Metro area air quality · 2025
Louisville/Jefferson County, KY-IN
Median AQI 52 (Moderate). 44.1% of monitored days rated Good across this metro's EPA monitoring network.
- 52
- Median AQI
- 44.1%
- Good-air days
- 1
- Unhealthy days
- 9%
- Cleaner than US metros
Louisville/Jefferson County, KY-IN posted a 2025 median AQI of 52 (Moderate) with 44.1% Good days
According to the U.S. EPA Air Quality System, the Louisville/Jefferson County, KY-IN CBSA recorded a median AQI of 52 across 365 monitored days in 2025, with 44.1% rated Good and 1 unhealthy or worse. This is an annual metro comparison, not a live advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US metros
- The Louisville/Jefferson County, KY-IN CBSA's 44.1% Good-day share places it cleaner than 9% of US metros in 2025.
- Closest median-AQI peer
- Augusta-Richmond County, GA-SC (46.0% Good, median AQI 52) is the closest nationwide median-AQI peer to Louisville/Jefferson County, KY-IN.
- 2020–2025 Good-day shift
- Louisville/Jefferson County, KY-IN's Good-day share moved +5.1 points from 2020 to 2025 (median AQI -1).
- Median AQI
- Median AQI: 52
Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →
The verdict
Louisville/Jefferson County, KY-IN lands in the lower Good-day tercile (44.1% Good), a thinner clean-air share than most CBSA peers here. On the EPA scale the metro runs moderate, among the more polluted US metros, with a median AQI of 52 and 44.1% of 365 monitored days in the Good band.
- 52
- median AQI · Moderate
- 44.1%
- days rated Good
- 9%
- cleaner than US metros
- 153
- worst single reading
1 day reached Unhealthy or worse across the metro's monitors in 2025.
Annual release change
What changed in the 2025 EPA annual release
- Louisville/Jefferson County, KY-IN metro's Good-day share fell from 48.9% to 45.2% between the 2024 and 2025 EPA annual releases, a change of -3.6 percentage points.
Louisville/Jefferson County, KY-IN lands in the lower Good-day tercile (44.1% Good), a thinner clean-air share than most CBSA peers here. Signature read: 44.1% Good-day share (low tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 52 over 365 measured days in 2025 (Moderate / Poor). The monitored-day split lands at 161 Good (44%), 194 Moderate (53%), and 9 Unhealthy-for-Sensitive-Groups (2%). The 90th-percentile AQI finished at 71; the highest single-day reading hit 153 (Unhealthy).
Across 2020–2025, Good-day share shifted +5.1 points and median AQI moved -1 (improving). The annual record contains 1 day at Unhealthy or worse. Metros with comparable AQI profiles include Augusta-Richmond County, GA-SC (46.0% good, AQI 52); Beaumont-Port Arthur, TX (41.4% good, AQI 52); Birmingham-Hoover, AL (43.0% good, AQI 52).
Air Quality Summary
Median AQI
52
Moderate
Good Days
44.1%
161 of 365 days
Max AQI
153
Unhealthy
Health Grade
Poor
90th pct: 71
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
161
44%
Moderate
194
53%
USG
9
2%
Unhealthy
1
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The Louisville/Jefferson County, KY-IN metro area's air quality is rated Poor based on 44.1% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 9 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 153. Sensitive groups should monitor real-time conditions at AirNow.gov.
How does the Louisville/Jefferson County, KY-IN metro compare?
How Louisville/Jefferson County, KY-IN compares
5-Year Air Quality Trend
Air quality is improving in the Louisville/Jefferson County, KY-IN metro. Highest Good-day share: 2024 (48.9%, 173 of 354 monitored days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 144 | 215 | 0 | 53 | 143 |
| 2021 | 133 | 225 | 0 | 54 | 143 |
| 2022 | 136 | 221 | 0 | 54 | 136 |
| 2023 | 117 | 227 | 1 | 55 | 182 |
| 2024 | 173 | 180 | 1 | 51 | 156 |
| 2025 | 161 | 194 | 1 | 52 | 153 |
Metros with a similar median AQI
CBSA peers nationwide whose annual median AQI sits near Louisville/Jefferson County, KY-IN (52).
Augusta-Richmond County, GA-SC
Median AQI 52 · 46.0% Good-day share
Beaumont-Port Arthur, TX
Median AQI 52 · 41.4% Good-day share
Birmingham-Hoover, AL
Median AQI 52 · 43.0% Good-day share
Charlotte-Concord-Gastonia, NC-SC
Median AQI 52 · 46.0% Good-day share
El Dorado, AR
Median AQI 52 · 41.8% Good-day share
Grand Rapids-Wyoming, MI
Median AQI 52 · 41.9% Good-day share
Metros with similar unhealthy-day exposure
A second relationship type: metros whose unhealthy-or-worse day count is closest to Louisville/Jefferson County, KY-IN's 1 (independent of median AQI).
Ann Arbor, MI
1 unhealthy-or-worse days · median AQI 41
Bangor, ME
1 unhealthy-or-worse days · median AQI 33
Baraboo, WI
1 unhealthy-or-worse days · median AQI 35
Bartlesville, OK
1 unhealthy-or-worse days · median AQI 44
Beaver Dam, WI
1 unhealthy-or-worse days · median AQI 40
Bellingham, WA
1 unhealthy-or-worse days · median AQI 31
Frequently Asked Questions
How many unhealthy air days does Louisville/Jefferson County, KY-IN have? ▼
What is the air quality in the Louisville/Jefferson County, KY-IN metro area? ▼
Is air quality in Louisville/Jefferson County, KY-IN getting better or worse? ▼
What does AQI 52 mean for health? ▼
How does Louisville/Jefferson County, KY-IN compare to other metro areas? ▼
What is the 90th percentile AQI for Louisville/Jefferson County, KY-IN? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Louisville/Jefferson County, KY-IN, 2025. See our methodology for how AQI, median, and coverage figures are computed.
Read our methodology , how this data is sourced, computed, and verified.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary, Louisville/Jefferson County, KY-IN · 2020–2025