Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in Kentucky

Counties in Kentucky by share of days with good air quality (US EPA AQI)

Harlan County had the highest share of days with good air quality (US EPA AQI) of 36 counties in 2000, at 98.3%. Jefferson County had the lowest, at 10.7%. The median was 59.6%. Source: EPA.

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Highest98.3Harlan County
Lowest10.7Jefferson County
Median59.636 counties

Map of counties, 2000

Bell County: 62.8 %Boone County: 77.6 %Boyd County: 54.6 %Bullitt County: 58.6 %Campbell County: 57.5 %Carter County: 48.2 %Christian County: 38.1 %Daviess County: 67.9 %Edmonson County: 58.7 %Fayette County: 57.9 %Franklin County: 19.1 %Graves County: 60.5 %Greenup County: 64.3 %Hancock County: 67.2 %Hardin County: 50.8 %Harlan County: 98.3 %Henderson County: 56 %Jefferson County: 10.7 %Jessamine County: 67.5 %Kenton County: 58.5 %Livingston County: 52.2 %McCracken County: 55.5 %McLean County: 67.4 %Madison County: 18.3 %Marshall County: 95.1 %Morgan County: 67.1 %Oldham County: 68.3 %Perry County: 71.1 %Pike County: 55.6 %Pulaski County: 56.7 %Scott County: 84.1 %Simpson County: 66 %Trigg County: 65.2 %Warren County: 50.8 %Washington County: 62.3 %Whitley County: 94.9 %
  • Under 51
  • 51 to 56
  • 56 to 60
  • 60 to 66
  • 66 to 69
  • 69 and over
  • No data
%, 2000. Hatched areas have no value for this period. Source: Invokely calculation with data from EPA. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2000

Harlan County: 98.3 %Harlan County98.3Marshall County: 95.1 %Marshall County95.1Whitley County: 94.9 %Whitley County94.9Scott County: 84.1 %Scott County84.1Boone County: 77.6 %Boone County77.6Perry County: 71.1 %Perry County71.1Oldham County: 68.3 %Oldham County68.3Daviess County: 67.9 %Daviess County67.9Jessamine County: 67.5 %Jessamine County67.5McLean County: 67.4 %McLean County67.4Hancock County: 67.2 %Hancock County67.2Morgan County: 67.1 %Morgan County67.1Simpson County: 66 %Simpson County66Trigg County: 65.2 %Trigg County65.2Greenup County: 64.3 %Greenup County64.3Bell County: 62.8 %Bell County62.8Washington County: 62.3 %Washington County62.3Graves County: 60.5 %Graves County60.5Edmonson County: 58.7 %Edmonson County58.7Bullitt County: 58.6 %Bullitt County58.6Kenton County: 58.5 %Kenton County58.5Fayette County: 57.9 %Fayette County57.9Campbell County: 57.5 %Campbell County57.5Pulaski County: 56.7 %Pulaski County56.7Henderson County: 56 %Henderson County56Pike County: 55.6 %Pike County55.6McCracken County: 55.5 %McCracken County55.5Boyd County: 54.6 %Boyd County54.6Livingston County: 52.2 %Livingston County52.2Hardin County: 50.8 %Hardin County50.8Warren County: 50.8 %Warren County50.8Carter County: 48.2 %Carter County48.2Christian County: 38.1 %Christian County38.1Franklin County: 19.1 %Franklin County19.1Madison County: 18.3 %Madison County18.3Jefferson County: 10.7 %Jefferson County10.7Harlan County: 98.3 %Harlan County98.3Marshall County: 95.1 %Marshall County95.1Whitley County: 94.9 %Whitley County94.9Scott County: 84.1 %Scott County84.1Boone County: 77.6 %Boone County77.6Perry County: 71.1 %Perry County71.1Oldham County: 68.3 %Oldham County68.3Daviess County: 67.9 %Daviess County67.9Jessamine County: 67.5 %Jessamine County67.5McLean County: 67.4 %McLean County67.4Hancock County: 67.2 %Hancock County67.2Morgan County: 67.1 %Morgan County67.1Simpson County: 66 %Simpson County66Trigg County: 65.2 %Trigg County65.2Greenup County: 64.3 %Greenup County64.3Bell County: 62.8 %Bell County62.8Washington County: 62.3 %Washington County62.3Graves County: 60.5 %Graves County60.5Edmonson County: 58.7 %Edmonson County58.7Bullitt County: 58.6 %Bullitt County58.6Kenton County: 58.5 %Kenton County58.5Fayette County: 57.9 %Fayette County57.9Campbell County: 57.5 %Campbell County57.5Pulaski County: 56.7 %Pulaski County56.7Henderson County: 56 %Henderson County56Pike County: 55.6 %Pike County55.6McCracken County: 55.5 %McCracken County55.5Boyd County: 54.6 %Boyd County54.6Livingston County: 52.2 %Livingston County52.2Hardin County: 50.8 %Hardin County50.8Warren County: 50.8 %Warren County50.8Carter County: 48.2 %Carter County48.2Christian County: 38.1 %Christian County38.1Franklin County: 19.1 %Franklin County19.1Madison County: 18.3 %Madison County18.3Jefferson County: 10.7 %Jefferson County10.7
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2000 (%)Change on 1999
1Harlan County98.3-1.7 pts
2Marshall County95.1+4.7 pts
3Whitley County94.9-3.3 pts
4Scott County84.1+31.3 pts
5Boone County77.6+20.1 pts
6Perry County71.1-2.5 pts
7Oldham County68.3+39.2 pts
8Daviess County67.9+13.1 pts
9Jessamine County67.5+12.4 pts
10McLean County67.4+19.1 pts
11Hancock County67.2+22.8 pts
12Morgan County67.1+13.4 pts
13Simpson County66+4.1 pts
14Trigg County65.2+9.4 pts
15Greenup County64.3+10.6 pts
16Bell County62.8-3.4 pts
17Washington County62.3+5.8 pts
18Graves County60.5+18 pts
19Edmonson County58.7+8.1 pts
20Bullitt County58.6+6.5 pts
21Kenton County58.5+0.7 pts
22Fayette County57.9+7.2 pts
23Campbell County57.5+0.1 pts
24Pulaski County56.7+14.1 pts
25Henderson County56-3.7 pts
26Pike County55.6+22.5 pts
27McCracken County55.5+2.1 pts
28Boyd County54.6+2 pts
29Livingston County52.2+12 pts
30Hardin County50.8+17 pts
30Warren County50.8+29.7 pts
32Carter County48.2+12.9 pts
33Christian County38.1+5.9 pts
34Franklin County19.1-4.5 pts
35Madison County18.3-8.8 pts
36Jefferson County10.7-4.1 pts

Other periods

About this ranking

Days with a daily Air Quality Index of 0 to 50 (good) as a percentage of the days of the year with an AQI in a US county. Calculated by Invokely from the day counts in the EPA AirData annual summaries; both counts are stored with each value.

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: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts (Counties in Kentucky by share of days with good air quality (US EPA AQI), 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: good days as a share of days with an AQI, calculated with stored counts, Counties in Kentucky by share of days with good air quality (US EPA AQI), 2000. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/good-air-quality-days-share/kentucky-counties?period=2000. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Counties in Kentucky by share of days with good air quality (US EPA AQI), 2000. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/good-air-quality-days-share/kentucky-counties?period=2000.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Counties in Kentucky by share of days with good air quality (US EPA AQI), 2000 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/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: good days as a share of days with an AQI, calculated with stored counts: Counties in Kentucky by share of days with good air quality (US EPA AQI), 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/good-air-quality-days-share/kentucky-counties?period=2000. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts: Counties in Kentucky by share of days with good air quality (US EPA AQI), 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/good-air-quality-days-share/kentucky-counties?period=2000
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/kentucky-counties?period=2000.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. 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 share of days with good air quality (US EPA AQI)?

Harlan County, with 98.3% in 2000, according to EPA.

Which county has the lowest share of days with good air quality (US EPA AQI)?

Jefferson County, with 10.7% 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: good days as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 19 counties have no value for 2000 and are not ranked.

Share of days with good air quality (US EPA AQI): other rankings

Counties in Kentucky: more rankings