Median AQI
9
Good
Nebraska · County air quality · 2025
Thomas County, Nebraska
Median AQI 9 (Good). 94.7% of monitored days rated Good, direct from EPA Air Quality System stations.
- 9
- Median AQI
- 94.7%
- Good-air days
- 0
- Unhealthy days
- 88%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Thomas County's air is good on balance, cleaner than most US counties, a median AQI of 9 with 94.7% of 19 monitored days in the Good band, driven mainly by PM2.5.
- 9
- median AQI · Good
- 94.7%
- days rated Good
- PM2.5
- main pollutant
- 88%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 53.
Data updated July 2026
- Good · 18 d · 94.7%
- Moderate · 1 d · 5.3%
How did Thomas County's air break down in 2025?
Across 19 monitored days, 18 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 53 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 19 days monitored. Median AQI: 9 (Good).
Insights: Thomas County, Nebraska. EPA monitors recorded a median Air Quality Index of 9 across 19 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 18 (95%) fell in the Good band (AQI 0–50), 1 (5%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 28, while the worst single-day peak hit 53 (Moderate). Residents averaged about 28.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (19 days). Across the 2020–2025 trend window, good days shifted by -91 and the median AQI moved -5 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 53, moderate but never Unhealthy. Nearby counties show comparable readings: Cass (96.5% good, AQI 20); Douglas (66.8% good, AQI 44); Gage (74.0% good, AQI 36); Hall (80.2% good, AQI 37); Knox (89.3% good, AQI 39); Lancaster (77.7% good, AQI 36).
Air Quality Summary
Good Days
94.7%
18 of 19 monitored days
19.7pp vs 75% target
Max AQI Recorded
53
Moderate
Health Grade
Excellent
90th-pct AQI 28
Thomas County, Good days share 94.7%
National avg
Share of monitored days at AQI 0-50 (Good band).
Thomas 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 19 monitored days across EPA AQI categories.
Good
18
95%
Moderate
1
5%
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 Thomas County.
- PM2.5 · 19 days · 100.0%
Health Impact Assessment
Excellent
Thomas County's air quality is rated Excellent based on 94.7% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 94.7% of monitored days in 2025, with a median AQI of 9. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 19 of 19 monitored days.
5-Year Air Quality Trend
Air quality is stable in Thomas County. Best year: 2021 (111 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 109 | 6 | 0 | 0 | 14 | 74 |
| 2021 | 111 | 6 | 0 | 0 | 19 | 84 |
| 2022 | 85 | 4 | 0 | 0 | 17 | 55 |
| 2024 | 22 | 0 | 0 | 0 | 12 | 36 |
| 2025 | 18 | 1 | 0 | 0 | 9 | 53 |
How does Thomas County compare?
How Thomas County compares
Good-day share better than US avg
Thomas County 94.7%
Cass County, Nebraska 96.5%
US average 76.5%
Median AQI better than US avg
Thomas County 9
Cass County, Nebraska 20
US average 38
Unhealthy days / yr about average
Thomas County 0
Cass County, Nebraska 0
US average 0
Other Counties in Nebraska
Air quality comparison for nearby counties in Nebraska.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Thomas County.
Carroll County, Virginia
AQI 9 · 100.0% good
Dakota County, Minnesota
AQI 9 · 93.4% good
Roosevelt County, Montana
AQI 9 · 100.0% good
Sonoma County, California
AQI 9 · 100.0% good
Catron County, New Mexico
AQI 8 · 100.0% good
Kenai Peninsula County, Alaska
AQI 8 · 100.0% good
What Thomas 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 9 means for exposure. Health guidance
- See how Thomas County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Thomas County with its Nebraska neighbours before drawing a conclusion about the region. All of Nebraska
Based on 19 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 Thomas County, Nebraska? ▼
Thomas County has a median Air Quality Index (AQI) of 9, rated "Good." 94.7% of monitored days (18 out of 19) had good air quality in 2025.
What is the main pollutant in Thomas County? ▼
The primary pollutant in Thomas County is Fine Particles (PM2.5), which was the main AQI driver on 19 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Thomas County have? ▼
In 2025, Thomas County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 53.
Is the air quality in Thomas County getting better or worse? ▼
Air quality in Thomas County is stable based on 5-year trends (2020-2025). Best year: 2021 with 111 good days. Worst year: 2025 with 18 good days.
What does AQI 9 mean for health? ▼
Thomas County's median AQI of 9 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 Thomas County compare to other counties in Nebraska? ▼
Thomas County has 94.7% good air days. Nearby counties in Nebraska: Cass (96.5% good), Douglas (66.8% good), Gage (74.0% good), Hall (80.2% good), Knox (89.3% good), Lancaster (77.7% good).
What is the 90th percentile AQI in Thomas County? ▼
The 90th percentile AQI for Thomas County is 28, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 53 (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.