Median AQI
29
Good
Nebraska · County air quality · 2025
Washington County, Nebraska
Median AQI 29 (Good). 84.3% of monitored days rated Good, direct from EPA Air Quality System stations.
- 29
- Median AQI
- 84.3%
- Good-air days
- 0
- Unhealthy days
- 63%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Washington County's air is good on balance, cleaner than the median US county, a median AQI of 29 with 84.3% of 248 monitored days in the Good band, driven mainly by PM2.5.
- 29
- median AQI · Good
- 84.3%
- days rated Good
- PM2.5
- main pollutant
- 63%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 132.
Data updated July 2026
- Good · 209 d · 84.3%
- Moderate · 38 d · 15.3%
- USG · 1 d · 0.4%
How did Washington County's air break down in 2025?
Across 248 monitored days, 209 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 132 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 248 days monitored. Median AQI: 29 (Good).
Insights: Washington County, Nebraska. EPA monitors recorded a median Air Quality Index of 29 across 248 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 209 (84%) fell in the Good band (AQI 0–50), 38 (15%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 56, while the worst single-day peak hit 132 (USG). Residents averaged about 25.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (248 days). Across the 2020–2025 trend window, good days shifted by +116 and the median AQI moved -2 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 132, usg 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
84.3%
209 of 248 monitored days
9.3pp vs 75% target
Max AQI Recorded
132
USG
Health Grade
Good
90th-pct AQI 56
Washington County, Good days share 84.3%
National avg
Share of monitored days at AQI 0-50 (Good band).
Washington 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 248 monitored days across EPA AQI categories.
Good
209
84%
Moderate
38
15%
USG
1
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 Washington County.
- PM2.5 · 248 days · 100.0%
Health Impact Assessment
Good
Washington County's air quality is rated Good based on 84.3% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 84.3% of monitored days in 2025, with a median AQI of 29. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 248 of 248 monitored days.
5-Year Air Quality Trend
Air quality is stable in Washington County. Best year: 2022 (280 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 93 | 17 | 0 | 0 | 31 | 75 |
| 2021 | 83 | 25 | 1 | 0 | 37 | 125 |
| 2022 | 280 | 19 | 0 | 0 | 19 | 64 |
| 2023 | 258 | 98 | 3 | 1 | 33 | 154 |
| 2024 | 268 | 86 | 0 | 0 | 34 | 81 |
| 2025 | 209 | 38 | 1 | 0 | 29 | 132 |
How does Washington County compare?
How Washington County compares
Good-day share better than US avg
Washington County 84.3%
Cass County, Nebraska 96.5%
US average 76.5%
Median AQI better than US avg
Washington County 29
Cass County, Nebraska 20
US average 38
Unhealthy days / yr about average
Washington 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 Washington County.
Bayamon County, Puerto Rico
AQI 29 · 88.5% good
Fajardo County, Puerto Rico
AQI 29 · 85.7% good
Grant County, Oklahoma
AQI 29 · 90.0% good
Jackson County, Wisconsin
AQI 29 · 76.0% good
Nez Perce County, Idaho
AQI 29 · 84.0% good
Roane County, Tennessee
AQI 29 · 84.1% good
What Washington 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 29 means for exposure. Health guidance
- See how Washington County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Washington County with its Nebraska neighbours before drawing a conclusion about the region. All of Nebraska
Based on 248 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 Washington County, Nebraska? ▼
Washington County has a median Air Quality Index (AQI) of 29, rated "Good." 84.3% of monitored days (209 out of 248) had good air quality in 2025.
What is the main pollutant in Washington County? ▼
The primary pollutant in Washington County is Fine Particles (PM2.5), which was the main AQI driver on 248 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Washington County have? ▼
In 2025, Washington County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 132.
Is the air quality in Washington County getting better or worse? ▼
Air quality in Washington County is stable based on 5-year trends (2020-2025). Best year: 2022 with 280 good days. Worst year: 2021 with 83 good days.
What does AQI 29 mean for health? ▼
Washington County's median AQI of 29 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 Washington County compare to other counties in Nebraska? ▼
Washington County has 84.3% 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 Washington County? ▼
The 90th percentile AQI for Washington County is 56, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 132 (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.