Metro area air quality · 2025

Billings, MT

Median AQI 38 (Good). 86.3% of monitored days rated Good across this metro's EPA monitoring network.

38
Median AQI
86.3%
Good-air days
0
Unhealthy days
81%
Cleaner than US metros

Billings, MT posted a 2025 median AQI of 38 (Good) with 86.3% Good days

According to the U.S. EPA Air Quality System, the Billings, MT CBSA recorded a median AQI of 38 across 365 monitored days in 2025, with 86.3% 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 Billings, MT CBSA's 86.3% Good-day share places it cleaner than 81% of US metros in 2025.
Closest median-AQI peer
Appleton, WI (72.3% Good, median AQI 38) is the closest nationwide median-AQI peer to Billings, MT.
2020–2025 Good-day shift
Billings, MT's Good-day share moved +2.3 points from 2020 to 2025 (median AQI +7).
Median AQI
Median AQI: 38

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

The verdict

Billings, MT sits in the upper Good-day tercile among EPA CBSA metros on this site (86.3% of 365 monitored days). On the EPA scale the metro runs good, cleaner than most US metros, with a median AQI of 38 and 86.3% of 365 monitored days in the Good band.

38
median AQI · Good
86.3%
days rated Good
81%
cleaner than US metros
91
worst single reading

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

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • Billings, MT metro's Good-day share rose from 76.4% to 86.3% between the 2024 and 2025 EPA annual releases, a change of +9.9 percentage points.
  • Billings, MT metro's peak single-day AQI fell from 105 to 91 between the 2024 and 2025 EPA annual releases, a change of -14 points.

Compared against 356 monitored days in 2024 and 365 in 2025. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Billings, MT sits in the upper Good-day tercile among EPA CBSA metros on this site (86.3% of 365 monitored days). Signature read: 86.3% Good-day share (high tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 38 over 365 measured days in 2025 (Good / Good). The monitored-day split lands at 315 Good (86%), 50 Moderate (14%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 54; the highest single-day reading hit 91 (Moderate).

Across 2020–2025, Good-day share shifted +2.3 points and median AQI moved +7 (worsening). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Appleton, WI (72.3% good, AQI 38); Burlington-South Burlington, VT (87.7% good, AQI 38); Charlottesville, VA (81.0% good, AQI 38).

Best and worst city air quality →

Air Quality Summary

Median AQI

38

Good

Good Days

86.3%

315 of 365 days

Max AQI

91

Moderate

Health Grade

Good

90th pct: 54

AQI Day Breakdown (2025)

Distribution of 365 monitored days across EPA AQI categories.

Good

315

86%

Moderate

50

14%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Billings, MT metro area's air quality is rated Good based on 86.3% 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 Billings, MT metro compare?

How Billings, MT compares

Good-day share better than typical
Billings, MT 86.3%
Appleton, WI 72.3%
Typical US metro 70.6%
Median AQI better than typical
Billings, MT 38
Appleton, WI 38
Typical US metro 41
Unhealthy days / yr better than typical
Billings, MT 0
Appleton, WI 6
Typical US metro 1

5-Year Air Quality Trend

Air quality is worsening in the Billings, MT metro. Highest Good-day share: 2023 (86.4%, 306 of 354 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 304 57 1 31
2021 212 118 1 40
2022 307 56 1 32
2023 306 47 1 29
2024 272 84 0 39
2025 315 50 0 38

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Billings, MT (38).

Appleton, WI

Median AQI 38 · 72.3% Good-day share

38

Burlington-South Burlington, VT

Median AQI 38 · 87.7% Good-day share

38

Charlottesville, VA

Median AQI 38 · 81.0% Good-day share

38

Corning, NY

Median AQI 38 · 83.3% Good-day share

38

Dickinson, ND

Median AQI 38 · 82.7% Good-day share

38

Eau Claire, WI

Median AQI 38 · 73.7% Good-day share

38

Metros with similar unhealthy-day exposure

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

Aberdeen, SD

0 unhealthy-or-worse days · median AQI 27

27

Aberdeen, WA

0 unhealthy-or-worse days · median AQI 22

22

Adrian, MI

0 unhealthy-or-worse days · median AQI 41

41

Akron, OH

0 unhealthy-or-worse days · median AQI 45

45

Albany, GA

0 unhealthy-or-worse days · median AQI 46

46

Albany, OR

0 unhealthy-or-worse days · median AQI 27

27

Frequently Asked Questions

How many unhealthy air days does Billings, MT have? ▼
In 2025, the Billings, MT metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 91.
What is the air quality in the Billings, MT metro area? ▼
The Billings, MT metro area has a median Air Quality Index (AQI) of 38, rated "Good." 86.3% of monitored days (315 out of 365) had good air quality in 2025.
Is air quality in Billings, MT getting better or worse? ▼
Air quality in the Billings, 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: 2023 at 86.4% (306 of 354 days). Lowest qualifying Good-day share: 2021 at 64.0% (212 of 331 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.
How does Billings, MT compare to other metro areas? ▼
The Billings, MT metro has 86.3% good air days. Similar metros: Appleton, WI (72.3% good), Burlington-South Burlington, VT (87.7% good), Charlottesville, VA (81.0% good).
What is the 90th percentile AQI for Billings, MT? ▼
The 90th percentile AQI for the Billings, MT metro area is 54, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 91 (Moderate).

Data Sources

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