Median AQI
38
Good
Oklahoma · County air quality · 2025
Kay County, Oklahoma
Median AQI 38 (Good). 68.4% of monitored days rated Good, direct from EPA Air Quality System stations.
- 38
- Median AQI
- 68.4%
- Good-air days
- 0
- Unhealthy days
- 28%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Kay County's air is good on balance, more polluted than the median US county, a median AQI of 38 with 68.4% of 269 monitored days in the Good band, driven mainly by PM2.5.
- 38
- median AQI · Good
- 68.4%
- days rated Good
- PM2.5
- main pollutant
- 28%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 141.
Data updated July 2026
- Good · 184 d · 68.4%
- Moderate · 83 d · 30.9%
- USG · 2 d · 0.7%
How did Kay County's air break down in 2025?
Across 269 monitored days, 184 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 141 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 269 days monitored. Median AQI: 38 (Good).
Insights: Kay County, Oklahoma. EPA monitors recorded a median Air Quality Index of 38 across 269 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 184 (68%) fell in the Good band (AQI 0–50), 83 (31%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 58, while the worst single-day peak hit 141 (USG). Residents averaged about 20.5 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (269 days). Across the 2020–2025 trend window, good days shifted by +13 and the median AQI moved -13 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 141, 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
68.4%
184 of 269 monitored days
-6.6pp vs 75% target
Max AQI Recorded
141
USG
Health Grade
Moderate
90th-pct AQI 58
Kay County, Good days share 68.4%
National avg
Share of monitored days at AQI 0-50 (Good band).
Kay 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 269 monitored days across EPA AQI categories.
Good
184
68%
Moderate
83
31%
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 Kay County.
- PM2.5 · 269 days · 100.0%
Health Impact Assessment
Moderate
Kay County's air quality is rated Moderate based on 68.4% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 68.4% of monitored days in 2025, with a median AQI of 38. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 269 of 269 monitored days.
5-Year Air Quality Trend
Air quality is improving in Kay County. Best year: 2022 (225 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 171 | 193 | 2 | 0 | 51 | 113 |
| 2021 | 167 | 178 | 8 | 1 | 52 | 168 |
| 2022 | 225 | 136 | 0 | 0 | 43 | 93 |
| 2023 | 172 | 162 | 1 | 0 | 49 | 122 |
| 2024 | 223 | 128 | 4 | 1 | 42 | 193 |
| 2025 | 184 | 83 | 2 | 0 | 38 | 141 |
How does Kay County compare?
How Kay County compares
Good-day share worse than US avg
Kay County 68.4%
Adair County, Oklahoma 59.2%
US average 76.5%
Median AQI about average
Kay County 38
Adair County, Oklahoma 45
US average 38
Unhealthy days / yr about average
Kay 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 Kay County.
Adams County, Illinois
AQI 38 · 94.4% good
Anoka County, Minnesota
AQI 38 · 82.1% good
Atlantic County, New Jersey
AQI 38 · 79.6% good
Avery County, North Carolina
AQI 38 · 93.9% good
Barnstable County, Massachusetts
AQI 38 · 92.5% good
Bay County, Michigan
AQI 38 · 71.8% good
What Kay 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 38 means for exposure. Health guidance
- See how Kay County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Kay County with its Oklahoma neighbours before drawing a conclusion about the region. All of Oklahoma
Based on 269 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 Kay County, Oklahoma? ▼
Kay County has a median Air Quality Index (AQI) of 38, rated "Good." 68.4% of monitored days (184 out of 269) had good air quality in 2025.
What is the main pollutant in Kay County? ▼
The primary pollutant in Kay County is Fine Particles (PM2.5), which was the main AQI driver on 269 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Kay County have? ▼
In 2025, Kay County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 141.
Is the air quality in Kay County getting better or worse? ▼
Air quality in Kay County is improving based on 5-year trends (2020-2025). Best year: 2022 with 225 good days. Worst year: 2021 with 167 good days.
What does AQI 38 mean for health? ▼
Kay County's median AQI of 38 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 Kay County compare to other counties in Oklahoma? ▼
Kay County has 68.4% 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 Kay County? ▼
The 90th percentile AQI for Kay County is 58, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 141 (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.