Median AQI
37
Good
Kentucky · County air quality · 2025
Warren County, Kentucky
Median AQI 37 (Good). 81.2% of monitored days rated Good, direct from EPA Air Quality System stations.
- 37
- Median AQI
- 81.2%
- Good-air days
- 0
- Unhealthy days
- 56%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Warren County's air is good on balance, cleaner than the median US county, a median AQI of 37 with 81.2% of 181 monitored days in the Good band, driven mainly by PM2.5.
- 37
- median AQI · Good
- 81.2%
- days rated Good
- PM2.5
- main pollutant
- 56%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 73.
Data updated July 2026
- Good · 147 d · 81.2%
- Moderate · 34 d · 18.8%
How did Warren County's air break down in 2025?
Across 181 monitored days, 147 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 73 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 181 days monitored. Median AQI: 37 (Good).
Insights: Warren County, Kentucky. EPA monitors recorded a median Air Quality Index of 37 across 181 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 147 (81%) fell in the Good band (AQI 0–50), 34 (19%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 53, while the worst single-day peak hit 73 (Moderate). Residents averaged about 24.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (103 days), Ozone (78 days). Across the 2020–2025 trend window, good days shifted by -90 and the median AQI moved -7 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 73, moderate but never Unhealthy. Nearby counties show comparable readings: Bell (63.5% good, AQI 43); Boone (95.1% good, AQI 38); Boyd (82.8% good, AQI 39); Bullitt (92.7% good, AQI 39); Campbell (78.5% good, AQI 39); Carter (89.8% good, AQI 36).
Air Quality Summary
Good Days
81.2%
147 of 181 monitored days
6.2pp vs 75% target
Max AQI Recorded
73
Moderate
Health Grade
Good
90th-pct AQI 53
Warren County, Good days share 81.2%
National avg
Share of monitored days at AQI 0-50 (Good band).
Warren County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 181 monitored days across EPA AQI categories.
Good
147
81%
Moderate
34
19%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Warren County.
- PM2.5 · 103 days · 56.9%
- Ozone · 78 days · 43.1%
Health Impact Assessment
Good
Warren County's air quality is rated Good based on 81.2% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 81.2% of monitored days in 2025, with a median AQI of 37. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 103 of 181 monitored days.
5-Year Air Quality Trend
Air quality is improving in Warren County. Best year: 2024 (290 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 237 | 129 | 0 | 0 | 44 | 97 |
| 2021 | 218 | 143 | 2 | 0 | 45 | 117 |
| 2022 | 248 | 115 | 0 | 0 | 43 | 84 |
| 2023 | 238 | 124 | 2 | 1 | 44 | 155 |
| 2024 | 290 | 74 | 0 | 0 | 39 | 87 |
| 2025 | 147 | 34 | 0 | 0 | 37 | 73 |
How does Warren County compare?
How Warren County compares
Good-day share better than US avg
Warren County 81.2%
Bell County, Kentucky 63.5%
US average 76.5%
Median AQI better than US avg
Warren County 37
Bell County, Kentucky 43
US average 38
Unhealthy days / yr about average
Warren County 0
Bell County, Kentucky 0
US average 0
Other Counties in Kentucky
Air quality comparison for nearby counties in Kentucky.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Warren County.
Alachua County, Florida
AQI 37 · 90.1% good
Beltrami County, Minnesota
AQI 37 · 88.8% good
Benewah County, Idaho
AQI 37 · 74.6% good
Brevard County, Florida
AQI 37 · 89.7% good
Brown County, Indiana
AQI 37 · 94.5% good
Brown County, Wisconsin
AQI 37 · 79.0% good
What Warren County's air means for you
The air here stays in the breathable range year-round, with PM2.5 the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 37 means for exposure. Health guidance
- See how Warren County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Warren County with its Kentucky neighbours before drawing a conclusion about the region. All of Kentucky
Based on 181 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Warren County, Kentucky? ▼
Warren County has a median Air Quality Index (AQI) of 37, rated "Good." 81.2% of monitored days (147 out of 181) had good air quality in 2025.
What is the main pollutant in Warren County? ▼
The primary pollutant in Warren County is Fine Particles (PM2.5), which was the main AQI driver on 103 days (57% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Warren County have? ▼
In 2025, Warren County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 73.
Is the air quality in Warren County getting better or worse? ▼
Air quality in Warren County is improving based on 5-year trends (2020-2025). Best year: 2024 with 290 good days. Worst year: 2025 with 147 good days.
What does AQI 37 mean for health? ▼
Warren County's median AQI of 37 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Warren County compare to other counties in Kentucky? ▼
Warren County has 81.2% good air days. Nearby counties in Kentucky: Bell (63.5% good), Boone (95.1% good), Boyd (82.8% good), Bullitt (92.7% good), Campbell (78.5% good), Carter (89.8% good).
What is the 90th percentile AQI in Warren County? ▼
The 90th percentile AQI for Warren County is 53, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 73 (Moderate).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer.
Every figure on PlainAir 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.