 %Hancock County100Ottawa County: 100 %Ottawa County100Adams County: 98.7 %Adams County98.7Greene County: 98.3 %Greene County98.3Richland County: 98.3 %Richland County98.3Scioto County: 97.1 %Scioto County97.1Monroe County: 96.7 %Monroe County96.7Wyandot County: 93.7 %Wyandot County93.7Seneca County: 92.2 %Seneca County92.2Belmont County: 90.5 %Belmont County90.5Sandusky County: 89 %Sandusky County89Columbiana County: 82.3 %Columbiana County82.3Montgomery County: 79.2 %Montgomery County79.2Summit County: 78.6 %Summit County78.6Lucas County: 77 %Lucas County77Franklin County: 75.9 %Franklin County75.9Lorain County: 75.9 %Lorain County75.9Lake County: 74.8 %Lake County74.8Mahoning County: 71.2 %Mahoning County71.2Crawford County: 70.7 %Crawford County70.7Stark County: 68.8 %Stark County68.8Butler County: 66.3 %Butler County66.3Trumbull County: 65.9 %Trumbull County65.9Allen County: 65.1 %Allen County65.1Hamilton County: 64.1 %Hamilton County64.1Ashtabula County: 63.6 %Ashtabula County63.6Knox County: 63.1 %Knox County63.1Miami County: 63.1 %Miami County63.1Jefferson County: 63 %Jefferson County63Fayette County: 62.8 %Fayette County62.8Noble County: 62.1 %Noble County62.1Lawrence County: 61.9 %Lawrence County61.9Preble County: 61.2 %Preble County61.2Portage County: 60 %Portage County60Medina County: 55.9 %Medina County55.9Clermont County: 55.4 %Clermont County55.4Cuyahoga County: 55.1 %Cuyahoga County55.1Logan County: 54.1 %Logan County54.1Washington County: 53.9 %Washington County53.9Licking County: 51.9 %Licking County51.9Warren County: 51.9 %Warren County51.9Madison County: 49.3 %Madison County49.3Clark County: 48.1 %Clark County48.1Clinton County: 47.3 %Clinton County47.3
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties1995 (%)Change on 1994
1Athens County100+3.6 pts
1Hancock County1000 pts
1Ottawa County1000 pts
4Adams County98.7-1.3 pts
5Greene County98.3+1.6 pts
5Richland County98.3+2.6 pts
7Scioto County97.1+5.5 pts
8Monroe County96.7+8.4 pts
9Wyandot County93.7-0.6 pts
10Seneca County92.2+1.5 pts
11Belmont County90.5+3.4 pts
12Sandusky County89+1.6 pts
13Columbiana County82.3+11.9 pts
14Montgomery County79.2+8.8 pts
15Summit County78.60 pts
16Lucas County77+0.3 pts
17Franklin County75.9+2.2 pts
17Lorain County75.9+0.6 pts
19Lake County74.80 pts
20Mahoning County71.2-11.8 pts
21Crawford County70.7-2.3 pts
22Stark County68.8-6.5 pts
23Butler County66.3-1.6 pts
24Trumbull County65.9-3.3 pts
25Allen County65.1+6.3 pts
26Hamilton County64.1-4.9 pts
27Ashtabula County63.6-8.1 pts
28Knox County63.1+3.1 pts
28Miami County63.1-22.3 pts
30Jefferson County63-4.7 pts
31Fayette County62.8-8.9 pts
32Noble County62.1-8.2 pts
33Lawrence County61.9-5.2 pts
34Preble County61.2-5.6 pts
35Portage County60-4.8 pts
36Medina County55.9-3.3 pts
37Clermont County55.4-3.2 pts
38Cuyahoga County55.1+8 pts
39Logan County54.1+4.3 pts
40Washington County53.9+1.8 pts
41Licking County51.9-3.9 pts
41Warren County51.9-2.2 pts
43Madison County49.3-6.6 pts
44Clark County48.1-4.2 pts
45Clinton County47.3-7.4 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. 13 counties with data in other periods have no value for 1995 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), 1995) [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), 1995. 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=1995. 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), 1995. 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=1995.

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), 1995 [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=1995 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_ohio_by_1995,
  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), 1995}},
  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=1995. 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), 1995
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=1995
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/ohio-counties?period=1995.
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 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}
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Questions

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

Athens County, with 100% in 1995, according to EPA.

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

Clinton County, with 47.3% in 1995.

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. 13 counties have no value for 1995 and are not ranked.

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

Counties in Ohio: more rankings