Metro area air quality · 2025

Missoula, MT

Median AQI 38 (Good). 83.4% of monitored days rated Good across this metro's EPA monitoring network.

38
Median AQI
83.4%
Good-air days
0
Unhealthy days
73%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 181 monitored days. EPA AQS →

The verdict

The Missoula, MT metro runs good on the EPA scale, cleaner than the median US metro, a median AQI of 38 with 83.4% of 181 monitored days in the Good band.

38
median AQI · Good
83.4%
days rated Good
73%
cleaner than US metros
82
worst single reading

No day crossed into the Unhealthy tier across the metro's monitors in 2025.

Insights: Missoula, MT metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 38 over 181 measured days in 2025, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 151 Good days (83%), 30 Moderate (17%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 56 while the highest single-day reading hit 82 (Moderate). Metro residents averaged roughly 25.0 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -4 and the median AQI moved -16 points, which classifies the multi-year trajectory as improving. The metro avoided any Unhealthy-tier days entirely, an outcome that typically reflects favorable wind patterns, lower industrial density, or effective regional emission controls. Metros with comparable AQI profiles include Appleton, WI (78.5% good, AQI 38); Atlantic City-Hammonton, NJ (79.6% good, AQI 38); Barnstable Town, MA (92.5% good, AQI 38).

Air Quality Summary

Median AQI

38

Good

Good Days

83.4%

151 of 181 days

Max AQI

82

Moderate

Health Grade

Good

90th pct: 56

AQI Day Breakdown (2025)

Distribution of 181 monitored days across EPA AQI categories.

Good

151

83%

Moderate

30

17%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Missoula, MT metro area's air quality is rated Good based on 83.4% good air days. No unhealthy air days were recorded in 2025.

Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.

How does the Missoula, MT metro compare?

How Missoula, MT compares

Good-day share better than US avg
Missoula, MT 83.4%
Appleton, WI 78.5%
US average 71.3%
Median AQI better than US avg
Missoula, MT 38
Appleton, WI 38
US average 41
Unhealthy days / yr better than US avg
Missoula, MT 0
Appleton, WI 1
US average 1

5-Year Air Quality Trend

Air quality is improving in the Missoula, MT metro. Best year: 2024 (237 good days).

Year Good Moderate Unhealthy Median AQI
2020 155 192 6 54
2021 122 213 6 56
2022 149 201 4 54
2023 156 200 0 53
2024 237 125 1 43
2025 151 30 0 38

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Missoula, MT.

Appleton, WI

AQI 38 · 78.5% good

38

Atlantic City-Hammonton, NJ

AQI 38 · 79.6% good

38

Barnstable Town, MA

AQI 38 · 92.5% good

38

Bay City, MI

AQI 38 · 71.8% good

38

Cadillac, MI

AQI 38 · 89.5% good

38

Claremont-Lebanon, NH-VT

AQI 38 · 81.3% good

38

More Air Quality Data

Explore EPA air quality rankings and guides across U.S. metros and counties.

Cleanest Metro Areas

U.S. metros ranked by their share of Good air-quality days.

Worst Air Quality

Counties and metros with the most unhealthy air days.

All Metro Areas

Annual AQI by CBSA for every monitored U.S. metro area.

Best and Worst City Air

What drives urban air quality and how metro areas compare.

Air Quality Guides

Frequently Asked Questions

What is the air quality in the Missoula, MT metro area? ▼
The Missoula, MT metro area has a median Air Quality Index (AQI) of 38, rated "Good." 83.4% of monitored days (151 out of 181) had good air quality in 2025.
How many unhealthy air days does Missoula, MT have? ▼
In 2025, the Missoula, MT metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 82.
Is air quality in Missoula, MT getting better or worse? ▼
Air quality in the Missoula, MT metro is improving based on 5-year trends (2020-2025). Best year: 2024 with 237 good days. Worst year: 2021 with 122 good days.
What does AQI 38 mean for health? ▼
An AQI of 38 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 Missoula, MT? ▼
The 90th percentile AQI for the Missoula, MT metro area is 56, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 82 (Moderate).
How does Missoula, MT compare to other metro areas? ▼
The Missoula, MT metro has 83.4% good air days. Similar metros: Appleton, WI (78.5% good), Atlantic City-Hammonton, NJ (79.6% good), Barnstable Town, MA (92.5% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2025. See our methodology for how AQI, median, and coverage figures are computed.

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

Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary files (metro-level) · 2020–2025

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.