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

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

Jefferson County had the highest median Air Quality Index (US EPA) of 36 counties in 2000, at 66. Whitley County had the lowest, at 20. The median was 45. Source: the U.S. Environmental Protection Agency.

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Highest66Jefferson County
Lowest20Whitley County
Median4536 counties

Map of counties, 2000

Bell County: 44 indexBoone County: 41 indexBoyd County: 48 indexBullitt County: 45 indexCampbell County: 47 indexCarter County: 51 indexChristian County: 58 indexDaviess County: 39 indexEdmonson County: 46 indexFayette County: 45 indexFranklin County: 61 indexGraves County: 46 indexGreenup County: 45 indexHancock County: 44 indexHardin County: 50 indexHarlan County: 24 indexHenderson County: 45 indexJefferson County: 66 indexJessamine County: 45 indexKenton County: 46 indexLivingston County: 50 indexMcCracken County: 46 indexMcLean County: 44 indexMadison County: 61 indexMarshall County: 22 indexMorgan County: 43 indexOldham County: 44 indexPerry County: 41 indexPike County: 46 indexPulaski County: 48 indexScott County: 37 indexSimpson County: 45 indexTrigg County: 43 indexWarren County: 50 indexWashington County: 44 indexWhitley County: 20 index
  • Under 41
  • 41 to 44
  • 44 to 45
  • 45 to 46
  • 46 to 50
  • 50 and over
  • No data
index, 2000. 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, 2000

Jefferson County: 66 indexJefferson County66Franklin County: 61 indexFranklin County61Madison County: 61 indexMadison County61Christian County: 58 indexChristian County58Carter County: 51 indexCarter County51Hardin County: 50 indexHardin County50Livingston County: 50 indexLivingston County50Warren County: 50 indexWarren County50Boyd County: 48 indexBoyd County48Pulaski County: 48 indexPulaski County48Campbell County: 47 indexCampbell County47Edmonson County: 46 indexEdmonson County46Graves County: 46 indexGraves County46Kenton County: 46 indexKenton County46McCracken County: 46 indexMcCracken County46Pike County: 46 indexPike County46Bullitt County: 45 indexBullitt County45Fayette County: 45 indexFayette County45Greenup County: 45 indexGreenup County45Henderson County: 45 indexHenderson County45Jessamine County: 45 indexJessamine County45Simpson County: 45 indexSimpson County45Bell County: 44 indexBell County44Hancock County: 44 indexHancock County44McLean County: 44 indexMcLean County44Oldham County: 44 indexOldham County44Washington County: 44 indexWashington County44Morgan County: 43 indexMorgan County43Trigg County: 43 indexTrigg County43Boone County: 41 indexBoone County41Perry County: 41 indexPerry County41Daviess County: 39 indexDaviess County39Scott County: 37 indexScott County37Harlan County: 24 indexHarlan County24Marshall County: 22 indexMarshall County22Whitley County: 20 indexWhitley County20Jefferson County: 66 indexJefferson County66Franklin County: 61 indexFranklin County61Madison County: 61 indexMadison County61Christian County: 58 indexChristian County58Carter County: 51 indexCarter County51Hardin County: 50 indexHardin County50Livingston County: 50 indexLivingston County50Warren County: 50 indexWarren County50Boyd County: 48 indexBoyd County48Pulaski County: 48 indexPulaski County48Campbell County: 47 indexCampbell County47Edmonson County: 46 indexEdmonson County46Graves County: 46 indexGraves County46Kenton County: 46 indexKenton County46McCracken County: 46 indexMcCracken County46Pike County: 46 indexPike County46Bullitt County: 45 indexBullitt County45Fayette County: 45 indexFayette County45Greenup County: 45 indexGreenup County45Henderson County: 45 indexHenderson County45Jessamine County: 45 indexJessamine County45Simpson County: 45 indexSimpson County45Bell County: 44 indexBell County44Hancock County: 44 indexHancock County44McLean County: 44 indexMcLean County44Oldham County: 44 indexOldham County44Washington County: 44 indexWashington County44Morgan County: 43 indexMorgan County43Trigg County: 43 indexTrigg County43Boone County: 41 indexBoone County41Perry County: 41 indexPerry County41Daviess County: 39 indexDaviess County39Scott County: 37 indexScott County37Harlan County: 24 indexHarlan County24Marshall County: 22 indexMarshall County22Whitley County: 20 indexWhitley County20
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2000
index		Change on 1999
1Jefferson County66-2
2Franklin County61+4
2Madison County61+3
4Christian County58-3
5Carter County51-9
6Hardin County50-11
6Livingston County50-17
6Warren County50-11
9Boyd County48-1
9Pulaski County48-13
11Campbell County47+1
12Edmonson County46-4
12Graves County46-18
12Kenton County46+1
12McCracken County46-2
12Pike County46-15
17Bullitt County45-4
17Fayette County45-5
17Greenup County45-5
17Henderson County45+1
17Jessamine County45-3
17Simpson County45+5
23Bell County44+5
23Hancock County44-17
23McLean County44-10
23Oldham County44-46
23Washington County44-2
28Morgan County43-4
28Trigg County43-5
30Boone County41-7
30Perry County41-3
32Daviess County39-7
33Scott County37-13
34Harlan County24-1
35Marshall County22-7
36Whitley County20-3

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. 19 counties with data in other periods have no value for 2000 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), 2000) [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), 2000. 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=2000. 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), 2000. 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=2000.

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), 2000 [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=2000 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_kentucky_by_2000,
  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), 2000}},
  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=2000. 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), 2000
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=2000
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/kentucky-counties?period=2000.
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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Questions

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

Jefferson County, with 66 in 2000, according to the U.S. Environmental Protection Agency.

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

Whitley County, with 20 in 2000.

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. 19 counties have no value for 2000 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Kentucky: more rankings