State air quality · 2025

North Carolina Air Quality Ranking

Across 34 monitored counties, the typical county in North Carolina posts a median AQI of 39 (Good) and 81.0% of monitored days were rated Good, from EPA AQS.

39
Avg median AQI
81.0%
Good-air days
34
Counties monitored
69%
Cleaner than US states

North Carolina's typical county median AQI is 39 (Good) across 34 monitored counties

According to the U.S. EPA Air Quality System, North Carolina monitors 34 counties with a day-weighted Good-day share of 81.0%. Cleanest: Martin County (100.0% Good). Most polluted: Davidson County (45.8%). These are annual summaries, not live AirNow readings.

Data source EPA Air Quality System (AQS)

Cleaner than US states
North Carolina's day-weighted Good-day share of 81.0% places it cleaner than 69% of US states.
In-state spread
Within North Carolina, Martin County leads at 100.0% Good days while Davidson County sits at 45.8% across 34 monitored counties.
2024→2025 release
North Carolina's Good-day share moved +3.3 points vs the 2024 EPA annual release.
Typical median AQI
Typical median AQI: 39

Verify with AirNow → · EPA AQS →

EPA state monitoring brief

AQS state key NORTH-CAROLINA

North Carolina · 2025 EPA AQS · 34 counties · med AQI 39 · 81.0% Good · Martin→Davidson spread

  • GOOD 39 Median AQI · Good
  • SHARE 81.0% Good-day share
  • COUNT 34 Counties monitored
  • UNH 0 Unhealthy+ days
  • RANK 69% Cleaner than states
  • O3 56.0% Main pollutant share

Good-day share peers

New York81.3%North Carolina (this)81%South Dakota80.8%Kentucky80.6%
Good-day share neighbourhood · nearest ABS peers vs North Carolina

North Carolina's 81.0% Good-day share is cleaner than 69% of monitored US states; Martin and Davidson County bracket the in-state range. Open Martin County →

According to EPA AQS annual summaries on PlainAirData, North Carolina ranks #16 of 52 by day-weighted good-day share (81.0%) and #25 by mean county median AQI (38.9). 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

81.0%

Good-day share in 2025, up 3.3 percentage points vs 2024. County-mean median AQI 39, 1.3 points lower (cleaner) than 2024.

Pollutant mix

Ozone

Main driver on 56.0% of pollutant-assigned days.

  • Ozone 56.0%
  • PM2.5 43.4%
  • PM10 0.5%
  • NO2 0.1%

Monitoring coverage

307

Average monitored days per county in the latest release. 1 of 34 counties sit below the 100-day floor used for cleanest/most-polluted claims.

Counties Monitored

34

Good Days %

81.0%

Avg Median AQI

39

Total Unhealthy Days

0

Best Air Quality

Martin County

Worst Air Quality

Davidson County

Where North Carolina sits nationally

COUNT-derived placement among 52 US states with at least 365 monitored days in the latest county release. North Carolina's day-weighted Good-day share is 81.0% - cleaner than 69% of that comparison set.

North Carolina Good-day share vs. every US state

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

81.0% Cleaner than 69% higher than 69% 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%). Below this entry. 80.0%–85.0%: 13 US states (25%). This entry sits in this band. 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 Carolina have the cleanest and most polluted air?

Cleanest counties in North Carolina

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

  1. 1 Martin County 100%
  2. 2 Lenoir County 97.6%
  3. 3 Caldwell County 97.1%
  4. 4 Hyde County 96.9%
  5. 5 Macon County 96.6%
  6. 6 Carteret County 96.2%
  7. 7 Person County 95.8%
  8. 8 Caswell County 95.1%
  9. 9 Rockingham County 95.1%
  10. 10 Alexander County 93.5%
  11. 11 Granville County 93.3%
  12. 12 Avery County 92.3%

Good-day share · EPA Air Quality System

County Good % Median AQI
Martin 100.0% 31
Lenoir 97.5% 35
Caldwell 97.1% 36
Hyde 96.9% 24
Macon 96.5% 32
Carteret 96.2% 35
Person 95.8% 36
Caswell 95.1% 37
Rockingham 95.1% 38
Alexander 93.5% 38
Granville 93.3% 39
Avery 92.3% 38
Union 91.0% 40
Graham 89.8% 41
Lincoln 89.7% 41
Haywood 89.0% 43
Pitt 88.0% 37
Edgecombe 84.4% 38
Yancey 81.9% 44
Montgomery 81.8% 39
Mitchell 81.5% 31
Swain 81.1% 37
Northampton 78.1% 33
Johnston 77.5% 41
New Hanover 77.0% 41
Guilford 75.1% 41
Rowan 73.7% 43
Buncombe 73.4% 40
Durham 71.8% 42
Catawba 68.9% 42
Cumberland 68.8% 44
Wake 68.5% 43
Forsyth 63.6% 45
Mecklenburg 48.2% 51
Davidson 45.8% 51

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: 34 counties in North Carolina 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.