Median AQI
23
Good
Colorado · County air quality · 2025
Routt County, Colorado
Median AQI 23 (Good). 91.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 23
- Median AQI
- 91.6%
- Good-air days
- 0
- Unhealthy days
- 79%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Routt County's air is good on balance, cleaner than most US counties, a median AQI of 23 with 91.6% of 273 monitored days in the Good band, driven mainly by PM2.5.
- 23
- median AQI · Good
- 91.6%
- days rated Good
- PM2.5
- main pollutant
- 79%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 87.
Data updated July 2026
- Good · 250 d · 91.6%
- Moderate · 23 d · 8.4%
How did Routt County's air break down in 2025?
Across 273 monitored days, 250 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 87 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 273 days monitored. Median AQI: 23 (Good).
Insights: Routt County, Colorado. EPA monitors recorded a median Air Quality Index of 23 across 273 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 250 (92%) fell in the Good band (AQI 0–50), 23 (8%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 48, while the worst single-day peak hit 87 (Moderate). Residents averaged about 27.5 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (255 days), PM10 (18 days). Across the 2020–2025 trend window, good days shifted by -103 and the median AQI moved +9 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 87, moderate but never Unhealthy. Nearby counties show comparable readings: Adams (50.2% good, AQI 50); Alamosa (90.8% good, AQI 24); Arapahoe (47.3% good, AQI 51); Archuleta (79.5% good, AQI 32); Boulder (50.9% good, AQI 50); Clear Creek (64.4% good, AQI 48).
Air Quality Summary
Good Days
91.6%
250 of 273 monitored days
16.6pp vs 75% target
Max AQI Recorded
87
Moderate
Health Grade
Excellent
90th-pct AQI 48
Routt County, Good days share 91.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
Routt 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 273 monitored days across EPA AQI categories.
Good
250
92%
Moderate
23
8%
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 Routt County.
- PM2.5 · 255 days · 93.4%
- PM10 · 18 days · 6.6%
Health Impact Assessment
Excellent
Routt County's air quality is rated Excellent based on 91.6% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 91.6% of monitored days in 2025, with a median AQI of 23. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 255 of 273 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Routt County. Best year: 2024 (364 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 353 | 5 | 0 | 0 | 14 | 68 |
| 2021 | 347 | 7 | 0 | 0 | 15 | 68 |
| 2022 | 356 | 0 | 0 | 0 | 13 | 43 |
| 2023 | 348 | 5 | 0 | 0 | 13 | 58 |
| 2024 | 364 | 1 | 0 | 0 | 12 | 53 |
| 2025 | 250 | 23 | 0 | 0 | 23 | 87 |
How does Routt County compare?
How Routt County compares
Good-day share better than US avg
Routt County 91.6%
Adams County, Colorado 50.2%
US average 76.5%
Median AQI better than US avg
Routt County 23
Adams County, Colorado 50
US average 38
Unhealthy days / yr about average
Routt County 0
Adams County, Colorado 0
US average 0
Other Counties in Colorado
Air quality comparison for nearby counties in Colorado.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Routt County.
Lawrence County, Alabama
AQI 23 · 100.0% good
Lemhi County, Idaho
AQI 23 · 69.1% good
Wallowa County, Oregon
AQI 23 · 91.2% good
Wasco County, Oregon
AQI 23 · 92.8% good
Alamosa County, Colorado
AQI 24 · 90.8% good
Anchorage County, Alaska
AQI 24 · 80.8% good
What Routt 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 23 means for exposure. Health guidance
- See how Routt County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Routt County with its Colorado neighbours before drawing a conclusion about the region. All of Colorado
Based on 273 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 Routt County, Colorado? ▼
Routt County has a median Air Quality Index (AQI) of 23, rated "Good." 91.6% of monitored days (250 out of 273) had good air quality in 2025.
What is the main pollutant in Routt County? ▼
The primary pollutant in Routt County is Fine Particles (PM2.5), which was the main AQI driver on 255 days (93% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Routt County have? ▼
In 2025, Routt County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 87.
Is the air quality in Routt County getting better or worse? ▼
Air quality in Routt County is worsening based on 5-year trends (2020-2025). Best year: 2024 with 364 good days. Worst year: 2025 with 250 good days.
What does AQI 23 mean for health? ▼
Routt County's median AQI of 23 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 Routt County compare to other counties in Colorado? ▼
Routt County has 91.6% good air days. Nearby counties in Colorado: Adams (50.2% good), Alamosa (90.8% good), Arapahoe (47.3% good), Archuleta (79.5% good), Boulder (50.9% good), Clear Creek (64.4% good).
What is the 90th percentile AQI in Routt County? ▼
The 90th percentile AQI for Routt County is 48, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 87 (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.