Metro area air quality · 2025

Helena, MT

Median AQI 44 (Good). 71.5% of monitored days rated Good across this metro's EPA monitoring network.

Compiled by PlainAirData · August 23, 2026

44
Median AQI: 71.5%
Good-air days: 0
Unhealthy days: 48%
Cleaner than US metros

Helena, MT posted a 2025 median AQI of 44 (Good) with 71.5% Good days

According to the U.S. EPA Air Quality System, the Helena, MT CBSA recorded a median AQI of 44 across 365 monitored days in 2025, with 71.5% rated Good and 0 unhealthy or worse. This is an annual metro comparison, not a live advisory.

Data source EPA Air Quality System (AQS)

Cleaner than US metros: The Helena, MT CBSA's 71.5% Good-day share places it cleaner than 48% of US metros in 2025.
Closest median-AQI peer: Bartlesville, OK (68.0% Good, median AQI 44) is the closest nationwide median-AQI peer to Helena, MT.
2020–2025 Good-day shift: Helena, MT's Good-day share moved -4.4 points from 2020 to 2025 (median AQI +2).
Median AQI: Median AQI: 44

Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →

The verdict

Helena, MT's peak reading 93 stays in the lower max-AQI tercile on this extract. On the EPA scale the metro runs good, more polluted than the median US metro, with a median AQI of 44 and 71.5% of 365 monitored days in the Good band.

44
median AQI · Good: 71.5%
days rated Good: 48%
cleaner than US metros: 93
worst single reading

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

Helena, MT metro's Good-day share rose from 64.5% to 71.5% between the 2024 and 2025 EPA annual releases, a change of +7.0 percentage points.
Helena, MT metro's peak single-day AQI fell from 160 to 93 between the 2024 and 2025 EPA annual releases, a change of -67 points.
Helena, MT metro's Unhealthy-category days fell from 1 to 0 between the 2024 and 2025 EPA annual releases, a change of -1 days.

Helena, MT's peak reading 93 stays in the lower max-AQI tercile on this extract. Signature read: peak AQI 93 (low tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 44 over 365 measured days in 2025 (Good / Moderate). The monitored-day split lands at 261 Good (72%), 104 Moderate (28%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 65; the highest single-day reading hit 93 (Moderate).

Across 2020–2025, Good-day share shifted -4.4 points and median AQI moved +2 (worsening). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Bartlesville, OK (68.0% good, AQI 44); Berlin, NH-VT (81.5% good, AQI 44); Bloomington, IL (66.0% good, AQI 44).

Understanding AQI →

Air Quality Summary

Median AQI

Good

Good Days

71.5%

261 of 365 days

Max AQI

Moderate

Health Grade

Moderate

90th pct: 65

AQI Day Breakdown (2025)

Distribution of 365 monitored days across EPA AQI categories.

Good

261

72%

Moderate

104

28%

USG

Unhealthy

Very Unhealthy

Hazardous

Health Impact Assessment

Moderate

The Helena, MT metro area's air quality is rated Moderate based on 71.5% 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

Compare against

Good-day share better than typical

Helena, MT 71.5%

Bartlesville, OK 68.0%

Typical US metro 70.6%

Median AQI worse than typical

Helena, MT 44

Bartlesville, OK 44

Typical US metro 41

Unhealthy days / yr better than typical

Helena, MT 0

Bartlesville, OK 1

Typical US metro 1

5-Year Air Quality Trend

Air quality is worsening in the Helena, MT metro. Highest Good-day share: 2020 (75.9%, 277 of 365 monitored days).

Year	Good	Moderate	Unhealthy	Median AQI	Max AQI
2020	277	84	4	42	168
2021	249	99	3	44	156
2022	239	119	3	45	167
2023	240	120	2	45	165
2024	233	127	1	46	160
2025	261	104	0	44	93

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Helena, MT (44).

Bartlesville, OK

Median AQI 44 · 68.0% Good-day share

Berlin, NH-VT

Median AQI 44 · 81.5% Good-day share

Bloomington, IL

Median AQI 44 · 66.0% Good-day share

Boston-Cambridge-Newton, MA-NH

Median AQI 44 · 71.0% Good-day share

Bridgeport-Stamford-Norwalk, CT

Median AQI 44 · 64.7% Good-day share

Buffalo-Cheektowaga-Niagara Falls, NY

Median AQI 44 · 63.8% Good-day share

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Helena, MT's 0 (independent of median AQI).

Aberdeen, SD

0 unhealthy-or-worse days · median AQI 27

Aberdeen, WA

0 unhealthy-or-worse days · median AQI 22

Adrian, MI

0 unhealthy-or-worse days · median AQI 41

Akron, OH

0 unhealthy-or-worse days · median AQI 45

Albany, GA

0 unhealthy-or-worse days · median AQI 46

Albany, OR

0 unhealthy-or-worse days · median AQI 27

Frequently Asked Questions

What is the 90th percentile AQI for Helena, MT? ▼

The 90th percentile AQI for the Helena, MT metro area is 65, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 93 (Moderate).

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.

What is the air quality in the Helena, MT metro area? ▼

The Helena, MT metro area has a median Air Quality Index (AQI) of 44, rated "Good." 71.5% of monitored days (261 out of 365) had good air quality in 2025.

Is air quality in Helena, MT getting better or worse? ▼

Air quality in the Helena, MT metro is worsening across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2020 at 75.9% (277 of 365 days). Lowest qualifying Good-day share: 2024 at 64.5% (233 of 361 days).

What does AQI 44 mean for health? ▼

An AQI of 44 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.

How does Helena, MT compare to other metro areas? ▼

The Helena, MT metro has 71.5% good air days. Similar metros: Bartlesville, OK (68.0% good), Berlin, NH-VT (81.5% good), Bloomington, IL (66.0% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Helena, MT, 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, Helena, MT · 2020–2025 Accessed 2026-07-06