Metro area air quality · 2025

Ann Arbor, MI

Median AQI 41 (Good). 76.0% of monitored days rated Good across this metro's EPA monitoring network.

41
Median AQI
76.0%
Good-air days
1
Unhealthy days
54%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 296 monitored days. EPA AQS →

The verdict

The Ann Arbor, MI metro runs good on the EPA scale, cleaner than the median US metro, a median AQI of 41 with 76.0% of 296 monitored days in the Good band.

41
median AQI · Good
76.0%
days rated Good
54%
cleaner than US metros
152
worst single reading

1 day reached Unhealthy or worse across the metro's monitors in 2025.

Insights: Ann Arbor, MI metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 41 over 296 measured days in 2025, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 225 Good days (76%), 65 Moderate (22%), and 5 Unhealthy-for-Sensitive-Groups (2%). The 90th-percentile AQI finished at 67 while the highest single-day reading hit 152 (Unhealthy). Metro residents averaged roughly 22.8 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -11 and the median AQI moved -2 points, which classifies the multi-year trajectory as improving. The metro recorded 1 unhealthy-or-worse days combined, on those days the EPA recommends that sensitive groups limit prolonged outdoor exertion, and many schools and athletic programs adjust outdoor activity accordingly. Metros with comparable AQI profiles include Adrian, MI (77.3% good, AQI 41); Altoona, PA (71.9% good, AQI 41); Bowling Green, KY (81.2% good, AQI 41).

Air Quality Summary

Median AQI

41

Good

Good Days

76.0%

225 of 296 days

Max AQI

152

Unhealthy

Health Grade

Good

90th pct: 67

AQI Day Breakdown (2025)

Distribution of 296 monitored days across EPA AQI categories.

Good

225

76%

Moderate

65

22%

USG

5

2%

Unhealthy

1

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Ann Arbor, MI metro area's air quality is rated Good based on 76.0% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.

Air quality is acceptable most days, but 5 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 152. Sensitive groups should monitor real-time conditions at AirNow.gov.

How does the Ann Arbor, MI metro compare?

How Ann Arbor, MI compares

Good-day share better than US avg
Ann Arbor, MI 76.0%
Adrian, MI 77.3%
US average 71.3%
Median AQI about average
Ann Arbor, MI 41
Adrian, MI 41
US average 41
Unhealthy days / yr about average
Ann Arbor, MI 1
Adrian, MI 0
US average 1

5-Year Air Quality Trend

Air quality is improving in the Ann Arbor, MI metro. Best year: 2024 (253 good days).

Year Good Moderate Unhealthy Median AQI
2020 236 124 1 43
2021 212 153 0 46
2022 222 142 0 46
2023 168 184 2 52
2024 253 113 0 43
2025 225 65 1 41

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Ann Arbor, MI.

Adrian, MI

AQI 41 · 77.3% good

41

Altoona, PA

AQI 41 · 71.9% good

41

Bowling Green, KY

AQI 41 · 81.2% good

41

Charlottesville, VA

AQI 41 · 77.9% good

41

Clarksville, TN-KY

AQI 41 · 76.8% good

41

Columbia, MO

AQI 41 · 89.1% good

41

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 Ann Arbor, MI metro area? ▼
The Ann Arbor, MI metro area has a median Air Quality Index (AQI) of 41, rated "Good." 76.0% of monitored days (225 out of 296) had good air quality in 2025.
How many unhealthy air days does Ann Arbor, MI have? ▼
In 2025, the Ann Arbor, MI metro area recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 152.
Is air quality in Ann Arbor, MI getting better or worse? ▼
Air quality in the Ann Arbor, MI metro is improving based on 5-year trends (2020-2025). Best year: 2024 with 253 good days. Worst year: 2023 with 168 good days.
What does AQI 41 mean for health? ▼
An AQI of 41 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 Ann Arbor, MI? ▼
The 90th percentile AQI for the Ann Arbor, MI metro area is 67, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 152 (Unhealthy).
How does Ann Arbor, MI compare to other metro areas? ▼
The Ann Arbor, MI metro has 76.0% good air days. Similar metros: Adrian, MI (77.3% good), Altoona, PA (71.9% good), Bowling Green, KY (81.2% 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.