Median AQI
51
Moderate
Nevada · County air quality · 2025
Washoe County, Nevada
Median AQI 51 (Moderate). 50.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 51
- Median AQI
- 50.0%
- Good-air days
- 0
- Unhealthy days
- 6%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Washoe County's air is moderate on balance, among the most polluted counties nationally, a median AQI of 51 with 50.0% of 274 monitored days in the Good band, driven mainly by Ozone.
- 51
- median AQI · Moderate
- 50.0%
- days rated Good
- Ozone
- main pollutant
- 6%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 112.
Data updated July 2026
- Good · 137 d · 50.0%
- Moderate · 135 d · 49.3%
- USG · 2 d · 0.7%
How did Washoe County's air break down in 2025?
Across 274 monitored days, 137 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 112 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 274 days monitored. Median AQI: 51 (Moderate).
Insights: Washoe County, Nevada. EPA monitors recorded a median Air Quality Index of 51 across 274 measured days in 2025, earning a Moderate classification and a Moderate health grade. Of those days, 137 (50%) fell in the Good band (AQI 0–50), 135 (49%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 74, while the worst single-day peak hit 112 (USG). Residents averaged about 15.0 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (232 days), PM2.5 (38 days), PM10 (3 days), CO (1 days). Across the 2020–2025 trend window, good days shifted by -56 and the median AQI moved +1 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 112, usg but never Unhealthy. Nearby counties show comparable readings: Carson City (79.3% good, AQI 45); Churchill (81.0% good, AQI 43); Clark (25.6% good, AQI 64); Douglas (90.9% good, AQI 22); Elko (90.8% good, AQI 19); Lyon (83.9% good, AQI 44).
Air Quality Summary
Good Days
50.0%
137 of 274 monitored days
-25.0pp vs 75% target
Max AQI Recorded
112
USG
Health Grade
Moderate
90th-pct AQI 74
Washoe County, Good days share 50.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Washoe 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 274 monitored days across EPA AQI categories.
Good
137
50%
Moderate
135
49%
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 Washoe County.
- Ozone · 232 days · 84.7%
- PM2.5 · 38 days · 13.9%
- PM10 · 3 days · 1.1%
- CO · 1 days · 0.4%
Health Impact Assessment
Moderate
Washoe County's air quality is rated Moderate based on 50.0% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 50.0% of monitored days in 2025, with a median AQI of 51. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 232 of 274 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Washoe County. Best year: 2020 (193 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 193 | 149 | 11 | 11 | 50 | 265 |
| 2021 | 174 | 156 | 16 | 10 | 51 | 333 |
| 2022 | 180 | 176 | 1 | 4 | 51 | 259 |
| 2023 | 191 | 174 | 0 | 0 | 50 | 97 |
| 2024 | 188 | 174 | 4 | 0 | 50 | 119 |
| 2025 | 137 | 135 | 2 | 0 | 51 | 112 |
How does Washoe County compare?
How Washoe County compares
Good-day share worse than US avg
Washoe County 50.0%
Carson City County, Nevada 79.3%
US average 76.5%
Median AQI worse than US avg
Washoe County 51
Carson City County, Nevada 45
US average 38
Unhealthy days / yr about average
Washoe County 0
Carson City County, Nevada 0
US average 0
Other Counties in Nevada
Air quality comparison for nearby counties in Nevada.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Washoe County.
Arapahoe County, Colorado
AQI 51 · 47.3% good
Bibb County, Georgia
AQI 51 · 49.5% good
East Baton Rouge County, Louisiana
AQI 51 · 49.3% good
Eddy County, New Mexico
AQI 51 · 46.9% good
Hillsborough County, Florida
AQI 51 · 49.3% good
Jefferson County, Colorado
AQI 51 · 46.5% good
What Washoe County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 51 means for exposure. Health guidance
- See how Washoe County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Washoe County with its Nevada neighbours before drawing a conclusion about the region. All of Nevada
Based on 274 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 Washoe County, Nevada? ▼
Washoe County has a median Air Quality Index (AQI) of 51, rated "Moderate." 50.0% of monitored days (137 out of 274) had good air quality in 2025.
What is the main pollutant in Washoe County? ▼
The primary pollutant in Washoe County is Ozone (O3), which was the main AQI driver on 232 days (85% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Washoe County have? ▼
In 2025, Washoe County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 112.
Is the air quality in Washoe County getting better or worse? ▼
Air quality in Washoe County is worsening based on 5-year trends (2020-2025). Best year: 2020 with 193 good days. Worst year: 2025 with 137 good days.
What does AQI 51 mean for health? ▼
Washoe County's median AQI of 51 falls in the "Moderate" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Washoe County compare to other counties in Nevada? ▼
Washoe County has 50.0% good air days. Nearby counties in Nevada: Carson City (79.3% good), Churchill (81.0% good), Clark (25.6% good), Douglas (90.9% good), Elko (90.8% good), Lyon (83.9% good).
What is the 90th percentile AQI in Washoe County? ▼
The 90th percentile AQI for Washoe County is 74, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 112 (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.