Median AQI
42
Good
Oklahoma · County air quality · 2025
Sequoyah County, Oklahoma
Median AQI 42 (Good). 72.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 42
- Median AQI
- 72.0%
- Good-air days
- 0
- Unhealthy days
- 35%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Sequoyah County's air is good on balance, more polluted than the median US county, a median AQI of 42 with 72.0% of 211 monitored days in the Good band, driven mainly by PM2.5.
- 42
- median AQI · Good
- 72.0%
- days rated Good
- PM2.5
- main pollutant
- 35%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 138.
Data updated July 2026
- Good · 152 d · 72.0%
- Moderate · 57 d · 27.0%
- USG · 2 d · 0.9%
How did Sequoyah County's air break down in 2025?
Across 211 monitored days, 152 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 138 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 211 days monitored. Median AQI: 42 (Good).
Insights: Sequoyah County, Oklahoma. EPA monitors recorded a median Air Quality Index of 42 across 211 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 152 (72%) fell in the Good band (AQI 0–50), 57 (27%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 57, while the worst single-day peak hit 138 (USG). Residents averaged about 21.6 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (142 days), Ozone (69 days). Across the 2020–2025 trend window, good days shifted by -152 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 138, usg but never Unhealthy. Nearby counties show comparable readings: Adair (59.2% good, AQI 45); Canadian (78.0% good, AQI 44); Carter (80.9% good, AQI 33); Cleveland (53.7% good, AQI 49); Comanche (63.8% good, AQI 45); Creek (80.1% good, AQI 43).
Air Quality Summary
Good Days
72.0%
152 of 211 monitored days
-3.0pp vs 75% target
Max AQI Recorded
138
USG
Health Grade
Moderate
90th-pct AQI 57
Sequoyah County, Good days share 72.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Sequoyah 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 211 monitored days across EPA AQI categories.
Good
152
72%
Moderate
57
27%
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 Sequoyah County.
- PM2.5 · 142 days · 67.3%
- Ozone · 69 days · 32.7%
Health Impact Assessment
Moderate
Sequoyah County's air quality is rated Moderate based on 72.0% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 72.0% of monitored days in 2025, with a median AQI of 42. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 142 of 211 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Sequoyah County. Best year: 2020 (304 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 304 | 57 | 1 | 0 | 37 | 141 |
| 2021 | 250 | 108 | 2 | 0 | 41 | 122 |
| 2022 | 278 | 84 | 2 | 0 | 42 | 122 |
| 2023 | 227 | 138 | 0 | 0 | 46 | 84 |
| 2024 | 252 | 114 | 0 | 0 | 44 | 97 |
| 2025 | 152 | 57 | 2 | 0 | 42 | 138 |
How does Sequoyah County compare?
How Sequoyah County compares
Good-day share worse than US avg
Sequoyah County 72.0%
Adair County, Oklahoma 59.2%
US average 76.5%
Median AQI worse than US avg
Sequoyah County 42
Adair County, Oklahoma 45
US average 38
Unhealthy days / yr about average
Sequoyah County 0
Adair County, Oklahoma 2
US average 0
Other Counties in Oklahoma
Air quality comparison for nearby counties in Oklahoma.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Sequoyah County.
Adams County, Pennsylvania
AQI 42 · 73.8% good
Anderson County, Tennessee
AQI 42 · 91.0% good
Andrew County, Missouri
AQI 42 · 84.3% good
Armstrong County, Pennsylvania
AQI 42 · 68.1% good
Baldwin County, Alabama
AQI 42 · 72.2% good
Belmont County, Ohio
AQI 42 · 63.0% good
What Sequoyah 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 42 means for exposure. Health guidance
- See how Sequoyah County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Sequoyah County with its Oklahoma neighbours before drawing a conclusion about the region. All of Oklahoma
Based on 211 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 Sequoyah County, Oklahoma? ▼
Sequoyah County has a median Air Quality Index (AQI) of 42, rated "Good." 72.0% of monitored days (152 out of 211) had good air quality in 2025.
What is the main pollutant in Sequoyah County? ▼
The primary pollutant in Sequoyah County is Fine Particles (PM2.5), which was the main AQI driver on 142 days (67% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Sequoyah County have? ▼
In 2025, Sequoyah County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 138.
Is the air quality in Sequoyah County getting better or worse? ▼
Air quality in Sequoyah County is worsening based on 5-year trends (2020-2025). Best year: 2020 with 304 good days. Worst year: 2025 with 152 good days.
What does AQI 42 mean for health? ▼
Sequoyah County's median AQI of 42 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 Sequoyah County compare to other counties in Oklahoma? ▼
Sequoyah County has 72.0% good air days. Nearby counties in Oklahoma: Adair (59.2% good), Canadian (78.0% good), Carter (80.9% good), Cleveland (53.7% good), Comanche (63.8% good), Creek (80.1% good).
What is the 90th percentile AQI in Sequoyah County? ▼
The 90th percentile AQI for Sequoyah County is 57, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 138 (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.