State air quality · 2025

Oregon Air Quality Ranking

Across 21 monitored counties, the typical county in Oregon posts a median AQI of 32 (Good) and 76.9% of monitored days were rated Good, from EPA AQS.

32
Avg median AQI
76.9%
Good-air days
21
Counties monitored
54%
Cleaner than US states

Oregon's typical county median AQI is 32 (Good) across 21 monitored counties

According to the U.S. EPA Air Quality System, Oregon monitors 21 counties with a day-weighted Good-day share of 76.9%. Cleanest: Columbia County (92.9% Good). Most polluted: Lane County (56.4%). These are annual summaries, not live AirNow readings.

Data source EPA Air Quality System (AQS)

Cleaner than US states
Oregon's day-weighted Good-day share of 76.9% places it cleaner than 54% of US states.
In-state spread
Within Oregon, Columbia County leads at 92.9% Good days while Lane County sits at 56.4% across 21 monitored counties.
2024→2025 release
Oregon's Good-day share moved -0.1 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 OREGON

Oregon · 2025 EPA AQS · 21 counties · med AQI 32 · 76.9% Good · Columbia→Lane spread

  • GOOD 32 Median AQI · Good
  • SHARE 76.9% Good-day share
  • COUNT 21 Counties monitored
  • UNH 5 Unhealthy+ days
  • RANK 54% Cleaner than states
  • PM25 86.7% Main pollutant share

Good-day share peers

Oregon (this)76.9%Minnesota76.8%Connecticut76.7%Nevada76.5%
Good-day share neighbourhood · nearest ABS peers vs Oregon

Oregon's 76.9% Good-day share is cleaner than 54% of monitored US states; Columbia and Lane County bracket the in-state range. Open Columbia County →

According to EPA AQS annual summaries on PlainAirData, Oregon ranks #24 of 52 by day-weighted good-day share (76.9%) and #9 by mean county median AQI (32.0). 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

76.9%

Good-day share in 2025, down 0.1 percentage points vs 2024. County-mean median AQI 32, within half a point of the 2024 county-mean median.

Pollutant mix

PM2.5

Main driver on 86.7% of pollutant-assigned days.

  • PM2.5 86.7%
  • Ozone 13.2%
  • 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

21

Good Days %

76.9%

Avg Median AQI

32

Total Unhealthy Days

5

Best Air Quality

Columbia County

Worst Air Quality

Lane County

Where Oregon sits nationally

COUNT-derived placement among 52 US states with at least 365 monitored days in the latest county release. Oregon's day-weighted Good-day share is 76.9% - cleaner than 54% of that comparison set.

Oregon Good-day share vs. every US state

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

76.9% Cleaner than 54% higher than 54% 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 Oregon have the cleanest and most polluted air?

Cleanest counties in Oregon

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

  1. 1 Columbia County 92.9%
  2. 2 Deschutes County 89.3%
  3. 3 Clackamas County 87.6%
  4. 4 Wasco County 86.3%
  5. 5 Wallowa County 85.2%
  6. 6 Union County 84.4%
  7. 7 Baker County 83.3%
  8. 8 Lake County 80.5%
  9. 9 Linn County 80%
  10. 10 Marion County 80%
  11. 11 Washington County 79.2%
  12. 12 Multnomah County 77.5%

Good-day share · EPA Air Quality System

County Good % Median AQI
Columbia 92.9% 27
Deschutes 89.3% 23
Clackamas 87.6% 31
Wasco 86.3% 25
Wallowa 85.2% 26
Union 84.4% 27
Baker 83.3% 29
Lake 80.5% 26
Linn 80.0% 27
Marion 80.0% 35
Washington 79.2% 36
Multnomah 77.5% 37
Jefferson 74.0% 28
Crook 72.9% 28
Harney 71.5% 28
Umatilla 71.2% 41
Josephine 68.2% 33
Jackson 66.3% 43
Klamath 64.4% 38
Grant 63.2% 37
Lane 56.4% 46

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: 21 counties in Oregon 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.