Metro area air quality · 2024

Great Falls, MT

Median AQI 46 (Good). 59.8% of monitored days rated Good across this metro's EPA monitoring network.

46
Median AQI
59.8%
Good-air days
0
Unhealthy days

Great Falls, MT posted a 2024 median AQI of 46 (Good) with 59.8% Good days

According to the U.S. EPA Air Quality System, the Great Falls, MT CBSA recorded a median AQI of 46 across 87 monitored days in 2024, with 59.8% rated Good and 0 unhealthy or worse. This is an annual metro comparison, not a live advisory.

Data source EPA Air Quality System (AQS)

Closest median-AQI peer
Ada, OK (71.6% Good, median AQI 43) is the closest nationwide median-AQI peer to Great Falls, MT.
2020–2024 Good-day shift
Great Falls, MT's Good-day share moved -28.4 points from 2020 to 2024 (median AQI +22).
Median AQI
Median AQI: 46
Good days
Good days: 59.8%

Aggregated from EPA Air Quality System (2024), 87 monitored days. EPA AQS →

The verdict

Great Falls, MT lands in the lower Good-day tercile (59.8% Good), a thinner clean-air share than most CBSA peers here. On the EPA scale the metro runs good, with a median AQI of 46 and 59.8% of 87 monitored days in the Good band.

46
median AQI · Good
59.8%
days rated Good
74
worst single reading

No day crossed into the Unhealthy tier across the metro's monitors in 2024.

Annual release change

What changed in the 2023 EPA annual release

2022 → 2023
  • Great Falls, MT metro's Good-day share fell from 90.5% to 50.9% between the 2022 and 2023 EPA annual releases, a change of -39.6 percentage points.
  • Great Falls, MT metro's median AQI rose from 23 to 50 between the 2022 and 2023 EPA annual releases, a change of +27 points.
  • Great Falls, MT metro's peak single-day AQI rose from 128 to 170 between the 2022 and 2023 EPA annual releases, a change of +42 points.
  • Great Falls, MT metro's Unhealthy-category days rose from 0 to 1 between the 2022 and 2023 EPA annual releases, a change of +1 days.

Compared against 357 monitored days in 2022 and 346 in 2023. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Great Falls, MT lands in the lower Good-day tercile (59.8% Good), a thinner clean-air share than most CBSA peers here. Signature read: 59.8% Good-day share (low tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 46 over 87 measured days in 2024 (Good / Moderate). The monitored-day split lands at 52 Good (60%), 35 Moderate (40%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 58; the highest single-day reading hit 74 (Moderate).

Across 2020–2024, Good-day share shifted -28.4 points and median AQI moved +22 (worsening). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Ada, OK (71.6% good, AQI 43); Summerville, GA (96.3% good, AQI 39); Americus, GA (93.4% good, AQI 38).

Health effects of air pollution →

Air Quality Summary

Median AQI

46

Good

Good Days

59.8%

52 of 87 days

Max AQI

74

Moderate

Health Grade

Moderate

90th pct: 58

AQI Day Breakdown (2024)

Distribution of 87 monitored days across EPA AQI categories.

Good

52

60%

Moderate

35

40%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Great Falls, MT metro area's air quality is rated Moderate based on 59.8% good air days. No unhealthy air days were recorded in 2024.

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

How does the Great Falls, MT metro compare?

How Great Falls, MT compares

Good-day share worse than typical
Great Falls, MT 59.8%
Ada, OK 71.6%
Typical US metro 70.6%
Median AQI worse than typical
Great Falls, MT 46
Ada, OK 43
Typical US metro 41
Unhealthy days / yr better than typical
Great Falls, MT 0
Ada, OK 0
Typical US metro 1

5-Year Air Quality Trend

Air quality is worsening in the Great Falls, MT metro. Highest Good-day share: 2022 (90.5%, 323 of 357 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 314 42 0 24
2021 296 58 2 27
2022 323 34 0 23
2023 176 169 1 50
2024 52 35 0 46

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Great Falls, MT (46).

Ada, OK

Median AQI 43 · 71.6% Good-day share

43

Summerville, GA

Median AQI 39 · 96.3% Good-day share

39

Americus, GA

Median AQI 38 · 93.4% Good-day share

38

Frequently Asked Questions

How many unhealthy air days does Great Falls, MT have? ▼
In 2024, the Great Falls, MT metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 74.
What is the air quality in the Great Falls, MT metro area? ▼
The Great Falls, MT metro area has a median Air Quality Index (AQI) of 46, rated "Good." 59.8% of monitored days (52 out of 87) had good air quality in 2024.
Is air quality in Great Falls, MT getting better or worse? ▼
Air quality in the Great Falls, MT metro is worsening across floor-qualifying years (2020-2023); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2022 at 90.5% (323 of 357 days). Lowest qualifying Good-day share: 2023 at 50.9% (176 of 346 days).
What does AQI 46 mean for health? ▼
An AQI of 46 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 Great Falls, MT compare to other metro areas? ▼
The Great Falls, MT metro has 59.8% good air days. Similar metros: Ada, OK (71.6% good), Summerville, GA (96.3% good), Americus, GA (93.4% good).
What is the 90th percentile AQI for Great Falls, MT? ▼
The 90th percentile AQI for the Great Falls, MT metro area is 58, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 74 (Moderate).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Great Falls, MT, 2024. 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, Great Falls, MT · 2020–2025