Median AQI
38
Good
Kentucky · County air quality · 2025
Boone County, Kentucky
Median AQI 38 (Good). 87.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 38
- Median AQI
- 87.6%
- Good-air days
- 0
- Unhealthy days
- 75%
- Cleaner than US counties
Boone County's 2025 annual median AQI is 38 (Good), with 87.6% Good days
According to the U.S. EPA Air Quality System, Boone County, Kentucky posted a 2025 median AQI of 38 (Good) across 242 monitored days, with 87.6% rated Good and 0 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Boone County's 87.6% Good-day share places it cleaner than 75% of US counties in 2025.
- Closest median-AQI peer
- Adams County (94.7% Good, median AQI 38) is the closest nationwide median-AQI peer to Boone County.
- 2020–2025 trend
- Boone County's floor-qualifying Good-day share is stable from 2020 to 2025 (90.1% → 87.6%).
- Median AQI
- Median AQI: 38
The verdict
According to EPA Air Quality System monitoring data, Boone County's air is good on balance, cleaner than most US counties, a median AQI of 38 with 87.6% of 242 monitored days in the Good band, driven mainly by Ozone.
- 38
- median AQI · Good
- 87.6%
- days rated Good
- Ozone
- main pollutant
- 75%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 108.
Annual release change
What changed in the 2025 EPA annual release
- Boone County's Good-day share rose from 79.6% to 87.6% between the 2024 and 2025 EPA annual releases, a change of +8.0 percentage points.
- Boone County's peak single-day AQI fell from 129 to 108 between the 2024 and 2025 EPA annual releases, a change of -21 points.
- Boone County's median AQI fell from 43 to 38 between the 2024 and 2025 EPA annual releases, a change of -5 points.
Data updated August 2026
- Good · 212 d · 87.6%
- Moderate · 27 d · 11.2%
- USG · 3 d · 1.2%
How did Boone County's air break down in 2025?
Across 242 monitored days, 212 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 108 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 242 days monitored. Median AQI: 38 (Good).
Insights: Boone County, Kentucky. EPA monitors recorded a median Air Quality Index of 38 across 242 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 212 (88%) fell in the Good band (AQI 0–50), 27 (11%) registered Moderate readings, and 3 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 54, while the worst single-day peak hit 108 (USG). Residents averaged about 26.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (242 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -2.5 points and the median AQI moved +2 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 108, usg but never Unhealthy. Nearby counties show comparable readings: Bell (67.0% good, AQI 42); Boyd (80.0% good, AQI 39); Bullitt (88.4% good, AQI 39); Campbell (75.6% good, AQI 39); Carter (89.0% good, AQI 36); Christian (73.1% good, AQI 41).
Air Quality Summary
Good Days
87.6%
212 of 242 monitored days
12.6pp vs 75% target
Max AQI Recorded
108
USG
Health Grade
Good
90th-pct AQI 54
Boone County, Good days share 87.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
Boone 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 242 monitored days across EPA AQI categories.
Good
212
88%
Moderate
27
11%
USG
3
1%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Boone County.
- Ozone · 242 days · 100.0%
Health Impact Assessment
Good
Boone County's air quality is rated Good based on 87.6% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 87.6% of monitored days in 2025, with a median AQI of 38. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 242 of 242 monitored days.
5-Year Air Quality Trend
Air quality is stable in Boone County. Highest Good-day share: 2021 (92.2%, 225 of 244 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 218 | 24 | 0 | 0 | 36 | 87 |
| 2021 | 225 | 19 | 0 | 0 | 39 | 90 |
| 2022 | 173 | 26 | 0 | 0 | 41 | 97 |
| 2023 | 187 | 51 | 6 | 1 | 44 | 156 |
| 2024 | 183 | 46 | 1 | 0 | 43 | 129 |
| 2025 | 212 | 27 | 3 | 0 | 38 | 108 |
How does Boone County compare?
How Boone County compares
Good-day share better than US avg
Boone County 87.6%
Adams County, Illinois 94.7%
US average 76.0%
Median AQI better than US avg
Boone County 38
Adams County, Illinois 38
US average 39
Unhealthy days / yr better than US avg
Boone County 0
Adams County, Illinois 0
US average 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Boone County (38), not geographic neighbors.
Adams County, Illinois
Median AQI 38 · 94.7% Good-day share
Albemarle County, Virginia
Median AQI 38 · 81.0% Good-day share
Alexander County, North Carolina
Median AQI 38 · 93.5% Good-day share
Amador County, California
Median AQI 38 · 87.4% Good-day share
Anoka County, Minnesota
Median AQI 38 · 74.1% Good-day share
Avery County, North Carolina
Median AQI 38 · 92.3% Good-day share
Same primary pollutant: Ozone
Ozone led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
Anne Arundel County, Maryland
87.6% Good-day share · median AQI 40
Chittenden County, Vermont
87.7% Good-day share · median AQI 38
El Dorado County, California
87.7% Good-day share · median AQI 40
Santa Cruz County, California
87.7% Good-day share · median AQI 35
Oldham County, Kentucky
87.7% Good-day share · median AQI 39
Clay County, South Dakota
87.8% Good-day share · median AQI 34
Kentucky counties on the map
Geographic containment only, other monitored counties in Kentucky, independent of AQI or pollutant match.
What Boone County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 38 means for exposure. Health guidance
- See how Boone County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Boone County with its Kentucky neighbours before drawing a conclusion about the region. All of Kentucky
Based on 242 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Boone County, Kentucky? ▼
Boone County has a median Air Quality Index (AQI) of 38, rated "Good." 87.6% of monitored days (212 out of 242) had good air quality in 2025.
What is the main pollutant in Boone County? ▼
The primary pollutant in Boone County is Ozone (O3), which was the main AQI driver on 242 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Boone County have? ▼
In 2025, Boone County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 108.
Is the air quality in Boone County getting better or worse? ▼
Air quality in Boone County is stable across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2021 at 92.2% (225 of 244 days). Lowest qualifying Good-day share: 2023 at 76.3% (187 of 245 days).
What does AQI 38 mean for health? ▼
Boone County's median AQI of 38 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Boone County compare to other counties in Kentucky? ▼
Boone County has 87.6% good air days. Nearby counties in Kentucky: Bell (67.0% good), Boyd (80.0% good), Bullitt (88.4% good), Campbell (75.6% good), Carter (89.0% good), Christian (73.1% good).
What is the 90th percentile AQI in Boone County? ▼
The 90th percentile AQI for Boone County is 54, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 108 (USG).
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. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Boone County, Kentucky · 2020–2025
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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.