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

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

Carter County had the highest median Air Quality Index (US EPA) of 37 counties in 1998, at 64. Warren County had the lowest, at 17. The median was 43. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest64Carter County
Lowest17Warren County
Median4337 counties

Map of counties, 1998

Bell County: 35 indexBoone County: 45 indexBoyd County: 33 indexBullitt County: 38 indexCampbell County: 34 indexCarter County: 64 indexChristian County: 58 indexDaviess County: 35 indexEdmonson County: 48 indexFayette County: 36 indexFloyd County: 17 indexGraves County: 51 indexGreenup County: 51 indexHancock County: 64 indexHardin County: 44 indexHarlan County: 21 indexHenderson County: 39 indexJefferson County: 43 indexJessamine County: 47 indexKenton County: 38 indexLawrence County: 38 indexLivingston County: 58 indexMcCracken County: 40 indexMcLean County: 51 indexMadison County: 20 indexMarshall County: 24 indexMorgan County: 44 indexOldham County: 48 indexPerry County: 36 indexPike County: 44 indexPulaski County: 48 indexScott County: 44 indexSimpson County: 40 indexTrigg County: 44 indexWarren County: 17 indexWashington County: 44 indexWhitley County: 20 index
  • Under 33
  • 33 to 38
  • 38 to 43
  • 43 to 44
  • 44 to 51
  • 51 and over
  • No data
index, 1998. 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, 1998

Carter County: 64 indexCarter County64Hancock County: 64 indexHancock County64Christian County: 58 indexChristian County58Livingston County: 58 indexLivingston County58Graves County: 51 indexGraves County51Greenup County: 51 indexGreenup County51McLean County: 51 indexMcLean County51Edmonson County: 48 indexEdmonson County48Oldham County: 48 indexOldham County48Pulaski County: 48 indexPulaski County48Jessamine County: 47 indexJessamine County47Boone County: 45 indexBoone County45Hardin County: 44 indexHardin County44Morgan County: 44 indexMorgan County44Pike County: 44 indexPike County44Scott County: 44 indexScott County44Trigg County: 44 indexTrigg County44Washington County: 44 indexWashington County44Jefferson County: 43 indexJefferson County43McCracken County: 40 indexMcCracken County40Simpson County: 40 indexSimpson County40Henderson County: 39 indexHenderson County39Bullitt County: 38 indexBullitt County38Kenton County: 38 indexKenton County38Lawrence County: 38 indexLawrence County38Fayette County: 36 indexFayette County36Perry County: 36 indexPerry County36Bell County: 35 indexBell County35Daviess County: 35 indexDaviess County35Campbell County: 34 indexCampbell County34Boyd County: 33 indexBoyd County33Marshall County: 24 indexMarshall County24Harlan County: 21 indexHarlan County21Madison County: 20 indexMadison County20Whitley County: 20 indexWhitley County20Floyd County: 17 indexFloyd County17Warren County: 17 indexWarren County17Carter County: 64 indexCarter County64Hancock County: 64 indexHancock County64Christian County: 58 indexChristian County58Livingston County: 58 indexLivingston County58Graves County: 51 indexGraves County51Greenup County: 51 indexGreenup County51McLean County: 51 indexMcLean County51Edmonson County: 48 indexEdmonson County48Oldham County: 48 indexOldham County48Pulaski County: 48 indexPulaski County48Jessamine County: 47 indexJessamine County47Boone County: 45 indexBoone County45Hardin County: 44 indexHardin County44Morgan County: 44 indexMorgan County44Pike County: 44 indexPike County44Scott County: 44 indexScott County44Trigg County: 44 indexTrigg County44Washington County: 44 indexWashington County44Jefferson County: 43 indexJefferson County43McCracken County: 40 indexMcCracken County40Simpson County: 40 indexSimpson County40Henderson County: 39 indexHenderson County39Bullitt County: 38 indexBullitt County38Kenton County: 38 indexKenton County38Lawrence County: 38 indexLawrence County38Fayette County: 36 indexFayette County36Perry County: 36 indexPerry County36Bell County: 35 indexBell County35Daviess County: 35 indexDaviess County35Campbell County: 34 indexCampbell County34Boyd County: 33 indexBoyd County33Marshall County: 24 indexMarshall County24Harlan County: 21 indexHarlan County21Madison County: 20 indexMadison County20Whitley County: 20 indexWhitley County20Floyd County: 17 indexFloyd County17Warren County: 17 indexWarren County17
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties1998
index		Change on 1997
1Carter County64n/a
1Hancock County64+19
3Christian County58+10
3Livingston County58+14
5Graves County51+11
5Greenup County51+11
5McLean County51+9
8Edmonson County48+4
8Oldham County48+5
8Pulaski County48+8
11Jessamine County47+6
12Boone County45+5
13Hardin County44+8
13Morgan County44+3
13Pike County44+6
13Scott County44+3
13Trigg County44+3
13Washington County44+2
19Jefferson County43+1
20McCracken County40+5
20Simpson County40+4
22Henderson County39+3
23Bullitt County38+3
23Kenton County38+2
23Lawrence County38+7
26Fayette County36-1
26Perry County360
28Bell County35+1
28Daviess County350
30Campbell County34-1
31Boyd County33-4
32Marshall County24+8
33Harlan County21+1
34Madison County200
34Whitley County20-2
36Floyd County17-1
36Warren County170

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 1998 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), 1998) [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), 1998. 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=1998. 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), 1998. 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=1998.

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), 1998 [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=1998 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_kentucky_by_1998,
  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), 1998}},
  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=1998. 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), 1998
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=1998
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/kentucky-counties?period=1998.
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)?

Carter County, with 64 in 1998, according to the U.S. Environmental Protection Agency.

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

Warren County, with 17 in 1998.

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 1998 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Kentucky: more rankings