Marshall, Minnesota Air Quality
Marshall has a median AQI of 37, earning an air quality grade of A — excellent air quality that ranks better than 74% of US cities. Air quality has been trending worse over the past decade, a concern for local residents and health officials. Ground-level ozone is the primary concern, typically peaking on warm sunny days due to vehicle and industrial emissions. In 2025, Marshall recorded 153 good air quality days (85% of monitored days) and 1 unhealthy days.
Population: 13,896 • County: Lyon
Current AQI
Quick Facts
| Current AQI | 17 — Good |
| Air Quality Grade | A |
| Median AQI (2025) | 37 |
| vs. U.S. Cities | Better than 74% |
| Primary Pollutant | Ozone |
| Unhealthy Days/Year | 1 |
| 10-Year Trend | ↓ Worsening |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is satisfactory, and air pollution poses little or no risk.
It's a great day to be active outside!
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for Marshall is sourced from the Marshall monitoring area, located approximately 2 miles from city center. This EPA-certified station continuously tracks ground-level ozone, the primary driver of air quality alerts in this area.
Marshall has relatively consistent air quality throughout the year without a strong seasonal peak. Air quality is primarily influenced by local traffic, industrial activity, and regional weather patterns rather than a single seasonal driver.
AQI Trend (10 Years)
Air Quality Days by Year
Marshall Median AQI by Year
Annual EPA air quality data for Marshall — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 37 | 153 | 1 | 140 | Ozone |
| 2024 | 40 | 276 | 2 | 142 | PM2.5 |
| 2023 | 46 | 206 | 13 | 173 | PM2.5 |
| 2022 | 38 | 303 | 2 | 172 | Ozone |
| 2021 | 39 | 263 | 5 | 187 | PM2.5 |
| 2020 | 35 | 309 | — | 80 | PM2.5 |
| 2019 | 34 | 306 | — | 87 | PM2.5 |
| 2018 | 36 | 308 | — | 86 | PM2.5 |
| 2017 | 35 | 307 | — | 96 | Ozone |
| 2016 | 32 | 327 | 1 | 110 | Ozone |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2025 Air Quality Summary
Primary Pollutant Days (2025)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About Marshall Air Quality
What is the air quality in Marshall today?
The current AQI in Marshall is 17, rated "Good". Air quality is good — outdoor activity is safe for everyone today. Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in Marshall getting better or worse?
Air quality in Marshall has been worsening. The median AQI has risen 5 points (from 32 in 2016 to 37 in 2025), a concern for local health officials.
What is the most common air pollutant in Marshall?
Ozone is the primary air pollutant in Marshall, responsible for 117 days (65% of monitored days) in 2025. Ground-level ozone forms when sunlight reacts with emissions from vehicles and industry, typically peaking on hot summer afternoons.
How many unhealthy air days does Marshall have per year?
In 2025, Marshall recorded 85% good air quality days (153 days) out of 181 monitored days. There were 1 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 140.
What air quality grade does Marshall receive?
Marshall receives an air quality grade of A, placing it better than 74% of US cities. This is based on a median AQI of 37 in 2025, with 153 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 74% of US cities
Nearby Cities
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National Rankings
See how Marshall compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Marshall
Ozone is Marshall's primary pollutant. Standard HEPA filters don't capture ozone molecules — you need activated carbon or PECO technology to chemically break them down. We highlight those units here.
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Molekule Air Pro
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