Counties in Kentucky by share of days unhealthy for sensitive groups or worse (US EPA AQI)

McLean County had the highest share of days unhealthy for sensitive groups or worse (US EPA AQI) of 37 counties in 1994, at 20.1%. Whitley County had the lowest, at 0%. The median was 5.5%. Source: EPA.

Highest20.1McLean County

Lowest0Whitley County

Median5.537 counties

Map of counties, 1994

Under 3.6
3.6 to 5.5
5.5 to 8.2
8.2 to 13
13 and over
No data

%, 1994. 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, 1994

%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

Rank	Counties	1994 (%)	Change on 1993
1	McLean County	20.1	+13 pts
2	Scott County	16.4	+11.4 pts
3	Oldham County	16.1	+8.6 pts
4	Christian County	15.6	+10.4 pts
5	Hardin County	14.8	+7.4 pts
6	Boone County	14.6	+7.5 pts
7	Jefferson County	13.4	+5.5 pts
8	Hancock County	13.1	+4.7 pts
9	Greenup County	10.2	-0.1 pts
10	Livingston County	9.9	+2.1 pts
11	Washington County	9.7	+2.4 pts
12	Trigg County	8.5	+8.5 pts
13	Daviess County	8.2	+1.6 pts
13	Jessamine County	8.2	+3.5 pts
13	Kenton County	8.2	+4.6 pts
16	Morgan County	6.7	+5.1 pts
17	Fayette County	6.6	+0.3 pts
18	Lawrence County	5.6	+1.8 pts
19	Boyd County	5.5	+0.6 pts
20	Bullitt County	5	+0.7 pts
20	Campbell County	5	-0.2 pts
22	Henderson County	4.9	+1.1 pts
23	Pike County	3.9	+0.9 pts
24	Pulaski County	3.8	-0.8 pts
25	McCracken County	3.6	+2.8 pts
26	Edmonson County	3.5	+2.3 pts
26	Simpson County	3.5	+1.6 pts
28	Perry County	2.6	+0.9 pts
29	Graves County	2.1	-0.2 pts
30	Bell County	1.4	-0.5 pts
31	Carter County	0	0 pts
31	Floyd County	0	0 pts
31	Harlan County	0	0 pts
31	Madison County	0	0 pts
31	Marshall County	0	0 pts
31	Warren County	0	0 pts
31	Whitley County	0	0 pts

Other periods

About this ranking

Days with a daily Air Quality Index above 100 (unhealthy for sensitive groups, unhealthy, very unhealthy or hazardous) 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; the counts are stored with each value.

Use the share rather than the number of days to compare counties, since the days with an AQI differ. 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 1994 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: days with an AQI above 100 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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts (Counties in Kentucky by share of days unhealthy for sensitive groups or worse (US EPA AQI), 1994) [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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts, Counties in Kentucky by share of days unhealthy for sensitive groups or worse (US EPA AQI), 1994. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/kentucky-counties?period=1994. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts. Counties in Kentucky by share of days unhealthy for sensitive groups or worse (US EPA AQI), 1994. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/kentucky-counties?period=1994.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts, Counties in Kentucky by share of days unhealthy for sensitive groups or worse (US EPA AQI), 1994 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/unhealthy-air-quality-days-share/kentucky-counties?period=1994 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_kentucky_by_1994,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts: Counties in Kentucky by share of days unhealthy for sensitive groups or worse (US EPA AQI), 1994}},
  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/unhealthy-air-quality-days-share/kentucky-counties?period=1994. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: days with an AQI above 100 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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts: Counties in Kentucky by share of days unhealthy for sensitive groups or worse (US EPA AQI), 1994
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/unhealthy-air-quality-days-share/kentucky-counties?period=1994
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/kentucky-counties?period=1994.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: days with an AQI above 100 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 unhealthy for sensitive groups or worse (US EPA AQI)?

McLean County, with 20.1% in 1994, according to EPA.

Which county has the lowest share of days unhealthy for sensitive groups or worse (US EPA AQI)?

Whitley County, with 0% in 1994.

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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 18 counties have no value for 1994 and are not ranked.