Metro area air quality · 2024

Boulder, CO

Median AQI 49 (Good). 57.9% of monitored days rated Good across this metro's EPA monitoring network.

49
Median AQI
57.9%
Good-air days
1
Unhealthy days
23%
Cleaner than US metros

Aggregated from EPA Air Quality System (2024), 366 monitored days. EPA AQS → · NOAA →

Insights: Boulder, CO metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 49 over 366 measured days in 2024, which corresponds to a Good band and a Moderate metro-wide health grade. The monitored-day split lands at 212 Good days (58%), 144 Moderate (39%), and 9 Unhealthy-for-Sensitive-Groups (2%). The 90th-percentile AQI finished at 77 while the highest single-day reading hit 154 (Unhealthy). Metro residents averaged roughly 17.4 clean-air days per 30-day window across the reporting year.

Across the 2020–2024 trend window, good days shifted by +39 and the median AQI moved -2 points, which classifies the multi-year trajectory as improving. The metro recorded 1 unhealthy-or-worse days combined, on those days the EPA recommends that sensitive groups limit prolonged outdoor exertion, and many schools and athletic programs adjust outdoor activity accordingly. Metros with comparable AQI profiles include Carlsbad-Artesia, NM (51.4% good, AQI 49); Colorado Springs, CO (55.2% good, AQI 49); Columbus, GA-AL (52.5% good, AQI 49).

Air Quality Summary

Median AQI

49

Good

Good Days

57.9%

212 of 366 days

Max AQI

154

Unhealthy

Health Grade

Moderate

90th pct: 77

AQI Day Breakdown (2024)

Distribution of 366 monitored days across EPA AQI categories.

Good

212

58%

Moderate

144

39%

USG

9

2%

Unhealthy

1

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Boulder, CO metro area's air quality is rated Moderate based on 57.9% good air days. There were 1 unhealthy days in 2024 when outdoor activity should be limited.

Air quality is acceptable most days, but 9 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 154. Sensitive groups should monitor real-time conditions at AirNow.gov.

How does the Boulder, CO metro compare?

How Boulder, CO compares

Good-day share worse than US avg
Boulder, CO 57.9%
Carlsbad-Artesia, NM 51.4%
US average 70.2%
Median AQI worse than US avg
Boulder, CO 49
Carlsbad-Artesia, NM 49
US average 41
Unhealthy days / yr about average
Boulder, CO 1
Carlsbad-Artesia, NM 3
US average 1

5-Year Air Quality Trend

Air quality is improving in the Boulder, CO metro. Best year: 2022 (224 good days).

Year Good Moderate Unhealthy Median AQI
2020 173 172 2 51
2021 154 176 3 52
2022 224 134 0 47
2023 192 167 2 50
2024 212 144 1 49

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Boulder, CO.

Carlsbad-Artesia, NM

AQI 49 · 51.4% good

49

Colorado Springs, CO

AQI 49 · 55.2% good

49

Columbus, GA-AL

AQI 49 · 52.5% good

49

El Dorado, AR

AQI 49 · 51.2% good

49

Glenwood Springs, CO

AQI 49 · 57.9% good

49

Greenville-Anderson-Mauldin, SC

AQI 49 · 53.7% good

49

More Air Quality Data

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Worst Air Quality

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All Metro Areas

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Best and Worst City Air

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Air Quality Guides

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Understanding AQI

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Best & Worst City Air Quality

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Health Effects of Air Pollution

How PM2.5 and ozone exposure affects respiratory and cardiovascular health.

Frequently Asked Questions

What is the air quality in the Boulder, CO metro area? ▼
The Boulder, CO metro area has a median Air Quality Index (AQI) of 49, rated "Good." 57.9% of monitored days (212 out of 366) had good air quality in 2024.
How many unhealthy air days does Boulder, CO have? ▼
In 2024, the Boulder, CO metro area recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 154.
Is air quality in Boulder, CO getting better or worse? ▼
Air quality in the Boulder, CO metro is improving based on 5-year trends (2020-2024). Best year: 2022 with 224 good days. Worst year: 2021 with 154 good days.
What does AQI 49 mean for health? ▼
An AQI of 49 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
What is the 90th percentile AQI for Boulder, CO? ▼
The 90th percentile AQI for the Boulder, CO metro area is 77, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 154 (Unhealthy).
How does Boulder, CO compare to other metro areas? ▼
The Boulder, CO metro has 57.9% good air days. Similar metros: Carlsbad-Artesia, NM (51.4% good), Colorado Springs, CO (55.2% good), Columbus, GA-AL (52.5% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2024. The AQS collects ambient air monitoring data from state, local, and tribal monitoring agencies across the United States.

Metrics: Air Quality Index (AQI) is calculated using EPA-standard breakpoints for six criteria pollutants: PM2.5, PM10, Ozone, NO2, CO, and SO2. Median AQI, max AQI, and 90th percentile AQI are computed from daily measurements. Good days percentage reflects days with AQI 0–50.

Coverage: 501 metro areas (Core Based Statistical Areas). Only metros with active monitoring stations are included. Unmonitored areas are not represented.

Read our methodology , how this data is sourced, computed, and verified.

Source: U.S. EPA, AirNow / AQS Air Quality Index readings and pollutant concentrations · 2025