Median AQI
46
Good
Colorado · County air quality · 2025
Montezuma County, Colorado
Median AQI 46 (Good). 72.9% of monitored days rated Good, direct from EPA Air Quality System stations.
- 46
- Median AQI
- 72.9%
- Good-air days
- 0
- Unhealthy days
- 37%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Montezuma County's air is good on balance, more polluted than the median US county, a median AQI of 46 with 72.9% of 273 monitored days in the Good band, driven mainly by Ozone.
- 46
- median AQI · Good
- 72.9%
- days rated Good
- Ozone
- main pollutant
- 37%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 101.
Data updated July 2026
- Good · 199 d · 72.9%
- Moderate · 73 d · 26.7%
- USG · 1 d · 0.4%
How did Montezuma County's air break down in 2025?
Across 273 monitored days, 199 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 101 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 273 days monitored. Median AQI: 46 (Good).
Insights: Montezuma County, Colorado. EPA monitors recorded a median Air Quality Index of 46 across 273 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 199 (73%) fell in the Good band (AQI 0–50), 73 (27%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 64, while the worst single-day peak hit 101 (USG). Residents averaged about 21.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (273 days). Across the 2020–2025 trend window, good days shifted by -102 and the median AQI moved +2 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 101, usg 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
72.9%
199 of 273 monitored days
-2.1pp vs 75% target
Max AQI Recorded
101
USG
Health Grade
Moderate
90th-pct AQI 64
Montezuma County, Good days share 72.9%
National avg
Share of monitored days at AQI 0-50 (Good band).
Montezuma 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
199
73%
Moderate
73
27%
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 Montezuma County.
- Ozone · 273 days · 100.0%
Health Impact Assessment
Moderate
Montezuma County's air quality is rated Moderate based on 72.9% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 72.9% of monitored days in 2025, with a median AQI of 46. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 273 of 273 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Montezuma County. Best year: 2020 (301 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 301 | 63 | 2 | 0 | 44 | 126 |
| 2021 | 280 | 83 | 2 | 0 | 44 | 115 |
| 2022 | 300 | 65 | 0 | 0 | 44 | 87 |
| 2023 | 291 | 74 | 0 | 0 | 44 | 80 |
| 2024 | 262 | 103 | 1 | 0 | 45 | 101 |
| 2025 | 199 | 73 | 1 | 0 | 46 | 101 |
How does Montezuma County compare?
How Montezuma County compares
Good-day share worse than US avg
Montezuma County 72.9%
Adams County, Colorado 50.2%
US average 76.5%
Median AQI worse than US avg
Montezuma County 46
Adams County, Colorado 50
US average 38
Unhealthy days / yr about average
Montezuma 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 Montezuma County.
Bay County, Florida
AQI 46 · 60.6% good
Blount County, Tennessee
AQI 46 · 69.6% good
Cache County, Utah
AQI 46 · 61.2% good
Chesterfield County, South Carolina
AQI 46 · 61.2% good
Clark County, Indiana
AQI 46 · 59.7% good
Clark County, Ohio
AQI 46 · 59.4% good
What Montezuma 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 46 means for exposure. Health guidance
- See how Montezuma County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Montezuma 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 Montezuma County, Colorado? ▼
Montezuma County has a median Air Quality Index (AQI) of 46, rated "Good." 72.9% of monitored days (199 out of 273) had good air quality in 2025.
What is the main pollutant in Montezuma County? ▼
The primary pollutant in Montezuma County is Ozone (O3), which was the main AQI driver on 273 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Montezuma County have? ▼
In 2025, Montezuma County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 101.
Is the air quality in Montezuma County getting better or worse? ▼
Air quality in Montezuma County is worsening based on 5-year trends (2020-2025). Best year: 2020 with 301 good days. Worst year: 2025 with 199 good days.
What does AQI 46 mean for health? ▼
Montezuma County's median AQI of 46 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 Montezuma County compare to other counties in Colorado? ▼
Montezuma County has 72.9% 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 Montezuma County? ▼
The 90th percentile AQI for Montezuma County is 64, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 101 (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.