State air quality · 2025

North Dakota Air Quality Ranking

Across 9 monitored counties, the typical county in North Dakota posts a median AQI of 38 (Good) and 79.4% of monitored days were rated Good, from EPA AQS.

38
Avg median AQI
79.4%
Good-air days
9
Counties monitored
62%
Cleaner than US states

North Dakota's typical county median AQI is 38 (Good) across 9 monitored counties

According to the U.S. EPA Air Quality System, North Dakota monitors 9 counties with a day-weighted Good-day share of 79.4%. Cleanest: Billings County (82.7% Good). Most polluted: Burke County (76.2%). These are annual summaries, not live AirNow readings.

Data source EPA Air Quality System (AQS)

Cleaner than US states
North Dakota's day-weighted Good-day share of 79.4% places it cleaner than 62% of US states.
In-state spread
Within North Dakota, Billings County leads at 82.7% Good days while Burke County sits at 76.2% across 9 monitored counties.
2024→2025 release
North Dakota's Good-day share moved -1.7 points vs the 2024 EPA annual release.
Typical median AQI
Typical median AQI: 38

Verify with AirNow → · EPA AQS →

EPA state monitoring brief

AQS state key NORTH-DAKOTA

North Dakota · 2025 EPA AQS · 9 counties · med AQI 38 · 79.4% Good · Billings→Burke spread

  • GOOD 38 Median AQI · Good
  • SHARE 79.4% Good-day share
  • COUNT 9 Counties monitored
  • UNH 42 Unhealthy+ days
  • RANK 62% Cleaner than states
  • O3 65.4% Main pollutant share

Good-day share peers

Tennessee80.3%North Dakota (this)79.4%Idaho78.2%West Virginia78.2%
Good-day share neighbourhood · nearest ABS peers vs North Dakota

North Dakota's 79.4% Good-day share is cleaner than 62% of monitored US states; Billings and Burke County bracket the in-state range. Open Billings County →

According to EPA AQS annual summaries on PlainAirData, North Dakota ranks #20 of 52 by day-weighted good-day share (79.4%) and #20 by mean county median AQI (37.9). 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

79.4%

Good-day share in 2025, down 1.7 percentage points vs 2024. County-mean median AQI 38, within half a point of the 2024 county-mean median.

Pollutant mix

Ozone

Main driver on 65.4% of pollutant-assigned days.

  • Ozone 65.4%
  • PM2.5 34.3%
  • PM10 0.2%
  • NO2 0.1%

Monitoring coverage

364

Average monitored days per county in the latest release. Every monitored county clears the 100-day ranking floor.

Counties Monitored

9

Good Days %

79.4%

Avg Median AQI

38

Total Unhealthy Days

42

Best Air Quality

Billings County

Worst Air Quality

Burke County

Where North Dakota sits nationally

COUNT-derived placement among 52 US states with at least 365 monitored days in the latest county release. North Dakota's day-weighted Good-day share is 79.4% - cleaner than 62% of that comparison set.

North Dakota Good-day share vs. every US state

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

79.4% Cleaner than 62% higher than 62% 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 North Dakota have the cleanest and most polluted air?

Cleanest counties in North Dakota

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

  1. 1 Billings County 82.7%
  2. 2 Oliver County 80.8%
  3. 3 McKenzie County 80.8%
  4. 4 Mercer County 80.3%
  5. 5 Dunn County 79.7%
  6. 6 Ward County 79.4%
  7. 7 Burleigh County 78.1%
  8. 8 Cass County 76.2%
  9. 9 Burke County 76.2%

Good-day share · EPA Air Quality System

County Good % Median AQI
Billings 82.7% 38
McKenzie 80.8% 39
Oliver 80.8% 38
Mercer 80.3% 37
Dunn 79.7% 39
Ward 79.4% 36
Burleigh 78.1% 39
Cass 76.2% 37
Burke 76.2% 38

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: 9 counties in North Dakota 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.