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

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

McLean County had the highest median Air Quality Index (US EPA) of 37 counties in 1993, at 45. Warren County had the lowest, at 18. The median was 40. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest45McLean County
Lowest18Warren County
Median4037 counties

Map of counties, 1993

Bell County: 41 indexBoone County: 44 indexBoyd County: 38 indexBullitt County: 36 indexCampbell County: 36 indexCarter County: 22 indexChristian County: 41 indexDaviess County: 36 indexEdmonson County: 42 indexFayette County: 40 indexFloyd County: 20 indexGraves County: 38 indexGreenup County: 44 indexHancock County: 43 indexHardin County: 44 indexHarlan County: 29 indexHenderson County: 39 indexJefferson County: 41 indexJessamine County: 44 indexKenton County: 40 indexLawrence County: 41 indexLivingston County: 44 indexMcCracken County: 31 indexMcLean County: 45 indexMadison County: 19 indexMarshall County: 22 indexMorgan County: 31 indexOldham County: 43 indexPerry County: 42 indexPike County: 43 indexPulaski County: 44 indexScott County: 44 indexSimpson County: 36 indexTrigg County: 24 indexWarren County: 18 indexWashington County: 42 indexWhitley County: 20 index
  • Under 24
  • 24 to 36
  • 36 to 40
  • 40 to 42
  • 42 to 44
  • 44 and over
  • No data
index, 1993. 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, 1993

McLean County: 45 indexMcLean County45Boone County: 44 indexBoone County44Greenup County: 44 indexGreenup County44Hardin County: 44 indexHardin County44Jessamine County: 44 indexJessamine County44Livingston County: 44 indexLivingston County44Pulaski County: 44 indexPulaski County44Scott County: 44 indexScott County44Hancock County: 43 indexHancock County43Oldham County: 43 indexOldham County43Pike County: 43 indexPike County43Edmonson County: 42 indexEdmonson County42Perry County: 42 indexPerry County42Washington County: 42 indexWashington County42Bell County: 41 indexBell County41Christian County: 41 indexChristian County41Jefferson County: 41 indexJefferson County41Lawrence County: 41 indexLawrence County41Fayette County: 40 indexFayette County40Kenton County: 40 indexKenton County40Henderson County: 39 indexHenderson County39Boyd County: 38 indexBoyd County38Graves County: 38 indexGraves County38Bullitt County: 36 indexBullitt County36Campbell County: 36 indexCampbell County36Daviess County: 36 indexDaviess County36Simpson County: 36 indexSimpson County36McCracken County: 31 indexMcCracken County31Morgan County: 31 indexMorgan County31Harlan County: 29 indexHarlan County29Trigg County: 24 indexTrigg County24Carter County: 22 indexCarter County22Marshall County: 22 indexMarshall County22Floyd County: 20 indexFloyd County20Whitley County: 20 indexWhitley County20Madison County: 19 indexMadison County19Warren County: 18 indexWarren County18McLean County: 45 indexMcLean County45Boone County: 44 indexBoone County44Greenup County: 44 indexGreenup County44Hardin County: 44 indexHardin County44Jessamine County: 44 indexJessamine County44Livingston County: 44 indexLivingston County44Pulaski County: 44 indexPulaski County44Scott County: 44 indexScott County44Hancock County: 43 indexHancock County43Oldham County: 43 indexOldham County43Pike County: 43 indexPike County43Edmonson County: 42 indexEdmonson County42Perry County: 42 indexPerry County42Washington County: 42 indexWashington County42Bell County: 41 indexBell County41Christian County: 41 indexChristian County41Jefferson County: 41 indexJefferson County41Lawrence County: 41 indexLawrence County41Fayette County: 40 indexFayette County40Kenton County: 40 indexKenton County40Henderson County: 39 indexHenderson County39Boyd County: 38 indexBoyd County38Graves County: 38 indexGraves County38Bullitt County: 36 indexBullitt County36Campbell County: 36 indexCampbell County36Daviess County: 36 indexDaviess County36Simpson County: 36 indexSimpson County36McCracken County: 31 indexMcCracken County31Morgan County: 31 indexMorgan County31Harlan County: 29 indexHarlan County29Trigg County: 24 indexTrigg County24Carter County: 22 indexCarter County22Marshall County: 22 indexMarshall County22Floyd County: 20 indexFloyd County20Whitley County: 20 indexWhitley County20Madison County: 19 indexMadison County19Warren County: 18 indexWarren County18
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties1993
index		Change on 1992
1McLean County45+1
2Boone County44+4
2Greenup County44+3
2Hardin County44+5
2Jessamine County44+3
2Livingston County44-1
2Pulaski County44+6
2Scott County44n/a
9Hancock County43-1
9Oldham County43+6
9Pike County43+6
12Edmonson County42+2
12Perry County42+4
12Washington County420
15Bell County41+7
15Christian County41n/a
15Jefferson County41+3
15Lawrence County410
19Fayette County40+3
19Kenton County40+5
21Henderson County39+1
22Boyd County38+1
22Graves County38-1
24Bullitt County36+2
24Campbell County36+4
24Daviess County36+1
24Simpson County360
28McCracken County31-5
28Morgan County31n/a
30Harlan County29-1
31Trigg County24n/a
32Carter County22-1
32Marshall County22+2
34Floyd County20-3
34Whitley County20-1
36Madison County19-4
37Warren County18-1

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. 18 counties with data in other periods have no value for 1993 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 Kentucky by median Air Quality Index (US EPA), 1993) [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 Kentucky by median Air Quality Index (US EPA), 1993. 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/kentucky-counties?period=1993. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Kentucky by median Air Quality Index (US EPA), 1993. 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/kentucky-counties?period=1993.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Kentucky by median Air Quality Index (US EPA), 1993 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/kentucky-counties?period=1993 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_kentucky_by_1993,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Kentucky by median Air Quality Index (US EPA), 1993}},
  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/kentucky-counties?period=1993. 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 Kentucky by median Air Quality Index (US EPA), 1993
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/kentucky-counties?period=1993
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/kentucky-counties?period=1993.
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 Kentucky 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)?

McLean County, with 45 in 1993, according to the U.S. Environmental Protection Agency.

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

Warren County, with 18 in 1993.

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. 18 counties have no value for 1993 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Kentucky: more rankings