State air quality · 2025
Alaska Air Quality Ranking
Across 8 monitored counties, the typical county in Alaska posts a median AQI of 20 (Good) and 84.4% of monitored days were rated Good, from EPA AQS.
- 20
- Avg median AQI
- 84.4%
- Good-air days
- 8
- Counties monitored
- 85%
- Cleaner than US states
Alaska's typical county median AQI is 20 (Good) across 8 monitored counties
According to the U.S. EPA Air Quality System, Alaska monitors 8 counties with a day-weighted Good-day share of 84.4%. Cleanest: Kenai Peninsula County (100.0% Good). Most polluted: Fairbanks North Star County (56.4%). These are annual summaries, not live AirNow readings.
Data source EPA Air Quality System (AQS)
- Cleaner than US states
- Alaska's day-weighted Good-day share of 84.4% places it cleaner than 85% of US states.
- In-state spread
- Within Alaska, Kenai Peninsula County leads at 100.0% Good days while Fairbanks North Star County sits at 56.4% across 8 monitored counties.
- 2024→2025 release
- Alaska's Good-day share moved -1.3 points vs the 2024 EPA annual release.
- Typical median AQI
- Typical median AQI: 20
Verify with AirNow → · EPA AQS →
EPA state monitoring brief
AQS state key ALASKA
Alaska · 2025 EPA AQS · 8 counties · med AQI 20 · 84.4% Good · Kenai Peninsula→Fairbanks North Star spread
- GOOD 20 Median AQI · Good
- SHARE 84.4% Good-day share
- COUNT 8 Counties monitored
- UNH 10 Unhealthy+ days
- RANK 85% Cleaner than states
- PM25 65.1% Main pollutant share
Good-day share peers
Alaska's 84.4% Good-day share is cleaner than 85% of monitored US states; Kenai Peninsula and Fairbanks North Star County bracket the in-state range. Open Kenai Peninsula County →
According to EPA AQS annual summaries on PlainAirData, Alaska is #1 of 52 by lowest mean county median AQI (20.3) at good-day share #8 (84.4%) ≠ Hawaii #1 day-weighted good-day share (93.8%, median-AQI #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
84.4%
Good-day share in 2025, down 1.3 percentage points vs 2024. County-mean median AQI 20, within half a point of the 2024 county-mean median.
Pollutant mix
PM2.5
Main driver on 65.1% of pollutant-assigned days.
- PM2.5 65.1%
- Ozone 21.2%
- PM10 13.4%
- CO 0.2%
Monitoring coverage
262
Average monitored days per county in the latest release. 2 of 8 counties sit below the 100-day floor used for cleanest/most-polluted claims.
Counties Monitored
8
Good Days %
84.4%
Avg Median AQI
20
Total Unhealthy Days
10
Best Air Quality
Kenai Peninsula County
Worst Air Quality
Fairbanks North Star County
Where Alaska sits nationally
COUNT-derived placement among 52 US states with at least 365 monitored days in the latest county release. Alaska's day-weighted Good-day share is 84.4% - cleaner than 85% of that comparison set.
Alaska Good-day share vs. every US state
Day-weighted share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release
84.4% Cleaner than 85% higher than 85% of 52 US states
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 Alaska have the cleanest and most polluted air?
Cleanest counties in Alaska
| County | Good % | Median AQI | Max AQI | Unhealthy Days |
|---|---|---|---|---|
| Kenai Peninsula | 100.0% | 9 | 28 | 0 |
| Denali | 99.7% | 33 | 54 | 0 |
| Aleutians East | 99.0% | 11 | 58 | 0 |
| North Slope | 97.7% | 7 | 72 | 0 |
| Matanuska-Susitna | 91.5% | 9 | 141 | 0 |
| Juneau | 84.3% | 23 | 138 | 0 |
| Anchorage | 79.2% | 26 | 110 | 0 |
| Fairbanks North Star | 56.4% | 44 | 190 | 10 |
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: 8 counties in Alaska 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.