Median AQI
45
Good
Iowa · County air quality · 2025
Clinton County, Iowa
Median AQI 45 (Good). 59.9% of monitored days rated Good, direct from EPA Air Quality System stations.
- 45
- Median AQI
- 59.9%
- Good-air days
- 1
- Unhealthy days
- 14%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Clinton County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 45 with 59.9% of 304 monitored days in the Good band, driven mainly by PM2.5.
- 45
- median AQI · Good
- 59.9%
- days rated Good
- PM2.5
- main pollutant
- 14%
- cleaner than US counties
1 day reached Unhealthy or worse; the worst single reading hit AQI 166.
Data updated July 2026
- Good · 182 d · 59.9%
- Moderate · 119 d · 39.1%
- USG · 2 d · 0.7%
- Unhealthy · 1 d · 0.3%
How did Clinton County's air break down in 2025?
Across 304 monitored days, 182 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 166 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 304 days monitored. Median AQI: 45 (Good).
Insights: Clinton County, Iowa. EPA monitors recorded a median Air Quality Index of 45 across 304 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 182 (60%) fell in the Good band (AQI 0–50), 119 (39%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 71, while the worst single-day peak hit 166 (Unhealthy). Residents averaged about 18.0 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (166 days), Ozone (138 days). Across the 2020–2025 trend window, good days shifted by -17 and the median AQI moved +0 points, placing the multi-year trajectory at stable. Residents and visitors experienced 1 unhealthy-or-worse days combined, periods when the EPA recommends sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Black Hawk (56.6% good, AQI 48); Bremer (87.1% good, AQI 38); Harrison (83.0% good, AQI 39); Johnson (71.0% good, AQI 36); Linn (61.2% good, AQI 44); Montgomery (68.8% good, AQI 43).
Air Quality Summary
Good Days
59.9%
182 of 304 monitored days
-15.1pp vs 75% target
Max AQI Recorded
166
Unhealthy
Health Grade
Moderate
90th-pct AQI 71
Clinton County, Good days share 59.9%
National avg
Share of monitored days at AQI 0-50 (Good band).
Clinton County, Unhealthy-or-worse share 0.3%
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 304 monitored days across EPA AQI categories.
Good
182
60%
Moderate
119
39%
USG
2
1%
Unhealthy
1
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Clinton County.
- PM2.5 · 166 days · 54.6%
- Ozone · 138 days · 45.4%
Health Impact Assessment
Moderate
Clinton County's air quality is rated Moderate based on 59.9% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 2 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 166. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is PM2.5, driving AQI on 166 of 304 monitored days.
5-Year Air Quality Trend
Air quality is stable in Clinton County. Best year: 2024 (230 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 199 | 125 | 0 | 0 | 45 | 87 |
| 2021 | 134 | 229 | 2 | 0 | 55 | 112 |
| 2022 | 165 | 198 | 1 | 0 | 52 | 107 |
| 2023 | 132 | 215 | 14 | 3 | 54 | 235 |
| 2024 | 230 | 135 | 0 | 0 | 46 | 90 |
| 2025 | 182 | 119 | 2 | 1 | 45 | 166 |
How does Clinton County compare?
How Clinton County compares
Good-day share worse than US avg
Clinton County 59.9%
Black Hawk County, Iowa 56.6%
US average 76.5%
Median AQI worse than US avg
Clinton County 45
Black Hawk County, Iowa 48
US average 38
Unhealthy days / yr worse than US avg
Clinton County 1
Black Hawk County, Iowa 1
US average 0
Other Counties in Iowa
Air quality comparison for nearby counties in Iowa.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Clinton County.
Adair County, Oklahoma
AQI 45 · 59.2% good
Allen County, Indiana
AQI 45 · 58.2% good
Atascosa County, Texas
AQI 45 · 58.0% good
Baker County, Florida
AQI 45 · 69.1% good
Carson City County, Nevada
AQI 45 · 79.3% good
Comanche County, Oklahoma
AQI 45 · 63.8% good
What Clinton County's air means for you
On most days the air here is fine, but PM2.5 drives 1 unhealthy-or-worse day a year that sensitive groups should plan around.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 45 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 Iowa neighbours before drawing a conclusion about the region. All of Iowa
Based on 304 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, Iowa? ▼
Clinton County has a median Air Quality Index (AQI) of 45, rated "Good." 59.9% of monitored days (182 out of 304) had good air quality in 2025.
What is the main pollutant in Clinton County? ▼
The primary pollutant in Clinton County is Fine Particles (PM2.5), which was the main AQI driver on 166 days (55% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Clinton County have? ▼
In 2025, Clinton County recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 166.
Is the air quality in Clinton County getting better or worse? ▼
Air quality in Clinton County is stable based on 5-year trends (2020-2025). Best year: 2024 with 230 good days. Worst year: 2023 with 132 good days.
What does AQI 45 mean for health? ▼
Clinton County's median AQI of 45 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 Iowa? ▼
Clinton County has 59.9% good air days. Nearby counties in Iowa: Black Hawk (56.6% good), Bremer (87.1% good), Harrison (83.0% good), Johnson (71.0% good), Linn (61.2% good), Montgomery (68.8% good).
What is the 90th percentile AQI in Clinton County? ▼
The 90th percentile AQI for Clinton County is 71, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 166 (Unhealthy).
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.