Data / Rankings / Median Air Quality Index (US EPA) / Counties in Ohio

Counties in Ohio by median Air Quality Index (US EPA)

Cuyahoga County had the highest median Air Quality Index (US EPA) of 47 counties in 1992, at 47. Seneca County had the lowest, at 18. The median was 34. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest47Cuyahoga County
Lowest18Seneca County
Median3447 counties

Map of counties, 1992

Adams County: 19 indexAllen County: 41 indexAshtabula County: 42 indexAthens County: 19 indexBelmont County: 22 indexButler County: 38 indexClark County: 42 indexClermont County: 36 indexClinton County: 44 indexColumbiana County: 33 indexCrawford County: 37 indexCuyahoga County: 47 indexFayette County: 37 indexFranklin County: 34 indexGreene County: 21 indexHamilton County: 44 indexHancock County: 26 indexJackson County: 22 indexJefferson County: 44 indexKnox County: 41 indexLake County: 35 indexLawrence County: 36 indexLicking County: 46 indexLogan County: 45 indexLorain County: 32 indexLucas County: 31 indexMadison County: 44 indexMahoning County: 30 indexMedina County: 39 indexMontgomery County: 27 indexNoble County: 28 indexOttawa County: 22 indexPickaway County: 20 indexPortage County: 39 indexPreble County: 34 indexRichland County: 23 indexSandusky County: 28 indexScioto County: 28 indexSeneca County: 18 indexStark County: 33 indexSummit County: 30 indexTrumbull County: 40 indexTuscarawas County: 19 indexUnion County: 44 indexWarren County: 44 indexWashington County: 44 indexWyandot County: 21 index
  • Under 22
  • 22 to 29
  • 29 to 34
  • 34 to 39
  • 39 to 44
  • 44 and over
  • No data
index, 1992. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 1992

Cuyahoga County: 47 indexCuyahoga County47Licking County: 46 indexLicking County46Logan County: 45 indexLogan County45Clinton County: 44 indexClinton County44Hamilton County: 44 indexHamilton County44Jefferson County: 44 indexJefferson County44Madison County: 44 indexMadison County44Union County: 44 indexUnion County44Warren County: 44 indexWarren County44Washington County: 44 indexWashington County44Ashtabula County: 42 indexAshtabula County42Clark County: 42 indexClark County42Allen County: 41 indexAllen County41Knox County: 41 indexKnox County41Trumbull County: 40 indexTrumbull County40Medina County: 39 indexMedina County39Portage County: 39 indexPortage County39Butler County: 38 indexButler County38Crawford County: 37 indexCrawford County37Fayette County: 37 indexFayette County37Clermont County: 36 indexClermont County36Lawrence County: 36 indexLawrence County36Lake County: 35 indexLake County35Franklin County: 34 indexFranklin County34Preble County: 34 indexPreble County34Columbiana County: 33 indexColumbiana County33Stark County: 33 indexStark County33Lorain County: 32 indexLorain County32Lucas County: 31 indexLucas County31Mahoning County: 30 indexMahoning County30Summit County: 30 indexSummit County30Noble County: 28 indexNoble County28Sandusky County: 28 indexSandusky County28Scioto County: 28 indexScioto County28Montgomery County: 27 indexMontgomery County27Hancock County: 26 indexHancock County26Richland County: 23 indexRichland County23Belmont County: 22 indexBelmont County22Jackson County: 22 indexJackson County22Ottawa County: 22 indexOttawa County22Greene County: 21 indexGreene County21Wyandot County: 21 indexWyandot County21Pickaway County: 20 indexPickaway County20Adams County: 19 indexAdams County19Athens County: 19 indexAthens County19Tuscarawas County: 19 indexTuscarawas County19Seneca County: 18 indexSeneca County18Cuyahoga County: 47 indexCuyahoga County47Licking County: 46 indexLicking County46Logan County: 45 indexLogan County45Clinton County: 44 indexClinton County44Hamilton County: 44 indexHamilton County44Jefferson County: 44 indexJefferson County44Madison County: 44 indexMadison County44Union County: 44 indexUnion County44Warren County: 44 indexWarren County44Washington County: 44 indexWashington County44Ashtabula County: 42 indexAshtabula County42Clark County: 42 indexClark County42Allen County: 41 indexAllen County41Knox County: 41 indexKnox County41Trumbull County: 40 indexTrumbull County40Medina County: 39 indexMedina County39Portage County: 39 indexPortage County39Butler County: 38 indexButler County38Crawford County: 37 indexCrawford County37Fayette County: 37 indexFayette County37Clermont County: 36 indexClermont County36Lawrence County: 36 indexLawrence County36Lake County: 35 indexLake County35Franklin County: 34 indexFranklin County34Preble County: 34 indexPreble County34Columbiana County: 33 indexColumbiana County33Stark County: 33 indexStark County33Lorain County: 32 indexLorain County32Lucas County: 31 indexLucas County31Mahoning County: 30 indexMahoning County30Summit County: 30 indexSummit County30Noble County: 28 indexNoble County28Sandusky County: 28 indexSandusky County28Scioto County: 28 indexScioto County28Montgomery County: 27 indexMontgomery County27Hancock County: 26 indexHancock County26Richland County: 23 indexRichland County23Belmont County: 22 indexBelmont County22Jackson County: 22 indexJackson County22Ottawa County: 22 indexOttawa County22Greene County: 21 indexGreene County21Wyandot County: 21 indexWyandot County21Pickaway County: 20 indexPickaway County20Adams County: 19 indexAdams County19Athens County: 19 indexAthens County19Tuscarawas County: 19 indexTuscarawas County19Seneca County: 18 indexSeneca County18
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties1992
index		Change on 1991
1Cuyahoga County47-4
2Licking County46-8
3Logan County45-13
4Clinton County44-17
4Hamilton County44-3
4Jefferson County44-9
4Madison County44-6
4Union County44-14
4Warren County44-14
4Washington County44-5
11Ashtabula County42-4
11Clark County42-8
13Allen County41-8
13Knox County41-1
15Trumbull County40+14
16Medina County39-10
16Portage County39-15
18Butler County38-3
19Crawford County37+1
19Fayette County37-2
21Clermont County36-8
21Lawrence County36-12
23Lake County35+2
24Franklin County34-6
24Preble County34-24
26Columbiana County33+5
26Stark County33-3
28Lorain County32-2
29Lucas County31-1
30Mahoning County30-3
30Summit County30-6
32Noble County28-1
32Sandusky County280
32Scioto County28-2
35Montgomery County27-1
36Hancock County26-3
37Richland County230
38Belmont County220
38Jackson County22-8
38Ottawa County22+1
41Greene County210
41Wyandot County210
43Pickaway County20-2
44Adams County190
44Athens County190
44Tuscarawas County19n/a
47Seneca County18-3

Other periods

About this ranking

Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries.

More on how it is measured
  • The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide).
  • Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.

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. 11 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: median daily AQI. 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: median daily AQI (Counties in Ohio by median Air Quality Index (US EPA), 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: median daily AQI, Counties in Ohio by median Air Quality Index (US EPA), 1992. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/median-air-quality-index/ohio-counties?period=1992. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Ohio by median Air Quality Index (US EPA), 1992. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/median-air-quality-index/ohio-counties?period=1992.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Ohio by median Air Quality Index (US EPA), 1992 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/ohio-counties?period=1992 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_ohio_by_1992,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Ohio by median Air Quality Index (US EPA), 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/median-air-quality-index/ohio-counties?period=1992. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. 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: median daily AQI: Counties in Ohio by median Air Quality Index (US EPA), 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/median-air-quality-index/ohio-counties?period=1992
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/ohio-counties?period=1992.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Rank Counties in Ohio by median Air Quality Index (US EPA) using official data, and cite the source.
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Questions

Which county has the highest median Air Quality Index (US EPA)?

Cuyahoga County, with 47 in 1992, according to the U.S. Environmental Protection Agency.

Which county has the lowest median Air Quality Index (US EPA)?

Seneca County, with 18 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: median daily AQI. Retrieved 2026-10-12. 11 counties have no value for 1992 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Ohio: more rankings