Median AQI
33
Good
Oklahoma · County air quality · 2025
Carter County, Oklahoma
Median AQI 33 (Good). 80.9% of monitored days rated Good, direct from EPA Air Quality System stations.
- 33
- Median AQI
- 80.9%
- Good-air days
- 1
- Unhealthy days
- 55%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Carter County's air is good on balance, cleaner than the median US county, a median AQI of 33 with 80.9% of 251 monitored days in the Good band, driven mainly by PM2.5.
- 33
- median AQI · Good
- 80.9%
- days rated Good
- PM2.5
- main pollutant
- 55%
- cleaner than US counties
1 day reached Unhealthy or worse; the worst single reading hit AQI 155.
Data updated July 2026
- Good · 203 d · 80.9%
- Moderate · 47 d · 18.7%
- Unhealthy · 1 d · 0.4%
How did Carter County's air break down in 2025?
Across 251 monitored days, 203 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 155 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 251 days monitored. Median AQI: 33 (Good).
Insights: Carter County, Oklahoma. EPA monitors recorded a median Air Quality Index of 33 across 251 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 203 (81%) fell in the Good band (AQI 0–50), 47 (19%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 55, while the worst single-day peak hit 155 (Unhealthy). Residents averaged about 24.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (251 days). Across the 2020–2025 trend window, good days shifted by +2 and the median AQI moved -14 points, placing the multi-year trajectory at improving. 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: Adair (59.2% good, AQI 45); Canadian (78.0% good, AQI 44); Cleveland (53.7% good, AQI 49); Comanche (63.8% good, AQI 45); Creek (80.1% good, AQI 43); Dewey (56.6% good, AQI 49).
Air Quality Summary
Good Days
80.9%
203 of 251 monitored days
5.9pp vs 75% target
Max AQI Recorded
155
Unhealthy
Health Grade
Good
90th-pct AQI 55
Carter County, Good days share 80.9%
National avg
Share of monitored days at AQI 0-50 (Good band).
Carter 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 251 monitored days across EPA AQI categories.
Good
203
81%
Moderate
47
19%
USG
0
0%
Unhealthy
1
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Carter County.
- PM2.5 · 251 days · 100.0%
Health Impact Assessment
Good
Carter County's air quality is rated Good based on 80.9% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 0 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 155. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is PM2.5, driving AQI on 251 of 251 monitored days.
5-Year Air Quality Trend
Air quality is improving in Carter County. Best year: 2022 (254 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 201 | 143 | 1 | 0 | 47 | 147 |
| 2021 | 186 | 129 | 1 | 0 | 46 | 118 |
| 2022 | 254 | 88 | 0 | 1 | 37 | 160 |
| 2023 | 189 | 138 | 17 | 0 | 48 | 136 |
| 2024 | 217 | 132 | 14 | 0 | 48 | 143 |
| 2025 | 203 | 47 | 0 | 1 | 33 | 155 |
How does Carter County compare?
How Carter County compares
Good-day share better than US avg
Carter County 80.9%
Adair County, Oklahoma 59.2%
US average 76.5%
Median AQI better than US avg
Carter County 33
Adair County, Oklahoma 45
US average 38
Unhealthy days / yr worse than US avg
Carter County 1
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 Carter County.
Ascension County, Louisiana
AQI 33 · 94.1% good
Athens County, Ohio
AQI 33 · 80.3% good
Brazoria County, Texas
AQI 33 · 84.8% good
Bristol City County, Virginia
AQI 33 · 78.3% good
Codington County, South Dakota
AQI 33 · 82.1% good
Del Norte County, California
AQI 33 · 81.0% good
What Carter 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 33 means for exposure. Health guidance
- See how Carter County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Carter County with its Oklahoma neighbours before drawing a conclusion about the region. All of Oklahoma
Based on 251 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 Carter County, Oklahoma? ▼
Carter County has a median Air Quality Index (AQI) of 33, rated "Good." 80.9% of monitored days (203 out of 251) had good air quality in 2025.
What is the main pollutant in Carter County? ▼
The primary pollutant in Carter County is Fine Particles (PM2.5), which was the main AQI driver on 251 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Carter County have? ▼
In 2025, Carter County recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 155.
Is the air quality in Carter County getting better or worse? ▼
Air quality in Carter County is improving based on 5-year trends (2020-2025). Best year: 2022 with 254 good days. Worst year: 2021 with 186 good days.
What does AQI 33 mean for health? ▼
Carter County's median AQI of 33 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 Carter County compare to other counties in Oklahoma? ▼
Carter County has 80.9% good air days. Nearby counties in Oklahoma: Adair (59.2% good), Canadian (78.0% good), Cleveland (53.7% good), Comanche (63.8% good), Creek (80.1% good), Dewey (56.6% good).
What is the 90th percentile AQI in Carter County? ▼
The 90th percentile AQI for Carter County is 55, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 155 (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.