Median AQI
45
Good
Ohio · County air quality · 2025
Scioto County, Ohio
Median AQI 45 (Good). 58.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 45
- Median AQI
- 58.6%
- Good-air days
- 1
- Unhealthy days
- 13%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Scioto County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 45 with 58.6% of 273 monitored days in the Good band, driven mainly by PM2.5.
- 45
- median AQI · Good
- 58.6%
- days rated Good
- PM2.5
- main pollutant
- 13%
- cleaner than US counties
1 day reached Unhealthy or worse; the worst single reading hit AQI 238.
Data updated July 2026
- Good · 160 d · 58.6%
- Moderate · 111 d · 40.7%
- USG · 1 d · 0.4%
- Very Unhealthy · 1 d · 0.4%
How did Scioto County's air break down in 2025?
Across 273 monitored days, 160 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 238 (Very Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 273 days monitored. Median AQI: 45 (Good).
Insights: Scioto County, Ohio. EPA monitors recorded a median Air Quality Index of 45 across 273 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 160 (59%) fell in the Good band (AQI 0–50), 111 (41%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 64, while the worst single-day peak hit 238 (Very Unhealthy). Residents averaged about 17.6 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (266 days), PM10 (7 days). Across the 2020–2025 trend window, good days shifted by -187 and the median AQI moved +31 points, placing the multi-year trajectory at worsening. 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: Allen (65.9% good, AQI 43); Ashtabula (81.2% good, AQI 43); Athens (80.3% good, AQI 33); Belmont (63.0% good, AQI 42); Butler (33.3% good, AQI 55); Clark (59.4% good, AQI 46).
Air Quality Summary
Good Days
58.6%
160 of 273 monitored days
-16.4pp vs 75% target
Max AQI Recorded
238
Very Unhealthy
Health Grade
Moderate
90th-pct AQI 64
Scioto County, Good days share 58.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
Scioto County, Unhealthy-or-worse share 0.4%
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 273 monitored days across EPA AQI categories.
Good
160
59%
Moderate
111
41%
USG
1
0%
Unhealthy
0
0%
Very Unhealthy
1
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Scioto County.
- PM2.5 · 266 days · 97.4%
- PM10 · 7 days · 2.6%
Health Impact Assessment
Moderate
Scioto County's air quality is rated Moderate based on 58.6% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality reached unhealthy levels on 1 days in 2025 (0 Unhealthy, 1 Very Unhealthy). Sensitive groups, including people with asthma, COPD, cardiovascular conditions, children, and adults over 65, should review the daily breakdown below and follow local air-quality advisories on high-AQI days.
Sensitive group advisory
People with asthma, COPD, heart disease, children, pregnant women, and adults 65+ should follow EPA AQI alerts daily and limit outdoor exertion when AQI exceeds 100. Real-time conditions: airnow.gov.
The dominant pollutant is PM2.5, driving AQI on 266 of 273 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Scioto County. Best year: 2020 (347 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 347 | 19 | 0 | 0 | 14 | 93 |
| 2021 | 333 | 32 | 0 | 0 | 16 | 86 |
| 2022 | 340 | 25 | 0 | 0 | 17 | 74 |
| 2023 | 223 | 135 | 5 | 2 | 44 | 172 |
| 2024 | 248 | 118 | 0 | 0 | 40 | 80 |
| 2025 | 160 | 111 | 1 | 0 | 45 | 238 |
How does Scioto County compare?
How Scioto County compares
Good-day share worse than US avg
Scioto County 58.6%
Allen County, Ohio 65.9%
US average 76.5%
Median AQI worse than US avg
Scioto County 45
Allen County, Ohio 43
US average 38
Unhealthy days / yr worse than US avg
Scioto County 1
Allen County, Ohio 0
US average 0
Other Counties in Ohio
Air quality comparison for nearby counties in Ohio.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Scioto 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
Clinton County, Iowa
AQI 45 · 59.9% good
What Scioto 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 Scioto County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Scioto County with its Ohio neighbours before drawing a conclusion about the region. All of Ohio
Based on 273 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 Scioto County, Ohio? ▼
Scioto County has a median Air Quality Index (AQI) of 45, rated "Good." 58.6% of monitored days (160 out of 273) had good air quality in 2025.
What is the main pollutant in Scioto County? ▼
The primary pollutant in Scioto County is Fine Particles (PM2.5), which was the main AQI driver on 266 days (97% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Scioto County have? ▼
In 2025, Scioto County recorded 1 unhealthy air days (0 Unhealthy, 1 Very Unhealthy, 0 Hazardous). The maximum AQI reached 238.
Is the air quality in Scioto County getting better or worse? ▼
Air quality in Scioto County is worsening based on 5-year trends (2020-2025). Best year: 2020 with 347 good days. Worst year: 2025 with 160 good days.
What does AQI 45 mean for health? ▼
Scioto 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 Scioto County compare to other counties in Ohio? ▼
Scioto County has 58.6% good air days. Nearby counties in Ohio: Allen (65.9% good), Ashtabula (81.2% good), Athens (80.3% good), Belmont (63.0% good), Butler (33.3% good), Clark (59.4% good).
What is the 90th percentile AQI in Scioto County? ▼
The 90th percentile AQI for Scioto County is 64, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 238 (Very 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.