Median AQI
48
Good
Colorado · County air quality · 2025
Chaffee County, Colorado
Median AQI 48 (Good). 66.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 48
- Median AQI
- 66.0%
- Good-air days
- 0
- Unhealthy days
- 24%
- Cleaner than US counties
Chaffee County's 2025 annual median AQI is 48 (Good), with 66.0% Good days
According to the U.S. EPA Air Quality System, Chaffee County, Colorado posted a 2025 median AQI of 48 (Good) across 103 monitored days, with 66.0% 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
- Chaffee County's 66.0% Good-day share places it cleaner than 24% of US counties in 2025.
- Closest median-AQI peer
- Adair County (55.8% Good, median AQI 48) is the closest nationwide median-AQI peer to Chaffee County.
- 2021–2025 trend
- Chaffee County's floor-qualifying Good-day share is improving from 2021 to 2025 (42.0% → 66.0%).
- Median AQI
- Median AQI: 48
The verdict
According to EPA Air Quality System monitoring data, Chaffee County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 48 with 66.0% of 103 monitored days in the Good band, driven mainly by Ozone.
- 48
- median AQI · Good
- 66.0%
- days rated Good
- Ozone
- main pollutant
- 24%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 108.
Annual release change
What changed in the 2025 EPA annual release
- Chaffee County's Good-day share rose from 46.0% to 66.0% between the 2024 and 2025 EPA annual releases, a change of +20.1 percentage points.
- Chaffee County's median AQI fell from 51 to 48 between the 2024 and 2025 EPA annual releases, a change of -3 points.
Data updated August 2026
- Good · 68 d · 66.0%
- Moderate · 30 d · 29.1%
- USG · 5 d · 4.9%
How did Chaffee County's air break down in 2025?
Across 103 monitored days, 68 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 108 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 103 days monitored. Median AQI: 48 (Good).
Insights: Chaffee County, Colorado. EPA monitors recorded a median Air Quality Index of 48 across 103 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 68 (66%) fell in the Good band (AQI 0–50), 30 (29%) registered Moderate readings, and 5 (5%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 84, while the worst single-day peak hit 108 (USG). Residents averaged about 19.8 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (103 days). Across the 2021–2025 trend window, the share of monitored days rated Good shifted by +24.1 points (measured against 112 monitored days in 2021 and 103 in 2025, so raw day counts are not comparable) and the median AQI moved -10 points, placing the multi-year trajectory at improving. The worst single reading over the 2021–2025 window was AQI 108, 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); Archuleta (83.0% good, AQI 34); Boulder (58.4% good, AQI 48); Clear Creek (67.9% good, AQI 48).
Air Quality Summary
Good Days
66.0%
68 of 103 monitored days
-9.0pp vs 75% target
Max AQI Recorded
108
USG
Health Grade
Moderate
90th-pct AQI 84
Chaffee County, Good days share 66.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Chaffee 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 103 monitored days across EPA AQI categories.
Good
68
66%
Moderate
30
29%
USG
5
5%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Chaffee County.
- Ozone · 103 days · 100.0%
Health Impact Assessment
Moderate
Chaffee County's air quality is rated Moderate based on 66.0% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 66.0% of monitored days in 2025, with a median AQI of 48. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 103 of 103 monitored days.
5-Year Air Quality Trend
Air quality is improving in Chaffee County. Highest Good-day share: 2025 (66.0%, 68 of 103 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 37 | 29 | 3 | 0 | 50 | 101 |
| 2021 | 47 | 59 | 6 | 0 | 58 | 119 |
| 2022 | 98 | 57 | 1 | 0 | 49 | 119 |
| 2023 | 66 | 96 | 4 | 0 | 58 | 115 |
| 2024 | 74 | 82 | 5 | 0 | 51 | 112 |
| 2025 | 68 | 30 | 5 | 0 | 48 | 108 |
How does Chaffee County compare?
How Chaffee County compares
Good-day share worse than US avg
Chaffee County 66.0%
Adair County, Oklahoma 55.8%
US average 76.0%
Median AQI worse than US avg
Chaffee County 48
Adair County, Oklahoma 48
US average 39
Unhealthy days / yr better than US avg
Chaffee County 0
Adair County, Oklahoma 2
US average 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Chaffee County (48), not geographic neighbors.
Adair County, Oklahoma
Median AQI 48 · 55.8% Good-day share
Arapahoe County, Colorado
Median AQI 48 · 58.1% Good-day share
Arkansas County, Arkansas
Median AQI 48 · 52.9% Good-day share
Ashley County, Arkansas
Median AQI 48 · 55.7% Good-day share
Boulder County, Colorado
Median AQI 48 · 58.4% Good-day share
Bowie County, Texas
Median AQI 48 · 55.0% 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).
Bell County, Texas
66.0% Good-day share · median AQI 45
Cache County, Utah
66.0% Good-day share · median AQI 44
District of Columbia County, District of Columbia
66.0% Good-day share · median AQI 45
St. Joseph County, Indiana
66.0% Good-day share · median AQI 43
Yavapai County, Arizona
65.9% Good-day share · median AQI 47
Champaign County, Illinois
65.8% Good-day share · median AQI 43
Colorado counties on the map
Geographic containment only, other monitored counties in Colorado, independent of AQI or pollutant match.
What Chaffee 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 48 means for exposure. Health guidance
- See how Chaffee County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Chaffee County with its Colorado neighbours before drawing a conclusion about the region. All of Colorado
Based on 103 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 Chaffee County, Colorado? ▼
Chaffee County has a median Air Quality Index (AQI) of 48, rated "Good." 66.0% of monitored days (68 out of 103) had good air quality in 2025.
What is the main pollutant in Chaffee County? ▼
The primary pollutant in Chaffee County is Ozone (O3), which was the main AQI driver on 103 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Chaffee County have? ▼
In 2025, Chaffee County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 108.
Is the air quality in Chaffee County getting better or worse? ▼
Air quality in Chaffee County is improving across floor-qualifying years (2021-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2025 at 66.0% (68 of 103 days). Lowest qualifying Good-day share: 2023 at 39.8% (66 of 166 days).
What does AQI 48 mean for health? ▼
Chaffee County's median AQI of 48 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Chaffee County compare to other counties in Colorado? ▼
Chaffee County has 66.0% good air days. Nearby counties in Colorado: Adams (55.1% good), Alamosa (91.5% good), Arapahoe (58.1% good), Archuleta (83.0% good), Boulder (58.4% good), Clear Creek (67.9% good).
What is the 90th percentile AQI in Chaffee County? ▼
The 90th percentile AQI for Chaffee County is 84, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 108 (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 Chaffee 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.