Median AQI
41
Good
Ohio · County air quality · 2025
Clinton County, Ohio
Median AQI 41 (Good). 83.1% of monitored days rated Good, direct from EPA Air Quality System stations.
- 41
- Median AQI
- 83.1%
- Good-air days
- 0
- Unhealthy days
- 64%
- Cleaner than US counties
Clinton County's 2025 annual median AQI is 41 (Good), with 83.1% Good days
According to the U.S. EPA Air Quality System, Clinton County, Ohio posted a 2025 median AQI of 41 (Good) across 243 monitored days, with 83.1% 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
- Clinton County's 83.1% Good-day share places it cleaner than 64% of US counties in 2025.
- Closest median-AQI peer
- Armstrong County (70.5% Good, median AQI 41) is the closest nationwide median-AQI peer to Clinton County.
- 2020–2025 trend
- Clinton County's floor-qualifying Good-day share is worsening from 2020 to 2025 (89.5% → 83.1%).
- Median AQI
- Median AQI: 41
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 41 with 83.1% of 243 monitored days in the Good band, driven mainly by Ozone.
- 41
- median AQI · Good
- 83.1%
- days rated Good
- Ozone
- main pollutant
- 64%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 112.
Annual release change
What changed in the 2025 EPA annual release
- Clinton County's Good-day share rose from 73.3% to 83.1% between the 2024 and 2025 EPA annual releases, a change of +9.8 percentage points.
- Clinton County's median AQI fell from 44 to 41 between the 2024 and 2025 EPA annual releases, a change of -3 points.
Data updated August 2026
- Good · 202 d · 83.1%
- Moderate · 38 d · 15.6%
- USG · 3 d · 1.2%
How did Clinton County's air break down in 2025?
Across 243 monitored days, 202 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 112 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 243 days monitored. Median AQI: 41 (Good).
Insights: Clinton County, Ohio. EPA monitors recorded a median Air Quality Index of 41 across 243 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 202 (83%) fell in the Good band (AQI 0–50), 38 (16%) registered Moderate readings, and 3 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 112 (USG). Residents averaged about 24.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (243 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -6.4 points (measured against 229 monitored days in 2020 and 243 in 2025, so raw day counts are not comparable) and the median AQI moved +2 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 112, usg but never Unhealthy. Nearby counties show comparable readings: Allen (67.0% good, AQI 42); Ashtabula (81.2% good, AQI 43); Athens (83.4% good, AQI 31); Belmont (63.0% good, AQI 42); Butler (33.1% good, AQI 55); Clark (61.4% good, AQI 45).
Air Quality Summary
Good Days
83.1%
202 of 243 monitored days
8.1pp vs 75% target
Max AQI Recorded
112
USG
Health Grade
Good
90th-pct AQI 61
Clinton County, Good days share 83.1%
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 243 monitored days across EPA AQI categories.
Good
202
83%
Moderate
38
16%
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 Clinton County.
- Ozone · 243 days · 100.0%
Health Impact Assessment
Good
Clinton County's air quality is rated Good based on 83.1% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 83.1% of monitored days in 2025, with a median AQI of 41. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 243 of 243 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Clinton County. Highest Good-day share: 2020 (89.5%, 205 of 229 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 205 | 24 | 0 | 0 | 39 | 97 |
| 2021 | 209 | 31 | 0 | 0 | 39 | 84 |
| 2022 | 216 | 28 | 1 | 0 | 40 | 140 |
| 2023 | 199 | 39 | 4 | 0 | 44 | 129 |
| 2024 | 176 | 60 | 4 | 0 | 44 | 112 |
| 2025 | 202 | 38 | 3 | 0 | 41 | 112 |
How does Clinton County compare?
How Clinton County compares
Good-day share better than typical
Clinton County 83.1%
Armstrong County, Pennsylvania 70.5%
Typical US county 76.0%
Median AQI worse than typical
Clinton County 41
Armstrong County, Pennsylvania 41
Typical US county 39
Unhealthy days / yr better than typical
Clinton County 0
Armstrong County, Pennsylvania 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Clinton County (41), not geographic neighbors.
Armstrong County, Pennsylvania
Median AQI 41 · 70.5% Good-day share
Benewah County, Idaho
Median AQI 41 · 63.4% Good-day share
Berrien County, Michigan
Median AQI 41 · 80.9% Good-day share
Callaway County, Missouri
Median AQI 41 · 89.6% Good-day share
Cambria County, Pennsylvania
Median AQI 41 · 74.5% Good-day share
Cass County, Missouri
Median AQI 41 · 77.6% 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).
Genesee County, Michigan
83.2% Good-day share · median AQI 38
Montgomery County, Maryland
83.1% Good-day share · median AQI 39
Harrison County, Iowa
83.0% Good-day share · median AQI 39
Onondaga County, New York
83.2% Good-day share · median AQI 36
San Miguel County, Colorado
83.0% Good-day share · median AQI 36
Archuleta County, Colorado
83.0% Good-day share · median AQI 34
Ohio counties on the map
Geographic containment only, other monitored counties in Ohio, independent of AQI or pollutant match.
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 41 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 Ohio neighbours before drawing a conclusion about the region. All of Ohio
Based on 243 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 Clinton County, Ohio? ▼
Clinton County has a median Air Quality Index (AQI) of 41, rated "Good." 83.1% of monitored days (202 out of 243) 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 243 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 112.
Is the air quality in Clinton County getting better or worse? ▼
Air quality in Clinton County is worsening across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2020 at 89.5% (205 of 229 days). Lowest qualifying Good-day share: 2024 at 73.3% (176 of 240 days).
What does AQI 41 mean for health? ▼
Clinton County's median AQI of 41 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Clinton County compare to other counties in Ohio? ▼
Clinton County has 83.1% good air days. Nearby counties in Ohio: Allen (67.0% good), Ashtabula (81.2% good), Athens (83.4% good), Belmont (63.0% good), Butler (33.1% good), Clark (61.4% 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 112 (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 Clinton County, Ohio · 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.