State air quality · 2025

Minnesota Air Quality Ranking

Across 23 monitored counties, the typical county in Minnesota posts a median AQI of 35 (Good) and 76.8% of monitored days were rated Good, from EPA AQS.

35
Avg median AQI
76.8%
Good-air days
23
Counties monitored
52%
Cleaner than US states

Minnesota's typical county median AQI is 35 (Good) across 23 monitored counties

According to the U.S. EPA Air Quality System, Minnesota monitors 23 counties with a day-weighted Good-day share of 76.8%. Cleanest: Mille Lacs County (95.3% Good). Most polluted: Hennepin County (57.8%). These are annual summaries, not live AirNow readings.

Data source EPA Air Quality System (AQS)

Cleaner than US states
Minnesota's day-weighted Good-day share of 76.8% places it cleaner than 52% of US states.
In-state spread
Within Minnesota, Mille Lacs County leads at 95.3% Good days while Hennepin County sits at 57.8% across 23 monitored counties.
2024→2025 release
Minnesota's Good-day share moved -3.0 points vs the 2024 EPA annual release.
Typical median AQI
Typical median AQI: 35

Verify with AirNow → · EPA AQS →

EPA state monitoring brief

AQS state key MINNESOTA

Minnesota · 2025 EPA AQS · 23 counties · med AQI 35 · 76.8% Good · Mille Lacs→Hennepin spread

  • GOOD 35 Median AQI · Good
  • SHARE 76.8% Good-day share
  • COUNT 23 Counties monitored
  • UNH 102 Unhealthy+ days
  • RANK 52% Cleaner than states
  • PM25 61.3% Main pollutant share

Good-day share peers

Oregon76.9%Minnesota (this)76.8%Connecticut76.7%Nevada76.5%
Good-day share neighbourhood · nearest ABS peers vs Minnesota

Minnesota's 76.8% Good-day share is cleaner than 52% of monitored US states; Mille Lacs and Hennepin County bracket the in-state range. Open Mille Lacs County →

According to EPA AQS annual summaries on PlainAirData, Minnesota ranks #25 of 52 by day-weighted good-day share (76.8%) and #12 by mean county median AQI (34.6). Hawaii is #1 of 52 by day-weighted good-day share (93.8% of monitored days) at mean county median-AQI #4 (27.3) ≠ Alaska #1 lowest mean county median AQI (20.3) at good-day share #8 (84.4%).

Data updated August 2026

What changed, what drives it, and how thick is the sample

Three derived views WPR-style word count does not substitute for: release-over-release movement from county annual rows, the EPA main-pollutant day mix, and how many counties sit below the 100-day ranking floor.

Release change

76.8%

Good-day share in 2025, down 3.0 percentage points vs 2024. County-mean median AQI 35, 1.6 points lower (cleaner) than 2024.

Pollutant mix

PM2.5

Main driver on 61.3% of pollutant-assigned days.

  • PM2.5 61.3%
  • Ozone 37.2%
  • PM10 0.9%
  • NO2 0.5%

Monitoring coverage

318

Average monitored days per county in the latest release. 2 of 23 counties sit below the 100-day floor used for cleanest/most-polluted claims.

Counties Monitored

23

Good Days %

76.8%

Avg Median AQI

35

Total Unhealthy Days

102

Best Air Quality

Mille Lacs County

Worst Air Quality

Hennepin County

Where Minnesota sits nationally

COUNT-derived placement among 52 US states with at least 365 monitored days in the latest county release. Minnesota's day-weighted Good-day share is 76.8% - cleaner than 52% of that comparison set.

Minnesota Good-day share vs. every US state

Day-weighted share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release

76.8% Cleaner than 52% higher than 52% of 52 US states

0.0%–5.0%: 0 US states (0%). Below this entry. 5.0%–10.0%: 0 US states (0%). Below this entry. 10.0%–15.0%: 0 US states (0%). Below this entry. 15.0%–20.0%: 0 US states (0%). Below this entry. 20.0%–25.0%: 0 US states (0%). Below this entry. 25.0%–30.0%: 0 US states (0%). Below this entry. 30.0%–35.0%: 0 US states (0%). Below this entry. 35.0%–40.0%: 0 US states (0%). Below this entry. 40.0%–45.0%: 0 US states (0%). Below this entry. 45.0%–50.0%: 0 US states (0%). Below this entry. 50.0%–55.0%: 0 US states (0%). Below this entry. 55.0%–60.0%: 0 US states (0%). Below this entry. 60.0%–65.0%: 2 US states (4%). Below this entry. 65.0%–70.0%: 9 US states (17%). Below this entry. 70.0%–75.0%: 11 US states (21%). Below this entry. 75.0%–80.0%: 11 US states (21%). This entry sits in this band. 80.0%–85.0%: 13 US states (25%). Above this entry. 85.0%–90.0%: 5 US states (10%). Above this entry. 90.0%–95.0%: 1 US states (2%). Above this entry. 95.0%–100.0%: 0 US states (0%). Above this entry. 100.0%–105.0%: 0 US states (0%). Above this entry. This state 0.0% 100% every floor-qualified US state, bucketed by value

Each bar is a band; taller bars hold more US states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.

Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2025

Which counties in Minnesota have the cleanest and most polluted air?

Cleanest counties in Minnesota

Share of monitored days rated Good (AQI 0–50)

  1. 1 Mille Lacs County 95.3%
  2. 2 Washington County 94.9%
  3. 3 Pine County 94.2%
  4. 4 Goodhue County 89.5%
  5. 5 Cook County 88%
  6. 6 Lake County 85.9%
  7. 7 Winona County 83.8%
  8. 8 Carlton County 82.8%
  9. 9 Cass County 82.7%
  10. 10 Beltrami County 79.1%
  11. 11 Crow Wing County 77.8%
  12. 12 Lyon County 77%

Good-day share · EPA Air Quality System

County Good % Median AQI
Mille Lacs 95.3% 34
Washington 94.9% 34
Pine 94.2% 23
Goodhue 89.5% 38
Cook 88.0% 16
Lake 85.9% 31
Winona 83.8% 21
Carlton 82.8% 33
Cass 82.7% 28
Beltrami 79.1% 36
Crow Wing 77.8% 37
Lyon 77.0% 37
Stearns 75.6% 37
Anoka 74.1% 38
Becker 74.0% 38
Dakota 73.2% 35
Wright 73.1% 39
Scott 72.9% 38
Ramsey 70.1% 34
Olmsted 69.5% 39
Saint Louis 66.6% 42
Blue Earth 65.3% 42
Hennepin 57.8% 45

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025. See our methodology for how AQI and median figures are computed.

Coverage: 23 counties in Minnesota with active monitoring stations. Unmonitored counties are not represented.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files, aggregated to the state level · 2020–2025

Every figure on PlainAirData 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.

Informational only, not professional advice. Data from EPA AQS. See our disclaimer.