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

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

Christian County had the highest median Air Quality Index (US EPA) of 37 counties in 1994, at 54. Warren County had the lowest, at 18. The median was 41. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest54Christian County
Lowest18Warren County
Median4137 counties

Map of counties, 1994

Bell County: 38 indexBoone County: 46 indexBoyd County: 41 indexBullitt County: 36 indexCampbell County: 40 indexCarter County: 24 indexChristian County: 54 indexDaviess County: 36 indexEdmonson County: 43 indexFayette County: 41 indexFloyd County: 24 indexGraves County: 41 indexGreenup County: 45 indexHancock County: 46 indexHardin County: 44 indexHarlan County: 29 indexHenderson County: 39 indexJefferson County: 48 indexJessamine County: 44 indexKenton County: 42 indexLawrence County: 39 indexLivingston County: 46 indexMcCracken County: 36 indexMcLean County: 48 indexMadison County: 24 indexMarshall County: 24 indexMorgan County: 44 indexOldham County: 45 indexPerry County: 40 indexPike County: 43 indexPulaski County: 42 indexScott County: 50 indexSimpson County: 38 indexTrigg County: 43 indexWarren County: 18 indexWashington County: 44 indexWhitley County: 23 index
  • Under 29
  • 29 to 39
  • 39 to 41
  • 41 to 44
  • 44 to 46
  • 46 and over
  • No data
index, 1994. 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, 1994

Christian County: 54 indexChristian County54Scott County: 50 indexScott County50Jefferson County: 48 indexJefferson County48McLean County: 48 indexMcLean County48Boone County: 46 indexBoone County46Hancock County: 46 indexHancock County46Livingston County: 46 indexLivingston County46Greenup County: 45 indexGreenup County45Oldham County: 45 indexOldham County45Hardin County: 44 indexHardin County44Jessamine County: 44 indexJessamine County44Morgan County: 44 indexMorgan County44Washington County: 44 indexWashington County44Edmonson County: 43 indexEdmonson County43Pike County: 43 indexPike County43Trigg County: 43 indexTrigg County43Kenton County: 42 indexKenton County42Pulaski County: 42 indexPulaski County42Boyd County: 41 indexBoyd County41Fayette County: 41 indexFayette County41Graves County: 41 indexGraves County41Campbell County: 40 indexCampbell County40Perry County: 40 indexPerry County40Henderson County: 39 indexHenderson County39Lawrence County: 39 indexLawrence County39Bell County: 38 indexBell County38Simpson County: 38 indexSimpson County38Bullitt County: 36 indexBullitt County36Daviess County: 36 indexDaviess County36McCracken County: 36 indexMcCracken County36Harlan County: 29 indexHarlan County29Carter County: 24 indexCarter County24Floyd County: 24 indexFloyd County24Madison County: 24 indexMadison County24Marshall County: 24 indexMarshall County24Whitley County: 23 indexWhitley County23Warren County: 18 indexWarren County18Christian County: 54 indexChristian County54Scott County: 50 indexScott County50Jefferson County: 48 indexJefferson County48McLean County: 48 indexMcLean County48Boone County: 46 indexBoone County46Hancock County: 46 indexHancock County46Livingston County: 46 indexLivingston County46Greenup County: 45 indexGreenup County45Oldham County: 45 indexOldham County45Hardin County: 44 indexHardin County44Jessamine County: 44 indexJessamine County44Morgan County: 44 indexMorgan County44Washington County: 44 indexWashington County44Edmonson County: 43 indexEdmonson County43Pike County: 43 indexPike County43Trigg County: 43 indexTrigg County43Kenton County: 42 indexKenton County42Pulaski County: 42 indexPulaski County42Boyd County: 41 indexBoyd County41Fayette County: 41 indexFayette County41Graves County: 41 indexGraves County41Campbell County: 40 indexCampbell County40Perry County: 40 indexPerry County40Henderson County: 39 indexHenderson County39Lawrence County: 39 indexLawrence County39Bell County: 38 indexBell County38Simpson County: 38 indexSimpson County38Bullitt County: 36 indexBullitt County36Daviess County: 36 indexDaviess County36McCracken County: 36 indexMcCracken County36Harlan County: 29 indexHarlan County29Carter County: 24 indexCarter County24Floyd County: 24 indexFloyd County24Madison County: 24 indexMadison County24Marshall County: 24 indexMarshall County24Whitley County: 23 indexWhitley County23Warren County: 18 indexWarren County18
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties1994
index		Change on 1993
1Christian County54+13
2Scott County50+6
3Jefferson County48+7
3McLean County48+3
5Boone County46+2
5Hancock County46+3
5Livingston County46+2
8Greenup County45+1
8Oldham County45+2
10Hardin County440
10Jessamine County440
10Morgan County44+13
10Washington County44+2
14Edmonson County43+1
14Pike County430
14Trigg County43+19
17Kenton County42+2
17Pulaski County42-2
19Boyd County41+3
19Fayette County41+1
19Graves County41+3
22Campbell County40+4
22Perry County40-2
24Henderson County390
24Lawrence County39-2
26Bell County38-3
26Simpson County38+2
28Bullitt County360
28Daviess County360
28McCracken County36+5
31Harlan County290
32Carter County24+2
32Floyd County24+4
32Madison County24+5
32Marshall County24+2
36Whitley County23+3
37Warren County180

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 1994 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), 1994) [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), 1994. 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=1994. 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), 1994. 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=1994.

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), 1994 [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=1994 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_kentucky_by_1994,
  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), 1994}},
  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=1994. 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), 1994
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=1994
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/kentucky-counties?period=1994.
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)?

Christian County, with 54 in 1994, according to the U.S. Environmental Protection Agency.

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

Warren County, with 18 in 1994.

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 1994 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Kentucky: more rankings