Median AQI
51
Moderate
Ohio · County air quality · 2025
Stark County, Ohio
Median AQI 51 (Moderate). 49.5% of monitored days rated Good, direct from EPA Air Quality System stations.
- 51
- Median AQI
- 49.5%
- Good-air days
- 0
- Unhealthy days
- 6%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Stark County's air is moderate on balance, among the most polluted counties nationally, a median AQI of 51 with 49.5% of 273 monitored days in the Good band, driven mainly by PM2.5.
- 51
- median AQI · Moderate
- 49.5%
- days rated Good
- PM2.5
- main pollutant
- 6%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 124.
Data updated July 2026
- Good · 135 d · 49.5%
- Moderate · 136 d · 49.8%
- USG · 2 d · 0.7%
How did Stark County's air break down in 2025?
Across 273 monitored days, 135 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 124 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 273 days monitored. Median AQI: 51 (Moderate).
Insights: Stark County, Ohio. EPA monitors recorded a median Air Quality Index of 51 across 273 measured days in 2025, earning a Moderate classification and a Poor health grade. Of those days, 135 (49%) fell in the Good band (AQI 0–50), 136 (50%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 72, while the worst single-day peak hit 124 (USG). Residents averaged about 14.8 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (174 days), Ozone (99 days). Across the 2020–2025 trend window, good days shifted by -67 and the median AQI moved +4 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 124, usg but never Unhealthy. 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
49.5%
135 of 273 monitored days
-25.5pp vs 75% target
Max AQI Recorded
124
USG
Health Grade
Poor
90th-pct AQI 72
Stark County, Good days share 49.5%
National avg
Share of monitored days at AQI 0-50 (Good band).
Stark 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 273 monitored days across EPA AQI categories.
Good
135
49%
Moderate
136
50%
USG
2
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 Stark County.
- PM2.5 · 174 days · 63.7%
- Ozone · 99 days · 36.3%
Health Impact Assessment
Poor
Stark County's air quality is rated Poor based on 49.5% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 49.5% of monitored days in 2025, with a median AQI of 51. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 174 of 273 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Stark County. Best year: 2022 (206 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 202 | 152 | 4 | 0 | 47 | 119 |
| 2021 | 154 | 208 | 3 | 0 | 53 | 127 |
| 2022 | 206 | 157 | 2 | 0 | 49 | 136 |
| 2023 | 163 | 192 | 7 | 1 | 52 | 283 |
| 2024 | 192 | 174 | 0 | 0 | 48 | 93 |
| 2025 | 135 | 136 | 2 | 0 | 51 | 124 |
How does Stark County compare?
How Stark County compares
Good-day share worse than US avg
Stark County 49.5%
Allen County, Ohio 65.9%
US average 76.5%
Median AQI worse than US avg
Stark County 51
Allen County, Ohio 43
US average 38
Unhealthy days / yr about average
Stark County 0
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 Stark County.
Arapahoe County, Colorado
AQI 51 · 47.3% good
Bibb County, Georgia
AQI 51 · 49.5% good
East Baton Rouge County, Louisiana
AQI 51 · 49.3% good
Eddy County, New Mexico
AQI 51 · 46.9% good
Hillsborough County, Florida
AQI 51 · 49.3% good
Jefferson County, Colorado
AQI 51 · 46.5% good
What Stark County's air means for you
The air here stays in the breathable range year-round, with PM2.5 the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 51 means for exposure. Health guidance
- See how Stark County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Stark 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 Stark County, Ohio? ▼
Stark County has a median Air Quality Index (AQI) of 51, rated "Moderate." 49.5% of monitored days (135 out of 273) had good air quality in 2025.
What is the main pollutant in Stark County? ▼
The primary pollutant in Stark County is Fine Particles (PM2.5), which was the main AQI driver on 174 days (64% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Stark County have? ▼
In 2025, Stark County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 124.
Is the air quality in Stark County getting better or worse? ▼
Air quality in Stark County is worsening based on 5-year trends (2020-2025). Best year: 2022 with 206 good days. Worst year: 2025 with 135 good days.
What does AQI 51 mean for health? ▼
Stark County's median AQI of 51 falls in the "Moderate" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Stark County compare to other counties in Ohio? ▼
Stark County has 49.5% 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 Stark County? ▼
The 90th percentile AQI for Stark County is 72, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 124 (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.
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.