Median AQI
27
Good
Oregon · County air quality · 2025
Clackamas County, Oregon
Median AQI 27 (Good). 93.9% of monitored days rated Good, direct from EPA Air Quality System stations.
- 27
- Median AQI
- 93.9%
- Good-air days
- 0
- Unhealthy days
- 85%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Clackamas County's air is good on balance, cleaner than most US counties, a median AQI of 27 with 93.9% of 180 monitored days in the Good band, driven mainly by PM2.5.
- 27
- median AQI · Good
- 93.9%
- days rated Good
- PM2.5
- main pollutant
- 85%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 90.
Data updated July 2026
- Good · 169 d · 93.9%
- Moderate · 11 d · 6.1%
How did Clackamas County's air break down in 2025?
Across 180 monitored days, 169 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 90 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 180 days monitored. Median AQI: 27 (Good).
Insights: Clackamas County, Oregon. EPA monitors recorded a median Air Quality Index of 27 across 180 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 169 (94%) fell in the Good band (AQI 0–50), 11 (6%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 46, while the worst single-day peak hit 90 (Moderate). Residents averaged about 28.2 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (123 days), Ozone (57 days). Across the 2020–2025 trend window, good days shifted by -69 and the median AQI moved -6 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 90, moderate but never Unhealthy. Nearby counties show comparable readings: Baker (89.0% good, AQI 25); Columbia (96.7% good, AQI 25); Crook (80.7% good, AQI 24); Deschutes (93.4% good, AQI 22); Grant (66.7% good, AQI 34); Harney (70.7% good, AQI 26).
Air Quality Summary
Good Days
93.9%
169 of 180 monitored days
18.9pp vs 75% target
Max AQI Recorded
90
Moderate
Health Grade
Excellent
90th-pct AQI 46
Clackamas County, Good days share 93.9%
National avg
Share of monitored days at AQI 0-50 (Good band).
Clackamas County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 180 monitored days across EPA AQI categories.
Good
169
94%
Moderate
11
6%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Clackamas County.
- PM2.5 · 123 days · 68.3%
- Ozone · 57 days · 31.7%
Health Impact Assessment
Excellent
Clackamas County's air quality is rated Excellent based on 93.9% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 93.9% of monitored days in 2025, with a median AQI of 27. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 123 of 180 monitored days.
5-Year Air Quality Trend
Air quality is improving in Clackamas County. Best year: 2024 (325 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 238 | 25 | 3 | 2 | 33 | 481 |
| 2021 | 320 | 33 | 0 | 1 | 31 | 161 |
| 2022 | 286 | 73 | 3 | 2 | 33 | 168 |
| 2023 | 304 | 57 | 4 | 0 | 34 | 125 |
| 2024 | 325 | 34 | 6 | 0 | 30 | 127 |
| 2025 | 169 | 11 | 0 | 0 | 27 | 90 |
How does Clackamas County compare?
How Clackamas County compares
Good-day share better than US avg
Clackamas County 93.9%
Baker County, Oregon 89.0%
US average 76.5%
Median AQI better than US avg
Clackamas County 27
Baker County, Oregon 25
US average 38
Unhealthy days / yr about average
Clackamas County 0
Baker County, Oregon 0
US average 0
Other Counties in Oregon
Air quality comparison for nearby counties in Oregon.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Clackamas County.
Chelan County, Washington
AQI 27 · 87.2% good
Silver Bow County, Montana
AQI 27 · 82.9% good
Stevens County, Washington
AQI 27 · 81.1% good
Clallam County, Washington
AQI 26 · 88.5% good
Delta County, Colorado
AQI 28 · 88.0% good
Ford County, Kansas
AQI 26 · 89.4% good
What Clackamas County's air means for you
The air here stays in the breathable range year-round, with PM2.5 the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 27 means for exposure. Health guidance
- See how Clackamas County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Clackamas County with its Oregon neighbours before drawing a conclusion about the region. All of Oregon
Based on 180 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Clackamas County, Oregon? ▼
Clackamas County has a median Air Quality Index (AQI) of 27, rated "Good." 93.9% of monitored days (169 out of 180) had good air quality in 2025.
What is the main pollutant in Clackamas County? ▼
The primary pollutant in Clackamas County is Fine Particles (PM2.5), which was the main AQI driver on 123 days (68% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Clackamas County have? ▼
In 2025, Clackamas County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 90.
Is the air quality in Clackamas County getting better or worse? ▼
Air quality in Clackamas County is improving based on 5-year trends (2020-2025). Best year: 2024 with 325 good days. Worst year: 2025 with 169 good days.
What does AQI 27 mean for health? ▼
Clackamas County's median AQI of 27 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Clackamas County compare to other counties in Oregon? ▼
Clackamas County has 93.9% good air days. Nearby counties in Oregon: Baker (89.0% good), Columbia (96.7% good), Crook (80.7% good), Deschutes (93.4% good), Grant (66.7% good), Harney (70.7% good).
What is the 90th percentile AQI in Clackamas County? ▼
The 90th percentile AQI for Clackamas County is 46, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 90 (Moderate).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer.
Every figure on PlainAir 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.