Median AQI
36
Good
Kentucky · County air quality · 2025
Carter County, Kentucky
Median AQI 36 (Good). 89.8% of monitored days rated Good, direct from EPA Air Quality System stations.
- 36
- Median AQI
- 89.8%
- Good-air days
- 0
- Unhealthy days
- 75%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Carter County's air is good on balance, cleaner than most US counties, a median AQI of 36 with 89.8% of 186 monitored days in the Good band, driven mainly by Ozone.
- 36
- median AQI · Good
- 89.8%
- 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 82.
Data updated July 2026
- Good · 167 d · 89.8%
- Moderate · 19 d · 10.2%
How did Carter County's air break down in 2025?
Across 186 monitored days, 167 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 82 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 186 days monitored. Median AQI: 36 (Good).
Insights: Carter County, Kentucky. EPA monitors recorded a median Air Quality Index of 36 across 186 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 167 (90%) fell in the Good band (AQI 0–50), 19 (10%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 51, while the worst single-day peak hit 82 (Moderate). Residents averaged about 26.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (91 days), PM2.5 (90 days), PM10 (5 days). Across the 2020–2025 trend window, good days shifted by -106 and the median AQI moved +3 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 82, 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); Christian (78.3% good, AQI 41).
Air Quality Summary
Good Days
89.8%
167 of 186 monitored days
14.8pp vs 75% target
Max AQI Recorded
82
Moderate
Health Grade
Good
90th-pct AQI 51
Carter County, Good days share 89.8%
National avg
Share of monitored days at AQI 0-50 (Good band).
Carter 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 186 monitored days across EPA AQI categories.
Good
167
90%
Moderate
19
10%
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 Carter County.
- Ozone · 91 days · 48.9%
- PM2.5 · 90 days · 48.4%
- PM10 · 5 days · 2.7%
Health Impact Assessment
Good
Carter County's air quality is rated Good based on 89.8% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 89.8% of monitored days in 2025, with a median AQI of 36. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 91 of 186 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Carter County. Best year: 2024 (321 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 273 | 12 | 0 | 0 | 33 | 64 |
| 2021 | 252 | 27 | 0 | 0 | 35 | 86 |
| 2022 | 293 | 68 | 0 | 0 | 39 | 71 |
| 2023 | 284 | 78 | 1 | 1 | 40 | 153 |
| 2024 | 321 | 39 | 0 | 0 | 37 | 62 |
| 2025 | 167 | 19 | 0 | 0 | 36 | 82 |
How does Carter County compare?
How Carter County compares
Good-day share better than US avg
Carter County 89.8%
Bell County, Kentucky 63.5%
US average 76.5%
Median AQI better than US avg
Carter County 36
Bell County, Kentucky 43
US average 38
Unhealthy days / yr about average
Carter 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 Carter County.
Aroostook County, Maine
AQI 36 · 84.1% good
Berkeley County, South Carolina
AQI 36 · 92.2% good
Claiborne County, Tennessee
AQI 36 · 96.3% good
Clark County, Illinois
AQI 36 · 92.1% good
Cobb County, Georgia
AQI 36 · 92.5% good
Fauquier County, Virginia
AQI 36 · 97.2% good
What Carter 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 36 means for exposure. Health guidance
- See how Carter County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Carter County with its Kentucky neighbours before drawing a conclusion about the region. All of Kentucky
Based on 186 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 Carter County, Kentucky? ▼
Carter County has a median Air Quality Index (AQI) of 36, rated "Good." 89.8% of monitored days (167 out of 186) had good air quality in 2025.
What is the main pollutant in Carter County? ▼
The primary pollutant in Carter County is Ozone (O3), which was the main AQI driver on 91 days (49% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Carter County have? ▼
In 2025, Carter County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 82.
Is the air quality in Carter County getting better or worse? ▼
Air quality in Carter County is worsening based on 5-year trends (2020-2025). Best year: 2024 with 321 good days. Worst year: 2025 with 167 good days.
What does AQI 36 mean for health? ▼
Carter County's median AQI of 36 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 Carter County compare to other counties in Kentucky? ▼
Carter County has 89.8% 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), Christian (78.3% good).
What is the 90th percentile AQI in Carter County? ▼
The 90th percentile AQI for Carter County is 51, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 82 (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.