Metro area air quality · 2025

Duluth, MN-WI

Median AQI 42 (Good). 66.3% of monitored days rated Good across this metro's EPA monitoring network.

42
Median AQI
66.3%
Good-air days
12
Unhealthy days
37%
Cleaner than US metros

Duluth, MN-WI posted a 2025 median AQI of 42 (Good) with 66.3% Good days

According to the U.S. EPA Air Quality System, the Duluth, MN-WI CBSA recorded a median AQI of 42 across 365 monitored days in 2025, with 66.3% rated Good and 12 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 Duluth, MN-WI CBSA's 66.3% Good-day share places it cleaner than 37% of US metros in 2025.
Closest median-AQI peer
Allentown-Bethlehem-Easton, PA-NJ (66.8% Good, median AQI 42) is the closest nationwide median-AQI peer to Duluth, MN-WI.
2020–2025 Good-day shift
Duluth, MN-WI's Good-day share moved -7.9 points from 2020 to 2025 (median AQI +1).
Median AQI
Median AQI: 42

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

The verdict

Duluth, MN-WI's peak reading 216 is in the upper max-AQI tercile among CBSA metros here. On the EPA scale the metro runs good, more polluted than the median US metro, with a median AQI of 42 and 66.3% of 365 monitored days in the Good band.

42
median AQI · Good
66.3%
days rated Good
37%
cleaner than US metros
216
worst single reading

12 days reached Unhealthy or worse across the metro's monitors in 2025.

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • Duluth, MN-WI metro's Unhealthy-category days rose from 0 to 11 between the 2024 and 2025 EPA annual releases, a change of +11 days.
  • Duluth, MN-WI metro's Good-day share fell from 78.8% to 68.6% between the 2024 and 2025 EPA annual releases, a change of -10.2 percentage points.
  • Duluth, MN-WI metro's peak single-day AQI rose from 114 to 216 between the 2024 and 2025 EPA annual releases, a change of +102 points.
  • Duluth, MN-WI metro's median AQI rose from 39 to 42 between the 2024 and 2025 EPA annual releases, a change of +3 points.

Compared against 363 monitored days in 2024 and 353 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

Duluth, MN-WI's peak reading 216 is in the upper max-AQI tercile among CBSA metros here. Signature read: peak AQI 216 (high tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 42 over 365 measured days in 2025 (Good / Moderate). The monitored-day split lands at 242 Good (66%), 100 Moderate (27%), and 11 Unhealthy-for-Sensitive-Groups (3%). The 90th-percentile AQI finished at 79; the highest single-day reading hit 216 (Very Unhealthy).

Across 2020–2025, Good-day share shifted -7.9 points and median AQI moved +1 (worsening). The annual record contains 12 days at Unhealthy or worse. Metros with comparable AQI profiles include Allentown-Bethlehem-Easton, PA-NJ (66.8% good, AQI 42); Amarillo, TX (78.4% good, AQI 42); Carson City, NV (86.2% good, AQI 42).

Health effects of air pollution →

Air Quality Summary

Median AQI

42

Good

Good Days

66.3%

242 of 365 days

Max AQI

216

Very Unhealthy

Health Grade

Moderate

90th pct: 79

AQI Day Breakdown (2025)

Distribution of 365 monitored days across EPA AQI categories.

Good

242

66%

Moderate

100

27%

USG

11

3%

Unhealthy

11

3%

Very Unhealthy

1

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Duluth, MN-WI metro area's air quality is rated Moderate based on 66.3% good air days. There were 12 unhealthy days in 2025 when outdoor activity should be limited.

Air quality reached unhealthy levels on 12 days in 2025 (11 Unhealthy, 1 Very Unhealthy). Sensitive groups, including people with asthma, COPD, cardiovascular conditions, children, and adults over 65, should review the daily breakdown and follow local advisories.

Sensitive group advisory

People with asthma, COPD, heart disease, children, pregnant women, and adults 65+ should follow EPA AQI alerts daily and limit outdoor exertion when AQI exceeds 100. Real-time conditions: airnow.gov.

How does the Duluth, MN-WI metro compare?

How Duluth, MN-WI compares

Good-day share worse than typical
Duluth, MN-WI 66.3%
Allentown-Bethlehem-Easton, PA-NJ 66.8%
Typical US metro 70.6%
Median AQI worse than typical
Duluth, MN-WI 42
Allentown-Bethlehem-Easton, PA-NJ 42
Typical US metro 41
Unhealthy days / yr worse than typical
Duluth, MN-WI 12
Allentown-Bethlehem-Easton, PA-NJ 0
Typical US metro 1

5-Year Air Quality Trend

Air quality is worsening in the Duluth, MN-WI metro. Highest Good-day share: 2022 (88.2%, 322 of 365 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 279 86 0 41
2021 278 76 2 38
2022 322 43 0 36
2023 219 138 1 44
2024 286 77 0 39
2025 242 100 11 42

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Duluth, MN-WI (42).

Allentown-Bethlehem-Easton, PA-NJ

Median AQI 42 · 66.8% Good-day share

42

Amarillo, TX

Median AQI 42 · 78.4% Good-day share

42

Carson City, NV

Median AQI 42 · 86.2% Good-day share

42

Casper, WY

Median AQI 42 · 86.3% Good-day share

42

Clarksville, TN-KY

Median AQI 42 · 72.0% Good-day share

42

Daphne-Fairhope-Foley, AL

Median AQI 42 · 75.5% Good-day share

42

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Duluth, MN-WI's 12 (independent of median AQI).

Houston-The Woodlands-Sugar Land, TX

11 unhealthy-or-worse days · median AQI 63

63

Phoenix-Mesa-Scottsdale, AZ

13 unhealthy-or-worse days · median AQI 78

78

El Centro, CA

10 unhealthy-or-worse days · median AQI 64

64

Fairbanks, AK

10 unhealthy-or-worse days · median AQI 44

44

Bemidji, MN

9 unhealthy-or-worse days · median AQI 36

36

Deming, NM

9 unhealthy-or-worse days · median AQI 17

17

Frequently Asked Questions

What is the 90th percentile AQI for Duluth, MN-WI? ▼
The 90th percentile AQI for the Duluth, MN-WI metro area is 79, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 216 (Very Unhealthy).
How many unhealthy air days does Duluth, MN-WI have? ▼
In 2025, the Duluth, MN-WI metro area recorded 12 unhealthy air days (11 Unhealthy, 1 Very Unhealthy, 0 Hazardous). The maximum AQI reached 216.
What is the air quality in the Duluth, MN-WI metro area? ▼
The Duluth, MN-WI metro area has a median Air Quality Index (AQI) of 42, rated "Good." 66.3% of monitored days (242 out of 365) had good air quality in 2025.
Is air quality in Duluth, MN-WI getting better or worse? ▼
Air quality in the Duluth, MN-WI 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: 2022 at 88.2% (322 of 365 days). Lowest qualifying Good-day share: 2023 at 61.2% (219 of 358 days).
What does AQI 42 mean for health? ▼
An AQI of 42 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 Duluth, MN-WI compare to other metro areas? ▼
The Duluth, MN-WI metro has 66.3% good air days. Similar metros: Allentown-Bethlehem-Easton, PA-NJ (66.8% good), Amarillo, TX (78.4% good), Carson City, NV (86.2% good).

Data Sources

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