Median AQI
43
Good
Missouri · County air quality · 2025
Clinton County, Missouri
Median AQI 43 (Good). 84.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 43
- Median AQI
- 84.6%
- Good-air days
- 0
- Unhealthy days
- 65%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Clinton County's air is good on balance, cleaner than the median US county, a median AQI of 43 with 84.6% of 91 monitored days in the Good band, driven mainly by Ozone.
- 43
- median AQI · Good
- 84.6%
- days rated Good
- Ozone
- main pollutant
- 65%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 74.
Data updated July 2026
- Good · 77 d · 84.6%
- Moderate · 14 d · 15.4%
How did Clinton County's air break down in 2025?
Across 91 monitored days, 77 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 74 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 91 days monitored. Median AQI: 43 (Good).
Insights: Clinton County, Missouri. EPA monitors recorded a median Air Quality Index of 43 across 91 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 77 (85%) fell in the Good band (AQI 0–50), 14 (15%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 74 (Moderate). Residents averaged about 25.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (91 days). Across the 2020–2025 trend window, good days shifted by -149 and the median AQI moved +6 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 74, moderate but never Unhealthy. Nearby counties show comparable readings: Andrew (84.3% good, AQI 42); Boone (89.1% good, AQI 41); Buchanan (64.2% good, AQI 39); Callaway (85.6% good, AQI 42); Cass (82.2% good, AQI 41); Cedar (81.8% good, AQI 40).
Air Quality Summary
Good Days
84.6%
77 of 91 monitored days
9.6pp vs 75% target
Max AQI Recorded
74
Moderate
Health Grade
Good
90th-pct AQI 61
Clinton County, Good days share 84.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
Clinton 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 91 monitored days across EPA AQI categories.
Good
77
85%
Moderate
14
15%
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 Clinton County.
- Ozone · 91 days · 100.0%
Health Impact Assessment
Good
Clinton County's air quality is rated Good based on 84.6% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 84.6% of monitored days in 2025, with a median AQI of 43. 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 91 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Clinton County. Best year: 2020 (226 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 226 | 19 | 0 | 0 | 37 | 87 |
| 2021 | 221 | 24 | 0 | 0 | 38 | 97 |
| 2022 | 211 | 33 | 1 | 0 | 41 | 101 |
| 2023 | 168 | 66 | 11 | 0 | 44 | 133 |
| 2024 | 219 | 37 | 1 | 0 | 41 | 101 |
| 2025 | 77 | 14 | 0 | 0 | 43 | 74 |
How does Clinton County compare?
How Clinton County compares
Good-day share better than US avg
Clinton County 84.6%
Andrew County, Missouri 84.3%
US average 76.5%
Median AQI worse than US avg
Clinton County 43
Andrew County, Missouri 42
US average 38
Unhealthy days / yr about average
Clinton County 0
Andrew County, Missouri 0
US average 0
Other Counties in Missouri
Air quality comparison for nearby counties in Missouri.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Clinton County.
Allegan County, Michigan
AQI 43 · 71.2% good
Allen County, Ohio
AQI 43 · 65.9% good
Ashtabula County, Ohio
AQI 43 · 81.2% good
Bell County, Kentucky
AQI 43 · 63.5% good
Boise County, Idaho
AQI 43 · 72.9% good
Brazos County, Texas
AQI 43 · 63.4% good
What Clinton 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 43 means for exposure. Health guidance
- See how Clinton County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Clinton County with its Missouri neighbours before drawing a conclusion about the region. All of Missouri
Based on 91 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 Clinton County, Missouri? ▼
Clinton County has a median Air Quality Index (AQI) of 43, rated "Good." 84.6% of monitored days (77 out of 91) had good air quality in 2025.
What is the main pollutant in Clinton County? ▼
The primary pollutant in Clinton County is Ozone (O3), which was the main AQI driver on 91 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Clinton County have? ▼
In 2025, Clinton County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 74.
Is the air quality in Clinton County getting better or worse? ▼
Air quality in Clinton County is worsening based on 5-year trends (2020-2025). Best year: 2020 with 226 good days. Worst year: 2025 with 77 good days.
What does AQI 43 mean for health? ▼
Clinton County's median AQI of 43 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 Clinton County compare to other counties in Missouri? ▼
Clinton County has 84.6% good air days. Nearby counties in Missouri: Andrew (84.3% good), Boone (89.1% good), Buchanan (64.2% good), Callaway (85.6% good), Cass (82.2% good), Cedar (81.8% good).
What is the 90th percentile AQI in Clinton County? ▼
The 90th percentile AQI for Clinton County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 74 (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.