State air quality · 2025

Kentucky Air Quality Ranking

Across 25 monitored counties, the typical county in Kentucky posts a median AQI of 39 (Good) and 80.6% of monitored days were rated Good, from EPA AQS.

39
Avg median AQI
80.6%
Good-air days
25
Counties monitored
65%
Cleaner than US states

Kentucky's typical county median AQI is 39 (Good) across 25 monitored counties

According to the U.S. EPA Air Quality System, Kentucky monitors 25 counties with a day-weighted Good-day share of 80.6%. Cleanest: Greenup County (96.9% Good). Most polluted: Jefferson County (51.5%). These are annual summaries, not live AirNow readings.

Data source EPA Air Quality System (AQS)

Cleaner than US states
Kentucky's day-weighted Good-day share of 80.6% places it cleaner than 65% of US states.
In-state spread
Within Kentucky, Greenup County leads at 96.9% Good days while Jefferson County sits at 51.5% across 25 monitored counties.
2024→2025 release
Kentucky's Good-day share moved -0.1 points vs the 2024 EPA annual release.
Typical median AQI
Typical median AQI: 39

Verify with AirNow → · EPA AQS →

EPA state monitoring brief

AQS state key KENTUCKY

Kentucky · 2025 EPA AQS · 25 counties · med AQI 39 · 80.6% Good · Greenup→Jefferson spread

  • GOOD 39 Median AQI · Good
  • SHARE 80.6% Good-day share
  • COUNT 25 Counties monitored
  • UNH 2 Unhealthy+ days
  • RANK 65% Cleaner than states
  • O3 61.2% Main pollutant share

Good-day share peers

North Carolina81%South Dakota80.8%Kentucky (this)80.6%Tennessee80.3%
Good-day share neighbourhood · nearest ABS peers vs Kentucky

Kentucky's 80.6% Good-day share is cleaner than 65% of monitored US states; Greenup and Jefferson County bracket the in-state range. Open Greenup County →

According to EPA AQS annual summaries on PlainAirData, Kentucky ranks #18 of 52 by day-weighted good-day share (80.6%) and #27 by mean county median AQI (39.4). Hawaii is #1 of 52 by day-weighted good-day share (93.8% of monitored days) at mean county median-AQI #4 (27.3) ≠ Alaska #1 lowest mean county median AQI (20.3) at good-day share #8 (84.4%).

Data updated August 2026

What changed, what drives it, and how thick is the sample

Three derived views WPR-style word count does not substitute for: release-over-release movement from county annual rows, the EPA main-pollutant day mix, and how many counties sit below the 100-day ranking floor.

Release change

80.6%

Good-day share in 2025, down 0.1 percentage points vs 2024. County-mean median AQI 39, 1.8 points lower (cleaner) than 2024.

Pollutant mix

Ozone

Main driver on 61.2% of pollutant-assigned days.

  • Ozone 61.2%
  • PM2.5 38.5%
  • NO2 0.3%

Monitoring coverage

325

Average monitored days per county in the latest release. Every monitored county clears the 100-day ranking floor.

Counties Monitored

25

Good Days %

80.6%

Avg Median AQI

39

Total Unhealthy Days

2

Best Air Quality

Greenup County

Worst Air Quality

Jefferson County

Where Kentucky sits nationally

COUNT-derived placement among 52 US states with at least 365 monitored days in the latest county release. Kentucky's day-weighted Good-day share is 80.6% - cleaner than 65% of that comparison set.

Kentucky Good-day share vs. every US state

Day-weighted share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release

80.6% Cleaner than 65% higher than 65% of 52 US states

0.0%–5.0%: 0 US states (0%). Below this entry. 5.0%–10.0%: 0 US states (0%). Below this entry. 10.0%–15.0%: 0 US states (0%). Below this entry. 15.0%–20.0%: 0 US states (0%). Below this entry. 20.0%–25.0%: 0 US states (0%). Below this entry. 25.0%–30.0%: 0 US states (0%). Below this entry. 30.0%–35.0%: 0 US states (0%). Below this entry. 35.0%–40.0%: 0 US states (0%). Below this entry. 40.0%–45.0%: 0 US states (0%). Below this entry. 45.0%–50.0%: 0 US states (0%). Below this entry. 50.0%–55.0%: 0 US states (0%). Below this entry. 55.0%–60.0%: 0 US states (0%). Below this entry. 60.0%–65.0%: 2 US states (4%). Below this entry. 65.0%–70.0%: 9 US states (17%). Below this entry. 70.0%–75.0%: 11 US states (21%). Below this entry. 75.0%–80.0%: 11 US states (21%). Below this entry. 80.0%–85.0%: 13 US states (25%). This entry sits in this band. 85.0%–90.0%: 5 US states (10%). Above this entry. 90.0%–95.0%: 1 US states (2%). Above this entry. 95.0%–100.0%: 0 US states (0%). Above this entry. 100.0%–105.0%: 0 US states (0%). Above this entry. This state 0.0% 100% every floor-qualified US state, bucketed by value

Each bar is a band; taller bars hold more US states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.

Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2025

Which counties in Kentucky have the cleanest and most polluted air?

Cleanest counties in Kentucky

Share of monitored days rated Good (AQI 0–50)

  1. 1 Greenup County 96.9%
  2. 2 Morgan County 94.7%
  3. 3 Simpson County 93.4%
  4. 4 Edmonson County 92.1%
  5. 5 Washington County 90.3%
  6. 6 Carter County 89%
  7. 7 Livingston County 88.6%
  8. 8 Bullitt County 88.4%
  9. 9 Pike County 88.2%
  10. 10 Oldham County 87.7%
  11. 11 Boone County 87.6%
  12. 12 Perry County 87.1%

Good-day share · EPA Air Quality System

County Good % Median AQI
Greenup 96.9% 36
Morgan 94.7% 35
Simpson 93.4% 39
Edmonson 92.1% 36
Washington 90.3% 38
Carter 89.0% 36
Livingston 88.6% 40
Bullitt 88.4% 39
Pike 88.2% 34
Oldham 87.7% 39
Boone 87.6% 38
Perry 87.1% 36
Hancock 82.6% 43
Pulaski 81.4% 40
Boyd 80.0% 39
Jessamine 78.5% 41
Warren 77.8% 39
Campbell 75.6% 39
Fayette 75.0% 40
McCracken 74.5% 41
Hardin 73.4% 43
Christian 73.1% 41
Bell 67.0% 42
Daviess 61.9% 43
Jefferson 51.5% 49

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025. See our methodology for how AQI and median figures are computed.

Coverage: 25 counties in Kentucky with active monitoring stations. Unmonitored counties are not represented.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files, aggregated to the state level · 2020–2025

Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.

Informational only, not professional advice. Data from EPA AQS. See our disclaimer.