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)

Marshall County had the highest share of days with good air quality (US EPA AQI) of 37 counties in 2001, at 100%. Jefferson County had the lowest, at 13.7%. The median was 61%. Source: EPA.

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Highest100Marshall County
Lowest13.7Jefferson County
Median6137 counties

Map of counties, 2001

Bell County: 61.9 %Boone County: 72.1 %Boyd County: 54.5 %Bullitt County: 51.7 %Campbell County: 60.7 %Carter County: 50.7 %Christian County: 44.1 %Daviess County: 62.9 %Edmonson County: 63.1 %Fayette County: 53.4 %Franklin County: 30.8 %Graves County: 77.9 %Greenup County: 57.6 %Hancock County: 60.4 %Hardin County: 45.4 %Harlan County: 98.4 %Henderson County: 62.5 %Jefferson County: 13.7 %Jessamine County: 73.4 %Kenton County: 61 %Livingston County: 55.5 %McCracken County: 57 %McLean County: 61.2 %Madison County: 30.1 %Marshall County: 100 %Morgan County: 68.4 %Muhlenberg County: 56.3 %Oldham County: 59.9 %Perry County: 62.3 %Pike County: 59.4 %Pulaski County: 68.7 %Scott County: 89.8 %Simpson County: 64.5 %Trigg County: 63.3 %Warren County: 56.4 %Washington County: 67.3 %Whitley County: 100 %
  • Under 52
  • 52 to 57
  • 57 to 61
  • 61 to 63
  • 63 to 72
  • 72 and over
  • No data
%, 2001. 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, 2001

Marshall County: 100 %Marshall County100Whitley County: 100 %Whitley County100Harlan County: 98.4 %Harlan County98.4Scott County: 89.8 %Scott County89.8Graves County: 77.9 %Graves County77.9Jessamine County: 73.4 %Jessamine County73.4Boone County: 72.1 %Boone County72.1Pulaski County: 68.7 %Pulaski County68.7Morgan County: 68.4 %Morgan County68.4Washington County: 67.3 %Washington County67.3Simpson County: 64.5 %Simpson County64.5Trigg County: 63.3 %Trigg County63.3Edmonson County: 63.1 %Edmonson County63.1Daviess County: 62.9 %Daviess County62.9Henderson County: 62.5 %Henderson County62.5Perry County: 62.3 %Perry County62.3Bell County: 61.9 %Bell County61.9McLean County: 61.2 %McLean County61.2Kenton County: 61 %Kenton County61Campbell County: 60.7 %Campbell County60.7Hancock County: 60.4 %Hancock County60.4Oldham County: 59.9 %Oldham County59.9Pike County: 59.4 %Pike County59.4Greenup County: 57.6 %Greenup County57.6McCracken County: 57 %McCracken County57Warren County: 56.4 %Warren County56.4Muhlenberg County: 56.3 %Muhlenberg County56.3Livingston County: 55.5 %Livingston County55.5Boyd County: 54.5 %Boyd County54.5Fayette County: 53.4 %Fayette County53.4Bullitt County: 51.7 %Bullitt County51.7Carter County: 50.7 %Carter County50.7Hardin County: 45.4 %Hardin County45.4Christian County: 44.1 %Christian County44.1Franklin County: 30.8 %Franklin County30.8Madison County: 30.1 %Madison County30.1Jefferson County: 13.7 %Jefferson County13.7Marshall County: 100 %Marshall County100Whitley County: 100 %Whitley County100Harlan County: 98.4 %Harlan County98.4Scott County: 89.8 %Scott County89.8Graves County: 77.9 %Graves County77.9Jessamine County: 73.4 %Jessamine County73.4Boone County: 72.1 %Boone County72.1Pulaski County: 68.7 %Pulaski County68.7Morgan County: 68.4 %Morgan County68.4Washington County: 67.3 %Washington County67.3Simpson County: 64.5 %Simpson County64.5Trigg County: 63.3 %Trigg County63.3Edmonson County: 63.1 %Edmonson County63.1Daviess County: 62.9 %Daviess County62.9Henderson County: 62.5 %Henderson County62.5Perry County: 62.3 %Perry County62.3Bell County: 61.9 %Bell County61.9McLean County: 61.2 %McLean County61.2Kenton County: 61 %Kenton County61Campbell County: 60.7 %Campbell County60.7Hancock County: 60.4 %Hancock County60.4Oldham County: 59.9 %Oldham County59.9Pike County: 59.4 %Pike County59.4Greenup County: 57.6 %Greenup County57.6McCracken County: 57 %McCracken County57Warren County: 56.4 %Warren County56.4Muhlenberg County: 56.3 %Muhlenberg County56.3Livingston County: 55.5 %Livingston County55.5Boyd County: 54.5 %Boyd County54.5Fayette County: 53.4 %Fayette County53.4Bullitt County: 51.7 %Bullitt County51.7Carter County: 50.7 %Carter County50.7Hardin County: 45.4 %Hardin County45.4Christian County: 44.1 %Christian County44.1Franklin County: 30.8 %Franklin County30.8Madison County: 30.1 %Madison County30.1Jefferson County: 13.7 %Jefferson County13.7
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2001 (%)Change on 2000
1Marshall County100+4.9 pts
1Whitley County100+5.1 pts
3Harlan County98.4+0.1 pts
4Scott County89.8+5.7 pts
5Graves County77.9+17.4 pts
6Jessamine County73.4+5.9 pts
7Boone County72.1-5.5 pts
8Pulaski County68.7+12 pts
9Morgan County68.4+1.3 pts
10Washington County67.3+5 pts
11Simpson County64.5-1.5 pts
12Trigg County63.3-1.9 pts
13Edmonson County63.1+4.4 pts
14Daviess County62.9-5 pts
15Henderson County62.5+6.5 pts
16Perry County62.3-8.8 pts
17Bell County61.9-0.9 pts
18McLean County61.2-6.2 pts
19Kenton County61+2.5 pts
20Campbell County60.7+3.2 pts
21Hancock County60.4-6.8 pts
22Oldham County59.9-8.4 pts
23Pike County59.4+3.8 pts
24Greenup County57.6-6.7 pts
25McCracken County57+1.5 pts
26Warren County56.4+5.6 pts
27Muhlenberg County56.3n/a
28Livingston County55.5+3.3 pts
29Boyd County54.5-0.1 pts
30Fayette County53.4-4.5 pts
31Bullitt County51.7-6.9 pts
32Carter County50.7+2.5 pts
33Hardin County45.4-5.4 pts
34Christian County44.1+6 pts
35Franklin County30.8+11.7 pts
36Madison County30.1+11.8 pts
37Jefferson County13.7+3 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. 18 counties with data in other periods have no value for 2001 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), 2001) [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), 2001. 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=2001. 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), 2001. 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=2001.

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), 2001 [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=2001 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_kentucky_by_2001,
  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), 2001}},
  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=2001. 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), 2001
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=2001
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/kentucky-counties?period=2001.
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)?

Marshall County, with 100% in 2001, according to EPA.

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

Jefferson County, with 13.7% in 2001.

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. 18 counties have no value for 2001 and are not ranked.

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

Counties in Kentucky: more rankings