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 2003, at 100%. Jefferson County had the lowest, at 13.4%. The median was 64.5%. Source: EPA.

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Highest100Harlan County
Lowest13.4Jefferson County
Median64.536 counties

Map of counties, 2003

Bell County: 60.4 %Boone County: 76.4 %Boyd County: 55.2 %Bullitt County: 66.6 %Campbell County: 63.9 %Carter County: 59.7 %Christian County: 44.5 %Daviess County: 66.3 %Edmonson County: 65.6 %Fayette County: 58.9 %Franklin County: 33.6 %Graves County: 65.3 %Greenup County: 67.2 %Hancock County: 61.6 %Hardin County: 52.1 %Harlan County: 100 %Henderson County: 59 %Jefferson County: 13.4 %Jessamine County: 72.1 %Kenton County: 60.2 %Laurel County: 18 %Livingston County: 57.7 %McCracken County: 64.1 %McLean County: 62.4 %Madison County: 30.2 %Marshall County: 100 %Morgan County: 79.4 %Oldham County: 69 %Perry County: 66.4 %Pike County: 73.4 %Pulaski County: 78.1 %Scott County: 87.3 %Simpson County: 65.3 %Trigg County: 64.9 %Warren County: 59.1 %Washington County: 76.1 %
  • Under 55
  • 55 to 60
  • 60 to 65
  • 65 to 66
  • 66 to 76
  • 76 and over
  • No data
%, 2003. 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, 2003

Harlan County: 100 %Harlan County100Marshall County: 100 %Marshall County100Scott County: 87.3 %Scott County87.3Morgan County: 79.4 %Morgan County79.4Pulaski County: 78.1 %Pulaski County78.1Boone County: 76.4 %Boone County76.4Washington County: 76.1 %Washington County76.1Pike County: 73.4 %Pike County73.4Jessamine County: 72.1 %Jessamine County72.1Oldham County: 69 %Oldham County69Greenup County: 67.2 %Greenup County67.2Bullitt County: 66.6 %Bullitt County66.6Perry County: 66.4 %Perry County66.4Daviess County: 66.3 %Daviess County66.3Edmonson County: 65.6 %Edmonson County65.6Graves County: 65.3 %Graves County65.3Simpson County: 65.3 %Simpson County65.3Trigg County: 64.9 %Trigg County64.9McCracken County: 64.1 %McCracken County64.1Campbell County: 63.9 %Campbell County63.9McLean County: 62.4 %McLean County62.4Hancock County: 61.6 %Hancock County61.6Bell County: 60.4 %Bell County60.4Kenton County: 60.2 %Kenton County60.2Carter County: 59.7 %Carter County59.7Warren County: 59.1 %Warren County59.1Henderson County: 59 %Henderson County59Fayette County: 58.9 %Fayette County58.9Livingston County: 57.7 %Livingston County57.7Boyd County: 55.2 %Boyd County55.2Hardin County: 52.1 %Hardin County52.1Christian County: 44.5 %Christian County44.5Franklin County: 33.6 %Franklin County33.6Madison County: 30.2 %Madison County30.2Laurel County: 18 %Laurel County18Jefferson County: 13.4 %Jefferson County13.4Harlan County: 100 %Harlan County100Marshall County: 100 %Marshall County100Scott County: 87.3 %Scott County87.3Morgan County: 79.4 %Morgan County79.4Pulaski County: 78.1 %Pulaski County78.1Boone County: 76.4 %Boone County76.4Washington County: 76.1 %Washington County76.1Pike County: 73.4 %Pike County73.4Jessamine County: 72.1 %Jessamine County72.1Oldham County: 69 %Oldham County69Greenup County: 67.2 %Greenup County67.2Bullitt County: 66.6 %Bullitt County66.6Perry County: 66.4 %Perry County66.4Daviess County: 66.3 %Daviess County66.3Edmonson County: 65.6 %Edmonson County65.6Graves County: 65.3 %Graves County65.3Simpson County: 65.3 %Simpson County65.3Trigg County: 64.9 %Trigg County64.9McCracken County: 64.1 %McCracken County64.1Campbell County: 63.9 %Campbell County63.9McLean County: 62.4 %McLean County62.4Hancock County: 61.6 %Hancock County61.6Bell County: 60.4 %Bell County60.4Kenton County: 60.2 %Kenton County60.2Carter County: 59.7 %Carter County59.7Warren County: 59.1 %Warren County59.1Henderson County: 59 %Henderson County59Fayette County: 58.9 %Fayette County58.9Livingston County: 57.7 %Livingston County57.7Boyd County: 55.2 %Boyd County55.2Hardin County: 52.1 %Hardin County52.1Christian County: 44.5 %Christian County44.5Franklin County: 33.6 %Franklin County33.6Madison County: 30.2 %Madison County30.2Laurel County: 18 %Laurel County18Jefferson County: 13.4 %Jefferson County13.4
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2003 (%)Change on 2002
1Harlan County1000 pts
1Marshall County100+1.7 pts
3Scott County87.3+3.6 pts
4Morgan County79.4+4.7 pts
5Pulaski County78.1+3.8 pts
6Boone County76.4+8.6 pts
7Washington County76.1+5.1 pts
8Pike County73.4+11.9 pts
9Jessamine County72.1+3.7 pts
10Oldham County69+4.2 pts
11Greenup County67.2-2.5 pts
12Bullitt County66.6+8.4 pts
13Perry County66.4+8.1 pts
14Daviess County66.3+7.9 pts
15Edmonson County65.6-0.6 pts
16Graves County65.3-9 pts
16Simpson County65.3-6.1 pts
18Trigg County64.9-3.7 pts
19McCracken County64.1-2.8 pts
20Campbell County63.9+3.6 pts
21McLean County62.4-0.6 pts
22Hancock County61.6+4 pts
23Bell County60.4+8.5 pts
24Kenton County60.2+2.7 pts
25Carter County59.7+9.9 pts
26Warren County59.1+2.2 pts
27Henderson County59+5.3 pts
28Fayette County58.9+3.3 pts
29Livingston County57.7-4.5 pts
30Boyd County55.2+3.7 pts
31Hardin County52.1+2.8 pts
32Christian County44.5-3.5 pts
33Franklin County33.6+4.8 pts
34Madison County30.2+0.6 pts
35Laurel County18-7 pts
36Jefferson County13.4+4.6 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 2003 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), 2003) [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), 2003. 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=2003. 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), 2003. 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=2003.

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), 2003 [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=2003 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_kentucky_by_2003,
  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), 2003}},
  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=2003. 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), 2003
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=2003
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/kentucky-counties?period=2003.
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 100% in 2003, according to EPA.

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

Jefferson County, with 13.4% in 2003.

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 2003 and are not ranked.

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

Counties in Kentucky: more rankings