Metro area air quality · 2025
Marquette, MI
Median AQI 18 (Good). 87.0% of monitored days rated Good across this metro's EPA monitoring network.
- 18
- Median AQI
- 87.0%
- Good-air days
- 1
- Unhealthy days
- 79%
- Cleaner than US metros
Aggregated from EPA Air Quality System (2025), 123 monitored days. EPA AQS →
The verdict
The Marquette, MI metro runs good on the EPA scale, cleaner than most US metros, a median AQI of 18 with 87.0% of 123 monitored days in the Good band.
- 18
- median AQI · Good
- 87.0%
- days rated Good
- 79%
- cleaner than US metros
- 183
- worst single reading
1 day reached Unhealthy or worse across the metro's monitors in 2025.
Insights: Marquette, MI metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 18 over 123 measured days in 2025, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 107 Good days (87%), 15 Moderate (12%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 56 while the highest single-day reading hit 183 (Unhealthy). Metro residents averaged roughly 26.1 clean-air days per 30-day window across the reporting year.
Across the 2024–2025 trend window, good days shifted by -95 and the median AQI moved -1 points, which classifies the multi-year trajectory as worsening. 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 Centralia, WA (93.3% good, AQI 18); Guayama, PR (100.0% good, AQI 18); Aberdeen, WA (97.9% good, AQI 19).
Air Quality Summary
Median AQI
18
Good
Good Days
87.0%
107 of 123 days
Max AQI
183
Unhealthy
Health Grade
Good
90th pct: 56
AQI Day Breakdown (2025)
Distribution of 123 monitored days across EPA AQI categories.
Good
107
87%
Moderate
15
12%
USG
0
0%
Unhealthy
1
1%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The Marquette, MI metro area's air quality is rated Good based on 87.0% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 0 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 183. Sensitive groups should monitor real-time conditions at AirNow.gov.
How does the Marquette, MI metro compare?
How Marquette, MI compares
5-Year Air Quality Trend
Air quality is worsening in the Marquette, MI metro. Best year: 2024 (202 good days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2024 | 202 | 22 | 0 | 19 | 67 |
| 2025 | 107 | 15 | 1 | 18 | 183 |
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Air Quality Guides
Frequently Asked Questions
What is the air quality in the Marquette, MI metro area? ▼
How many unhealthy air days does Marquette, MI have? ▼
Is air quality in Marquette, MI getting better or worse? ▼
What does AQI 18 mean for health? ▼
What is the 90th percentile AQI for Marquette, MI? ▼
How does Marquette, MI compare to other metro areas? ▼
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.