Median AQI
26
Good
Washington · County air quality · 2025
Clallam County, Washington
Median AQI 26 (Good). 88.5% of monitored days rated Good, direct from EPA Air Quality System stations.
- 26
- Median AQI
- 88.5%
- Good-air days
- 0
- Unhealthy days
- 72%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Clallam County's air is good on balance, cleaner than the median US county, a median AQI of 26 with 88.5% of 243 monitored days in the Good band, driven mainly by PM2.5.
- 26
- median AQI · Good
- 88.5%
- days rated Good
- PM2.5
- main pollutant
- 72%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 60.
Data updated July 2026
- Good · 215 d · 88.5%
- Moderate · 28 d · 11.5%
How did Clallam County's air break down in 2025?
Across 243 monitored days, 215 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 60 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 243 days monitored. Median AQI: 26 (Good).
Insights: Clallam County, Washington. EPA monitors recorded a median Air Quality Index of 26 across 243 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 215 (88%) fell in the Good band (AQI 0–50), 28 (12%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 52, while the worst single-day peak hit 60 (Moderate). Residents averaged about 26.5 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (237 days), Ozone (6 days). Across the 2020–2025 trend window, good days shifted by -89 and the median AQI moved -11 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 60, moderate but never Unhealthy. Nearby counties show comparable readings: Adams (94.7% good, AQI 19); Asotin (73.8% good, AQI 35); Benton (88.9% good, AQI 35); Chelan (87.2% good, AQI 27); Clark (89.3% good, AQI 31); Columbia (93.0% good, AQI 37).
Air Quality Summary
Good Days
88.5%
215 of 243 monitored days
13.5pp vs 75% target
Max AQI Recorded
60
Moderate
Health Grade
Good
90th-pct AQI 52
Clallam County, Good days share 88.5%
National avg
Share of monitored days at AQI 0-50 (Good band).
Clallam 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 243 monitored days across EPA AQI categories.
Good
215
88%
Moderate
28
12%
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 Clallam County.
- PM2.5 · 237 days · 97.5%
- Ozone · 6 days · 2.5%
Health Impact Assessment
Good
Clallam County's air quality is rated Good based on 88.5% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 88.5% of monitored days in 2025, with a median AQI of 26. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 237 of 243 monitored days.
5-Year Air Quality Trend
Air quality is improving in Clallam County. Best year: 2024 (321 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 304 | 55 | 1 | 1 | 37 | 368 |
| 2021 | 298 | 67 | 0 | 0 | 37 | 81 |
| 2022 | 272 | 91 | 2 | 0 | 38 | 124 |
| 2023 | 307 | 57 | 1 | 0 | 37 | 101 |
| 2024 | 321 | 45 | 0 | 0 | 36 | 69 |
| 2025 | 215 | 28 | 0 | 0 | 26 | 60 |
How does Clallam County compare?
How Clallam County compares
Good-day share better than US avg
Clallam County 88.5%
Adams County, Washington 94.7%
US average 76.5%
Median AQI better than US avg
Clallam County 26
Adams County, Washington 19
US average 38
Unhealthy days / yr about average
Clallam County 0
Adams County, Washington 0
US average 0
Other Counties in Washington
Air quality comparison for nearby counties in Washington.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Clallam County.
Ford County, Kansas
AQI 26 · 89.4% good
Grant County, Washington
AQI 26 · 89.7% good
Harney County, Oregon
AQI 26 · 70.7% good
Taney County, Missouri
AQI 26 · 100.0% good
Thurston County, Washington
AQI 26 · 98.1% good
Wyoming County, Pennsylvania
AQI 26 · 83.1% good
What Clallam 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 26 means for exposure. Health guidance
- See how Clallam County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Clallam County with its Washington neighbours before drawing a conclusion about the region. All of Washington
Based on 243 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 Clallam County, Washington? ▼
Clallam County has a median Air Quality Index (AQI) of 26, rated "Good." 88.5% of monitored days (215 out of 243) had good air quality in 2025.
What is the main pollutant in Clallam County? ▼
The primary pollutant in Clallam County is Fine Particles (PM2.5), which was the main AQI driver on 237 days (98% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Clallam County have? ▼
In 2025, Clallam County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 60.
Is the air quality in Clallam County getting better or worse? ▼
Air quality in Clallam County is improving based on 5-year trends (2020-2025). Best year: 2024 with 321 good days. Worst year: 2025 with 215 good days.
What does AQI 26 mean for health? ▼
Clallam County's median AQI of 26 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 Clallam County compare to other counties in Washington? ▼
Clallam County has 88.5% good air days. Nearby counties in Washington: Adams (94.7% good), Asotin (73.8% good), Benton (88.9% good), Chelan (87.2% good), Clark (89.3% good), Columbia (93.0% good).
What is the 90th percentile AQI in Clallam County? ▼
The 90th percentile AQI for Clallam County is 52, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 60 (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.