Metro area air quality · 2025

Helena, MT

Median AQI 45 (Good). 65.4% of monitored days rated Good across this metro's EPA monitoring network.

45
Median AQI
65.4%
Good-air days
0
Unhealthy days
34%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 182 monitored days. EPA AQS →

The verdict

The Helena, MT metro runs good on the EPA scale, more polluted than the median US metro, a median AQI of 45 with 65.4% of 182 monitored days in the Good band.

45
median AQI · Good
65.4%
days rated Good
34%
cleaner than US metros
93
worst single reading

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

Insights: Helena, MT metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 45 over 182 measured days in 2025, which corresponds to a Good band and a Moderate metro-wide health grade. The monitored-day split lands at 119 Good days (65%), 63 Moderate (35%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 69 while the highest single-day reading hit 93 (Moderate). Metro residents averaged roughly 19.6 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -158 and the median AQI moved +3 points, which classifies the multi-year trajectory as worsening. 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 Akron, OH (62.2% good, AQI 45); Carson City, NV (79.3% good, AQI 45); Clinton, IA (59.9% good, AQI 45).

Air Quality Summary

Median AQI

45

Good

Good Days

65.4%

119 of 182 days

Max AQI

93

Moderate

Health Grade

Moderate

90th pct: 69

AQI Day Breakdown (2025)

Distribution of 182 monitored days across EPA AQI categories.

Good

119

65%

Moderate

63

35%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Helena, MT metro area's air quality is rated Moderate based on 65.4% 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 Helena, MT metro compare?

How Helena, MT compares

Good-day share worse than US avg
Helena, MT 65.4%
Akron, OH 62.2%
US average 71.3%
Median AQI worse than US avg
Helena, MT 45
Akron, OH 45
US average 41
Unhealthy days / yr better than US avg
Helena, MT 0
Akron, OH 0
US average 1

5-Year Air Quality Trend

Air quality is worsening in the Helena, MT metro. Best year: 2020 (277 good days).

Year Good Moderate Unhealthy Median AQI
2020 277 84 4 42
2021 249 99 3 44
2022 239 119 3 45
2023 240 120 2 45
2024 233 127 1 46
2025 119 63 0 45

Metros with Similar Air Quality

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

Akron, OH

AQI 45 · 62.2% good

45

Carson City, NV

AQI 45 · 79.3% good

45

Clinton, IA

AQI 45 · 59.9% good

45

Davenport-Moline-Rock Island, IA-IL

AQI 45 · 58.4% good

45

Española, NM

AQI 45 · 79.9% good

45

Gadsden, AL

AQI 45 · 63.5% good

45

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 Helena, MT metro area? ▼
The Helena, MT metro area has a median Air Quality Index (AQI) of 45, rated "Good." 65.4% of monitored days (119 out of 182) had good air quality in 2025.
How many unhealthy air days does Helena, MT have? ▼
In 2025, the Helena, MT metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 93.
Is air quality in Helena, MT getting better or worse? ▼
Air quality in the Helena, MT metro is worsening based on 5-year trends (2020-2025). Best year: 2020 with 277 good days. Worst year: 2025 with 119 good days.
What does AQI 45 mean for health? ▼
An AQI of 45 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 Helena, MT? ▼
The 90th percentile AQI for the Helena, MT metro area is 69, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 93 (Moderate).
How does Helena, MT compare to other metro areas? ▼
The Helena, MT metro has 65.4% good air days. Similar metros: Akron, OH (62.2% good), Carson City, NV (79.3% good), Clinton, IA (59.9% 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.