Metro area air quality · 2025

Hermiston-Pendleton, OR

Median AQI 39 (Good). 79.6% of monitored days rated Good across this metro's EPA monitoring network.

39
Median AQI
79.6%
Good-air days
0
Unhealthy days
62%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 181 monitored days. EPA AQS →

The verdict

The Hermiston-Pendleton, OR metro runs good on the EPA scale, cleaner than the median US metro, a median AQI of 39 with 79.6% of 181 monitored days in the Good band.

39
median AQI · Good
79.6%
days rated Good
62%
cleaner than US metros
79
worst single reading

No day crossed into the Unhealthy tier across the metro's monitors in 2025.

Insights: Hermiston-Pendleton, OR metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 39 over 181 measured days in 2025, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 144 Good days (80%), 37 Moderate (20%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 57 while the highest single-day reading hit 79 (Moderate). Metro residents averaged roughly 23.9 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -129 and the median AQI moved +1 points, which classifies the multi-year trajectory as improving. The metro avoided any Unhealthy-tier days entirely, an outcome that typically reflects favorable wind patterns, lower industrial density, or effective regional emission controls. Metros with comparable AQI profiles include Beaver Dam, WI (76.4% good, AQI 39); Bennington, VT (82.9% good, AQI 39); Billings, MT (86.7% good, AQI 39).

Air Quality Summary

Median AQI

39

Good

Good Days

79.6%

144 of 181 days

Max AQI

79

Moderate

Health Grade

Good

90th pct: 57

AQI Day Breakdown (2025)

Distribution of 181 monitored days across EPA AQI categories.

Good

144

80%

Moderate

37

20%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Hermiston-Pendleton, OR metro area's air quality is rated Good based on 79.6% good air days. No unhealthy air days were recorded in 2025.

Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.

How does the Hermiston-Pendleton, OR metro compare?

How Hermiston-Pendleton, OR compares

Good-day share better than US avg
Hermiston-Pendleton, OR 79.6%
Beaver Dam, WI 76.4%
US average 71.3%
Median AQI better than US avg
Hermiston-Pendleton, OR 39
Beaver Dam, WI 39
US average 41
Unhealthy days / yr better than US avg
Hermiston-Pendleton, OR 0
Beaver Dam, WI 0
US average 1

5-Year Air Quality Trend

Air quality is improving in the Hermiston-Pendleton, OR metro. Best year: 2020 (273 good days).

Year Good Moderate Unhealthy Median AQI
2020 273 85 1 38
2021 265 92 2 38
2022 244 118 0 39
2023 259 103 1 42
2024 272 90 0 38
2025 144 37 0 39

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Hermiston-Pendleton, OR.

Beaver Dam, WI

AQI 39 · 76.4% good

39

Bennington, VT

AQI 39 · 82.9% good

39

Billings, MT

AQI 39 · 86.7% good

39

Blacksburg-Christiansburg-Radford, VA

AQI 39 · 92.4% good

39

Brainerd, MN

AQI 39 · 84.4% good

39

Brunswick, GA

AQI 39 · 81.9% good

39

More Air Quality Data

Explore EPA air quality rankings and guides across U.S. metros and counties.

Cleanest Metro Areas

U.S. metros ranked by their share of Good air-quality days.

Worst Air Quality

Counties and metros with the most unhealthy air days.

All Metro Areas

Annual AQI by CBSA for every monitored U.S. metro area.

Best and Worst City Air

What drives urban air quality and how metro areas compare.

Air Quality Guides

Frequently Asked Questions

What is the air quality in the Hermiston-Pendleton, OR metro area? ▼
The Hermiston-Pendleton, OR metro area has a median Air Quality Index (AQI) of 39, rated "Good." 79.6% of monitored days (144 out of 181) had good air quality in 2025.
How many unhealthy air days does Hermiston-Pendleton, OR have? ▼
In 2025, the Hermiston-Pendleton, OR metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 79.
Is air quality in Hermiston-Pendleton, OR getting better or worse? ▼
Air quality in the Hermiston-Pendleton, OR metro is improving based on 5-year trends (2020-2025). Best year: 2020 with 273 good days. Worst year: 2025 with 144 good days.
What does AQI 39 mean for health? ▼
An AQI of 39 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
What is the 90th percentile AQI for Hermiston-Pendleton, OR? ▼
The 90th percentile AQI for the Hermiston-Pendleton, OR metro area is 57, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 79 (Moderate).
How does Hermiston-Pendleton, OR compare to other metro areas? ▼
The Hermiston-Pendleton, OR metro has 79.6% good air days. Similar metros: Beaver Dam, WI (76.4% good), Bennington, VT (82.9% good), Billings, MT (86.7% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2025. See our methodology for how AQI, median, and coverage figures are computed.

Read our methodology , how this data is sourced, computed, and verified.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary files (metro-level) · 2020–2025

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.