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)

Floyd County had the highest share of days with good air quality (US EPA AQI) of 38 counties in 1999, at 100%. Jefferson County had the lowest, at 14.8%. The median was 53.1%. Source: EPA.

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Highest100Floyd County
Lowest14.8Jefferson County
Median53.138 counties

Map of counties, 1999

Bell County: 66.2 %Boone County: 57.5 %Boyd County: 52.6 %Bullitt County: 52.1 %Campbell County: 57.4 %Carter County: 35.3 %Christian County: 32.2 %Daviess County: 54.8 %Edmonson County: 50.6 %Fayette County: 50.7 %Floyd County: 100 %Franklin County: 23.6 %Graves County: 42.5 %Greenup County: 53.7 %Hancock County: 44.4 %Hardin County: 33.8 %Harlan County: 100 %Henderson County: 59.7 %Jefferson County: 14.8 %Jessamine County: 55.1 %Kenton County: 57.8 %Lawrence County: 100 %Livingston County: 40.2 %McCracken County: 53.4 %McLean County: 48.3 %Madison County: 27.1 %Marshall County: 90.4 %Morgan County: 53.7 %Oldham County: 29.1 %Perry County: 73.6 %Pike County: 33.1 %Pulaski County: 42.6 %Scott County: 52.8 %Simpson County: 61.9 %Trigg County: 55.8 %Warren County: 21.1 %Washington County: 56.5 %Whitley County: 98.2 %
  • Under 33
  • 33 to 46
  • 46 to 53
  • 53 to 56
  • 56 to 65
  • 65 and over
  • No data
%, 1999. 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, 1999

Floyd County: 100 %Floyd County100Harlan County: 100 %Harlan County100Lawrence County: 100 %Lawrence County100Whitley County: 98.2 %Whitley County98.2Marshall County: 90.4 %Marshall County90.4Perry County: 73.6 %Perry County73.6Bell County: 66.2 %Bell County66.2Simpson County: 61.9 %Simpson County61.9Henderson County: 59.7 %Henderson County59.7Kenton County: 57.8 %Kenton County57.8Boone County: 57.5 %Boone County57.5Campbell County: 57.4 %Campbell County57.4Washington County: 56.5 %Washington County56.5Trigg County: 55.8 %Trigg County55.8Jessamine County: 55.1 %Jessamine County55.1Daviess County: 54.8 %Daviess County54.8Greenup County: 53.7 %Greenup County53.7Morgan County: 53.7 %Morgan County53.7McCracken County: 53.4 %McCracken County53.4Scott County: 52.8 %Scott County52.8Boyd County: 52.6 %Boyd County52.6Bullitt County: 52.1 %Bullitt County52.1Fayette County: 50.7 %Fayette County50.7Edmonson County: 50.6 %Edmonson County50.6McLean County: 48.3 %McLean County48.3Hancock County: 44.4 %Hancock County44.4Pulaski County: 42.6 %Pulaski County42.6Graves County: 42.5 %Graves County42.5Livingston County: 40.2 %Livingston County40.2Carter County: 35.3 %Carter County35.3Hardin County: 33.8 %Hardin County33.8Pike County: 33.1 %Pike County33.1Christian County: 32.2 %Christian County32.2Oldham County: 29.1 %Oldham County29.1Madison County: 27.1 %Madison County27.1Franklin County: 23.6 %Franklin County23.6Warren County: 21.1 %Warren County21.1Jefferson County: 14.8 %Jefferson County14.8Floyd County: 100 %Floyd County100Harlan County: 100 %Harlan County100Lawrence County: 100 %Lawrence County100Whitley County: 98.2 %Whitley County98.2Marshall County: 90.4 %Marshall County90.4Perry County: 73.6 %Perry County73.6Bell County: 66.2 %Bell County66.2Simpson County: 61.9 %Simpson County61.9Henderson County: 59.7 %Henderson County59.7Kenton County: 57.8 %Kenton County57.8Boone County: 57.5 %Boone County57.5Campbell County: 57.4 %Campbell County57.4Washington County: 56.5 %Washington County56.5Trigg County: 55.8 %Trigg County55.8Jessamine County: 55.1 %Jessamine County55.1Daviess County: 54.8 %Daviess County54.8Greenup County: 53.7 %Greenup County53.7Morgan County: 53.7 %Morgan County53.7McCracken County: 53.4 %McCracken County53.4Scott County: 52.8 %Scott County52.8Boyd County: 52.6 %Boyd County52.6Bullitt County: 52.1 %Bullitt County52.1Fayette County: 50.7 %Fayette County50.7Edmonson County: 50.6 %Edmonson County50.6McLean County: 48.3 %McLean County48.3Hancock County: 44.4 %Hancock County44.4Pulaski County: 42.6 %Pulaski County42.6Graves County: 42.5 %Graves County42.5Livingston County: 40.2 %Livingston County40.2Carter County: 35.3 %Carter County35.3Hardin County: 33.8 %Hardin County33.8Pike County: 33.1 %Pike County33.1Christian County: 32.2 %Christian County32.2Oldham County: 29.1 %Oldham County29.1Madison County: 27.1 %Madison County27.1Franklin County: 23.6 %Franklin County23.6Warren County: 21.1 %Warren County21.1Jefferson County: 14.8 %Jefferson County14.8
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties1999 (%)Change on 1998
1Floyd County1000 pts
1Harlan County1000 pts
1Lawrence County100+20.8 pts
4Whitley County98.2-1.8 pts
5Marshall County90.4-2.5 pts
6Perry County73.6-12.2 pts
7Bell County66.2-8.9 pts
8Simpson County61.9-6.3 pts
9Henderson County59.7-11.6 pts
10Kenton County57.8-13.2 pts
11Boone County57.5-4.2 pts
12Campbell County57.4-16.3 pts
13Washington County56.5-4.6 pts
14Trigg County55.8-3.6 pts
15Jessamine County55.1-4.5 pts
16Daviess County54.8-16.7 pts
17Greenup County53.7+4.7 pts
17Morgan County53.7-9 pts
19McCracken County53.4-12.4 pts
20Scott County52.8-17.6 pts
21Boyd County52.6-27.7 pts
22Bullitt County52.1-15.3 pts
23Fayette County50.7-23 pts
24Edmonson County50.6-2.2 pts
25McLean County48.3+0.2 pts
26Hancock County44.4+7.5 pts
27Pulaski County42.6-12.3 pts
28Graves County42.5-4.6 pts
29Livingston County40.2-4.8 pts
30Carter County35.3-5.1 pts
31Hardin County33.8-35.1 pts
32Pike County33.1-29.3 pts
33Christian County32.2-10.3 pts
34Oldham County29.1-26.3 pts
35Madison County27.1-71.1 pts
36Franklin County23.6n/a
37Warren County21.1-78.9 pts
38Jefferson County14.8-46 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. 17 counties with data in other periods have no value for 1999 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), 1999) [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), 1999. 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=1999. 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), 1999. 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=1999.

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), 1999 [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=1999 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_kentucky_by_1999,
  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), 1999}},
  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=1999. 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), 1999
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=1999
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/kentucky-counties?period=1999.
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)?

Floyd County, with 100% in 1999, according to EPA.

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

Jefferson County, with 14.8% in 1999.

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. 17 counties have no value for 1999 and are not ranked.

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

Counties in Kentucky: more rankings