State air quality · 2025

Vermont Air Quality Ranking

Across 4 monitored counties, the typical county in Vermont posts a median AQI of 32 (Good) and 83.8% of monitored days were rated Good, from EPA AQS.

32
Avg median AQI
83.8%
Good-air days
4
Counties monitored
81%
Cleaner than US states

Vermont's typical county median AQI is 32 (Good) across 4 monitored counties

According to the U.S. EPA Air Quality System, Vermont monitors 4 counties with a day-weighted Good-day share of 83.8%. Cleanest: Windham County (92.0% Good). Most polluted: Rutland County (77.8%). These are annual summaries, not live AirNow readings.

Data source EPA Air Quality System (AQS)

Cleaner than US states
Vermont's day-weighted Good-day share of 83.8% places it cleaner than 81% of US states.
In-state spread
Within Vermont, Windham County leads at 92.0% Good days while Rutland County sits at 77.8% across 4 monitored counties.
2024→2025 release
Vermont's Good-day share moved -3.5 points vs the 2024 EPA annual release.
Typical median AQI
Typical median AQI: 32

Verify with AirNow → · EPA AQS →

EPA state monitoring brief

AQS state key VERMONT

Vermont · 2025 EPA AQS · 4 counties · med AQI 32 · 83.8% Good · Windham→Rutland spread

  • GOOD 32 Median AQI · Good
  • SHARE 83.8% Good-day share
  • COUNT 4 Counties monitored
  • UNH 1 Unhealthy+ days
  • RANK 81% Cleaner than states
  • O3 68.5% Main pollutant share

Good-day share peers

Alaska84.4%Puerto Rico84%Vermont (this)83.8%Massachusetts83.1%
Good-day share neighbourhood · nearest ABS peers vs Vermont

Vermont's 83.8% Good-day share is cleaner than 81% of monitored US states; Windham and Rutland County bracket the in-state range. Open Windham County →

According to EPA AQS annual summaries on PlainAirData, Vermont ranks #10 of 52 by day-weighted good-day share (83.8%) and #8 by mean county median AQI (31.8). 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

83.8%

Good-day share in 2025, down 3.5 percentage points vs 2024. County-mean median AQI 32, 1.3 points higher (worse) than 2024.

Pollutant mix

Ozone

Main driver on 68.5% of pollutant-assigned days.

  • Ozone 68.5%
  • PM2.5 31.5%

Monitoring coverage

297

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

Counties Monitored

4

Good Days %

83.8%

Avg Median AQI

32

Total Unhealthy Days

1

Best Air Quality

Windham County

Worst Air Quality

Rutland County

Where Vermont sits nationally

COUNT-derived placement among 52 US states with at least 365 monitored days in the latest county release. Vermont's day-weighted Good-day share is 83.8% - cleaner than 81% of that comparison set.

Vermont Good-day share vs. every US state

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

83.8% Cleaner than 81% higher than 81% 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 Vermont have the cleanest and most polluted air?

Cleanest counties in Vermont

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

  1. 1 Windham County 92%
  2. 2 Chittenden County 87.7%
  3. 3 Bennington County 83.6%
  4. 4 Rutland County 77.8%

Good-day share · EPA Air Quality System

County Good % Median AQI
Windham 92.0% 15
Chittenden 87.7% 38
Bennington 83.6% 37
Rutland 77.8% 37

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: 4 counties in Vermont 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.