Median AQI
35
Good
Arkansas · County air quality · 2025
Clark County, Arkansas
Median AQI 35 (Good). 97.5% of monitored days rated Good, direct from EPA Air Quality System stations.
- 35
- Median AQI
- 97.5%
- Good-air days
- 0
- Unhealthy days
- 94%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Clark County's air is good on balance, among the cleanest 10% of US counties, a median AQI of 35 with 97.5% of 241 monitored days in the Good band, driven mainly by Ozone.
- 35
- median AQI · Good
- 97.5%
- days rated Good
- Ozone
- main pollutant
- 94%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 74.
Data updated July 2026
- Good · 235 d · 97.5%
- Moderate · 6 d · 2.5%
How did Clark County's air break down in 2025?
Across 241 monitored days, 235 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). 241 days monitored. Median AQI: 35 (Good).
Insights: Clark County, Arkansas. EPA monitors recorded a median Air Quality Index of 35 across 241 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 235 (98%) fell in the Good band (AQI 0–50), 6 (2%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 46, while the worst single-day peak hit 74 (Moderate). Residents averaged about 29.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (241 days). Across the 2020–2025 trend window, good days shifted by -106 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: Arkansas (51.6% good, AQI 49); Ashley (53.9% good, AQI 49); Crittenden (79.8% good, AQI 41); Garland (52.8% good, AQI 49); Jackson (65.9% good, AQI 44); Newton (93.0% good, AQI 38).
Air Quality Summary
Good Days
97.5%
235 of 241 monitored days
22.5pp vs 75% target
Max AQI Recorded
74
Moderate
Health Grade
Excellent
90th-pct AQI 46
Clark County, Good days share 97.5%
National avg
Share of monitored days at AQI 0-50 (Good band).
Clark 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 241 monitored days across EPA AQI categories.
Good
235
98%
Moderate
6
2%
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 Clark County.
- Ozone · 241 days · 100.0%
Health Impact Assessment
Excellent
Clark County's air quality is rated Excellent based on 97.5% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 97.5% of monitored days in 2025, with a median AQI of 35. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 241 of 241 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Clark County. Best year: 2022 (350 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 341 | 1 | 0 | 0 | 29 | 67 |
| 2021 | 328 | 10 | 0 | 0 | 32 | 90 |
| 2022 | 350 | 13 | 0 | 0 | 35 | 90 |
| 2023 | 321 | 30 | 0 | 0 | 35 | 87 |
| 2024 | 336 | 24 | 0 | 0 | 35 | 93 |
| 2025 | 235 | 6 | 0 | 0 | 35 | 74 |
How does Clark County compare?
How Clark County compares
Good-day share better than US avg
Clark County 97.5%
Arkansas County, Arkansas 51.6%
US average 76.5%
Median AQI better than US avg
Clark County 35
Arkansas County, Arkansas 49
US average 38
Unhealthy days / yr about average
Clark County 0
Arkansas County, Arkansas 0
US average 0
Other Counties in Arkansas
Air quality comparison for nearby counties in Arkansas.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Clark County.
Androscoggin County, Maine
AQI 35 · 85.5% good
Asotin County, Washington
AQI 35 · 73.8% good
Benton County, Washington
AQI 35 · 88.9% good
Benzie County, Michigan
AQI 35 · 91.1% good
Brooke County, West Virginia
AQI 35 · 79.3% good
Bucks County, Pennsylvania
AQI 35 · 87.5% good
What Clark 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 35 means for exposure. Health guidance
- See how Clark County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Clark County with its Arkansas neighbours before drawing a conclusion about the region. All of Arkansas
Based on 241 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 Clark County, Arkansas? ▼
Clark County has a median Air Quality Index (AQI) of 35, rated "Good." 97.5% of monitored days (235 out of 241) had good air quality in 2025.
What is the main pollutant in Clark County? ▼
The primary pollutant in Clark County is Ozone (O3), which was the main AQI driver on 241 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Clark County have? ▼
In 2025, Clark County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 74.
Is the air quality in Clark County getting better or worse? ▼
Air quality in Clark County is worsening based on 5-year trends (2020-2025). Best year: 2022 with 350 good days. Worst year: 2025 with 235 good days.
What does AQI 35 mean for health? ▼
Clark County's median AQI of 35 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 Clark County compare to other counties in Arkansas? ▼
Clark County has 97.5% good air days. Nearby counties in Arkansas: Arkansas (51.6% good), Ashley (53.9% good), Crittenden (79.8% good), Garland (52.8% good), Jackson (65.9% good), Newton (93.0% good).
What is the 90th percentile AQI in Clark County? ▼
The 90th percentile AQI for Clark County is 46, 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.