Median AQI
34
Good
Arkansas · County air quality · 2025
Clark County, Arkansas
Median AQI 34 (Good). 96.7% of monitored days rated Good, direct from EPA Air Quality System stations.
- 34
- Median AQI
- 96.7%
- Good-air days
- 0
- Unhealthy days
- 95%
- Cleaner than US counties
Clark County's 2025 annual median AQI is 34 (Good), with 96.7% Good days
According to the U.S. EPA Air Quality System, Clark County, Arkansas posted a 2025 median AQI of 34 (Good) across 363 monitored days, with 96.7% 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
- Clark County's 96.7% Good-day share places it cleaner than 95% of US counties in 2025.
- Closest median-AQI peer
- Androscoggin County (85.2% Good, median AQI 34) is the closest nationwide median-AQI peer to Clark County.
- 2020–2025 trend
- Clark County's floor-qualifying Good-day share is worsening from 2020 to 2025 (99.7% → 96.7%).
- Median AQI
- Median AQI: 34
The verdict
According to EPA Air Quality System monitoring data, Clark County's air is good on balance, among the cleanest 5% of US counties, a median AQI of 34 with 96.7% of 363 monitored days in the Good band, driven mainly by Ozone.
- 34
- median AQI · Good
- 96.7%
- days rated Good
- Ozone
- main pollutant
- 95%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 84.
Annual release change
What changed in the 2025 EPA annual release
- Clark County's Good-day share rose from 93.3% to 96.7% between the 2024 and 2025 EPA annual releases, a change of +3.4 percentage points.
Data updated August 2026
- Good · 351 d · 96.7%
- Moderate · 12 d · 3.3%
How did Clark County's air break down in 2025?
Across 363 monitored days, 351 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 84 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 363 days monitored. Median AQI: 34 (Good).
Insights: Clark County, Arkansas. EPA monitors recorded a median Air Quality Index of 34 across 363 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 351 (97%) fell in the Good band (AQI 0–50), 12 (3%) 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 84 (Moderate). Residents averaged about 29.0 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (363 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -3.0 points (measured against 342 monitored days in 2020 and 363 in 2025, so raw day counts are not comparable) and the median AQI moved +5 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 84, moderate but never Unhealthy. Nearby counties show comparable readings: Arkansas (52.9% good, AQI 48); Ashley (55.7% good, AQI 48); Crittenden (80.8% good, AQI 39); Garland (49.2% good, AQI 51); Jackson (62.3% good, AQI 46); Newton (90.4% good, AQI 38).
Air Quality Summary
Good Days
96.7%
351 of 363 monitored days
21.7pp vs 75% target
Max AQI Recorded
84
Moderate
Health Grade
Excellent
90th-pct AQI 46
Clark County, Good days share 96.7%
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 363 monitored days across EPA AQI categories.
Good
351
97%
Moderate
12
3%
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 · 363 days · 100.0%
Health Impact Assessment
Excellent
Clark County's air quality is rated Excellent based on 96.7% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 96.7% of monitored days in 2025, with a median AQI of 34. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 363 of 363 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Clark County. Highest Good-day share: 2020 (99.7%, 341 of 342 monitored 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 | 351 | 12 | 0 | 0 | 34 | 84 |
How does Clark County compare?
How Clark County compares
Good-day share better than US avg
Clark County 96.7%
Androscoggin County, Maine 85.2%
US average 76.0%
Median AQI better than US avg
Clark County 34
Androscoggin County, Maine 34
US average 39
Unhealthy days / yr better than US avg
Clark County 0
Androscoggin County, Maine 0
US average 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Clark County (34), not geographic neighbors.
Androscoggin County, Maine
Median AQI 34 · 85.2% Good-day share
Archuleta County, Colorado
Median AQI 34 · 83.0% Good-day share
Bristol City County, Virginia
Median AQI 34 · 78.0% Good-day share
Brown County, Indiana
Median AQI 34 · 95.9% Good-day share
Clay County, South Dakota
Median AQI 34 · 87.8% Good-day share
Dawson County, Georgia
Median AQI 34 · 95.1% 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).
Sevier County, Tennessee
96.7% Good-day share · median AQI 40
Hanover County, Virginia
96.7% Good-day share · median AQI 36
Merrimack County, New Hampshire
96.7% Good-day share · median AQI 37
Caroline County, Virginia
96.7% Good-day share · median AQI 35
York County, Maine
96.7% Good-day share · median AQI 34
Suffolk City County, Virginia
96.7% Good-day share · median AQI 38
Arkansas counties on the map
Geographic containment only, other monitored counties in Arkansas, independent of AQI or pollutant match.
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 34 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 363 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 Clark County, Arkansas? ▼
Clark County has a median Air Quality Index (AQI) of 34, rated "Good." 96.7% of monitored days (351 out of 363) 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 363 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 84.
Is the air quality in Clark County getting better or worse? ▼
Air quality in Clark 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 99.7% (341 of 342 days). Lowest qualifying Good-day share: 2023 at 91.5% (321 of 351 days).
What does AQI 34 mean for health? ▼
Clark County's median AQI of 34 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Clark County compare to other counties in Arkansas? ▼
Clark County has 96.7% good air days. Nearby counties in Arkansas: Arkansas (52.9% good), Ashley (55.7% good), Crittenden (80.8% good), Garland (49.2% good), Jackson (62.3% good), Newton (90.4% 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 84 (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. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Clark County, Arkansas · 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.