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 38 counties in 2002, at 65. Whitley County had the lowest, at 15. The median was 44. Source: the U.S. Environmental Protection Agency.

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Highest65Jefferson County
Lowest15Whitley County
Median4438 counties

Map of counties, 2002

Bell County: 50 indexBoone County: 43 indexBoyd County: 50 indexBullitt County: 44 indexCampbell County: 43 indexCarter County: 51 indexChristian County: 51 indexDaviess County: 42 indexEdmonson County: 44 indexFayette County: 45 indexFranklin County: 56 indexGraves County: 41 indexGreenup County: 42 indexHancock County: 48 indexHardin County: 51 indexHarlan County: 21 indexHenderson County: 49 indexJefferson County: 65 indexJessamine County: 42 indexKenton County: 45 indexLaurel County: 57 indexLivingston County: 45 indexMcCracken County: 41 indexMcLean County: 45 indexMadison County: 56 indexMarshall County: 18 indexMorgan County: 40 indexMuhlenberg County: 35 indexOldham County: 44 indexPerry County: 47 indexPike County: 43 indexPulaski County: 41 indexScott County: 37 indexSimpson County: 43 indexTrigg County: 43 indexWarren County: 47 indexWashington County: 41 indexWhitley County: 15 index
  • Under 41
  • 41 to 42
  • 42 to 44
  • 44 to 46
  • 46 to 51
  • 51 and over
  • No data
index, 2002. 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, 2002

Jefferson County: 65 indexJefferson County65Laurel County: 57 indexLaurel County57Franklin County: 56 indexFranklin County56Madison County: 56 indexMadison County56Carter County: 51 indexCarter County51Christian County: 51 indexChristian County51Hardin County: 51 indexHardin County51Bell County: 50 indexBell County50Boyd County: 50 indexBoyd County50Henderson County: 49 indexHenderson County49Hancock County: 48 indexHancock County48Perry County: 47 indexPerry County47Warren County: 47 indexWarren County47Fayette County: 45 indexFayette County45Kenton County: 45 indexKenton County45Livingston County: 45 indexLivingston County45McLean County: 45 indexMcLean County45Bullitt County: 44 indexBullitt County44Edmonson County: 44 indexEdmonson County44Oldham County: 44 indexOldham County44Boone County: 43 indexBoone County43Campbell County: 43 indexCampbell County43Pike County: 43 indexPike County43Simpson County: 43 indexSimpson County43Trigg County: 43 indexTrigg County43Daviess County: 42 indexDaviess County42Greenup County: 42 indexGreenup County42Jessamine County: 42 indexJessamine County42Graves County: 41 indexGraves County41McCracken County: 41 indexMcCracken County41Pulaski County: 41 indexPulaski County41Washington County: 41 indexWashington County41Morgan County: 40 indexMorgan County40Scott County: 37 indexScott County37Muhlenberg County: 35 indexMuhlenberg County35Harlan County: 21 indexHarlan County21Marshall County: 18 indexMarshall County18Whitley County: 15 indexWhitley County15Jefferson County: 65 indexJefferson County65Laurel County: 57 indexLaurel County57Franklin County: 56 indexFranklin County56Madison County: 56 indexMadison County56Carter County: 51 indexCarter County51Christian County: 51 indexChristian County51Hardin County: 51 indexHardin County51Bell County: 50 indexBell County50Boyd County: 50 indexBoyd County50Henderson County: 49 indexHenderson County49Hancock County: 48 indexHancock County48Perry County: 47 indexPerry County47Warren County: 47 indexWarren County47Fayette County: 45 indexFayette County45Kenton County: 45 indexKenton County45Livingston County: 45 indexLivingston County45McLean County: 45 indexMcLean County45Bullitt County: 44 indexBullitt County44Edmonson County: 44 indexEdmonson County44Oldham County: 44 indexOldham County44Boone County: 43 indexBoone County43Campbell County: 43 indexCampbell County43Pike County: 43 indexPike County43Simpson County: 43 indexSimpson County43Trigg County: 43 indexTrigg County43Daviess County: 42 indexDaviess County42Greenup County: 42 indexGreenup County42Jessamine County: 42 indexJessamine County42Graves County: 41 indexGraves County41McCracken County: 41 indexMcCracken County41Pulaski County: 41 indexPulaski County41Washington County: 41 indexWashington County41Morgan County: 40 indexMorgan County40Scott County: 37 indexScott County37Muhlenberg County: 35 indexMuhlenberg County35Harlan County: 21 indexHarlan County21Marshall County: 18 indexMarshall County18Whitley County: 15 indexWhitley County15
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2002
index		Change on 2001
1Jefferson County65-4
2Laurel County57n/a
3Franklin County56-1
3Madison County560
5Carter County51+1
5Christian County51-3
5Hardin County51-2
8Bell County50+5
8Boyd County50+2
10Henderson County49+5
11Hancock County48+4
12Perry County47+3
12Warren County47+1
14Fayette County45-3
14Kenton County450
14Livingston County45-3
14McLean County450
18Bullitt County44-5
18Edmonson County440
18Oldham County44-2
21Boone County430
21Campbell County43-1
21Pike County43-2
21Simpson County43-3
21Trigg County43-1
26Daviess County420
26Greenup County42-6
26Jessamine County42-2
29Graves County41+2
29McCracken County41-4
29Pulaski County41-3
29Washington County41-3
33Morgan County40-3
34Scott County37+2
35Muhlenberg County35-12
36Harlan County21-3
37Marshall County18-1
38Whitley County15-4

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. 17 counties with data in other periods have no value for 2002 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), 2002) [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), 2002. 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=2002. 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), 2002. 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=2002.

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), 2002 [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=2002 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_kentucky_by_2002,
  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), 2002}},
  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=2002. 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), 2002
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=2002
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/kentucky-counties?period=2002.
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)?

Jefferson County, with 65 in 2002, according to the U.S. Environmental Protection Agency.

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

Whitley County, with 15 in 2002.

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. 17 counties have no value for 2002 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Kentucky: more rankings