Median AQI
34
Good
Colorado · County air quality · 2025
Archuleta County, Colorado
Median AQI 34 (Good). 83.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 34
- Median AQI
- 83.0%
- Good-air days
- 0
- Unhealthy days
- 64%
- Cleaner than US counties
Archuleta County's 2025 annual median AQI is 34 (Good), with 83.0% Good days
According to the U.S. EPA Air Quality System, Archuleta County, Colorado posted a 2025 median AQI of 34 (Good) across 364 monitored days, with 83.0% rated Good and 0 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Archuleta County's 83.0% Good-day share places it cleaner than 64% of US counties in 2025.
- Closest median-AQI peer
- Androscoggin County (85.2% Good, median AQI 34) is the closest nationwide median-AQI peer to Archuleta County.
- 2020–2025 trend
- Archuleta County's floor-qualifying Good-day share is improving from 2020 to 2025 (82.7% → 83.0%).
- Median AQI
- Median AQI: 34
The verdict
According to EPA Air Quality System monitoring data, Archuleta County's air is good on balance, cleaner than the median US county, a median AQI of 34 with 83.0% of 364 monitored days in the Good band, driven mainly by Ozone.
- 34
- median AQI · Good
- 83.0%
- days rated Good
- Ozone
- main pollutant
- 64%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 115.
Annual release change
What changed in the 2025 EPA annual release
- Archuleta County's Good-day share fell from 95.4% to 83.0% between the 2024 and 2025 EPA annual releases, a change of -12.4 percentage points.
- Archuleta County's peak single-day AQI rose from 80 to 115 between the 2024 and 2025 EPA annual releases, a change of +35 points.
Data updated August 2026
- Good · 302 d · 83.0%
- Moderate · 60 d · 16.5%
- USG · 2 d · 0.5%
How did Archuleta County's air break down in 2025?
Across 364 monitored days, 302 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 115 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 364 days monitored. Median AQI: 34 (Good).
Insights: Archuleta County, Colorado. EPA monitors recorded a median Air Quality Index of 34 across 364 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 302 (83%) fell in the Good band (AQI 0–50), 60 (16%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 115 (USG). Residents averaged about 24.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (186 days), PM2.5 (149 days), PM10 (29 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by +0.2 points and the median AQI moved -9 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 115, usg but never Unhealthy. Nearby counties show comparable readings: Adams (55.1% good, AQI 49); Alamosa (91.5% good, AQI 25); Arapahoe (58.1% good, AQI 48); Boulder (58.4% good, AQI 48); Chaffee (66.0% good, AQI 48); Clear Creek (67.9% good, AQI 48).
Air Quality Summary
Good Days
83.0%
302 of 364 monitored days
8.0pp vs 75% target
Max AQI Recorded
115
USG
Health Grade
Good
90th-pct AQI 61
Archuleta County, Good days share 83.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Archuleta 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 364 monitored days across EPA AQI categories.
Good
302
83%
Moderate
60
16%
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 Archuleta County.
- Ozone · 186 days · 51.1%
- PM2.5 · 149 days · 40.9%
- PM10 · 29 days · 8.0%
Health Impact Assessment
Good
Archuleta County's air quality is rated Good based on 83.0% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 83.0% of monitored days in 2025, with a median AQI of 34. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 186 of 364 monitored days.
5-Year Air Quality Trend
Air quality is improving in Archuleta County. Highest Good-day share: 2023 (95.6%, 349 of 365 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 302 | 63 | 0 | 0 | 43 | 93 |
| 2021 | 269 | 96 | 0 | 0 | 45 | 93 |
| 2022 | 313 | 48 | 3 | 0 | 42 | 227 |
| 2023 | 349 | 15 | 1 | 0 | 35 | 120 |
| 2024 | 349 | 17 | 0 | 0 | 32 | 80 |
| 2025 | 302 | 60 | 2 | 0 | 34 | 115 |
How does Archuleta County compare?
How Archuleta County compares
Good-day share better than typical
Archuleta County 83.0%
Androscoggin County, Maine 85.2%
Typical US county 76.0%
Median AQI better than typical
Archuleta County 34
Androscoggin County, Maine 34
Typical US county 39
Unhealthy days / yr better than typical
Archuleta County 0
Androscoggin County, Maine 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Archuleta County (34), not geographic neighbors.
Androscoggin County, Maine
Median AQI 34 · 85.2% Good-day share
Bristol City County, Virginia
Median AQI 34 · 78.0% Good-day share
Brown County, Indiana
Median AQI 34 · 95.9% Good-day share
Clark County, Arkansas
Median AQI 34 · 96.7% Good-day share
Clay County, South Dakota
Median AQI 34 · 87.8% Good-day share
Dawson County, Georgia
Median AQI 34 · 95.1% Good-day share
Same primary pollutant: Ozone
Ozone led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
San Miguel County, Colorado
83.0% Good-day share · median AQI 36
Wood County, West Virginia
82.9% Good-day share · median AQI 39
Harrison County, Iowa
83.0% Good-day share · median AQI 39
Montgomery County, Maryland
83.1% Good-day share · median AQI 39
Geauga County, Ohio
82.9% Good-day share · median AQI 42
Clinton County, Ohio
83.1% Good-day share · median AQI 41
Colorado counties on the map
Geographic containment only, other monitored counties in Colorado, independent of AQI or pollutant match.
What Archuleta 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 34 means for exposure. Health guidance
- See how Archuleta County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Archuleta County with its Colorado neighbours before drawing a conclusion about the region. All of Colorado
Based on 364 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Archuleta County, Colorado? ▼
Archuleta County has a median Air Quality Index (AQI) of 34, rated "Good." 83.0% of monitored days (302 out of 364) had good air quality in 2025.
What is the main pollutant in Archuleta County? ▼
The primary pollutant in Archuleta County is Ozone (O3), which was the main AQI driver on 186 days (51% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Archuleta County have? ▼
In 2025, Archuleta County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 115.
Is the air quality in Archuleta County getting better or worse? ▼
Air quality in Archuleta County is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2023 at 95.6% (349 of 365 days). Lowest qualifying Good-day share: 2021 at 73.7% (269 of 365 days).
What does AQI 34 mean for health? ▼
Archuleta County's median AQI of 34 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Archuleta County compare to other counties in Colorado? ▼
Archuleta County has 83.0% good air days. Nearby counties in Colorado: Adams (55.1% good), Alamosa (91.5% good), Arapahoe (58.1% good), Boulder (58.4% good), Chaffee (66.0% good), Clear Creek (67.9% good).
What is the 90th percentile AQI in Archuleta County? ▼
The 90th percentile AQI for Archuleta County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 115 (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. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Archuleta County, Colorado · 2020–2025
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Every figure on PlainAirData 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.