Metro area air quality · 2025

Walla Walla, WA

Median AQI 40 (Good). 79.5% of monitored days rated Good across this metro's EPA monitoring network.

40
Median AQI
79.5%
Good-air days
0
Unhealthy days
66%
Cleaner than US metros

Walla Walla, WA posted a 2025 median AQI of 40 (Good) with 79.5% Good days

According to the U.S. EPA Air Quality System, the Walla Walla, WA CBSA recorded a median AQI of 40 across 365 monitored days in 2025, with 79.5% rated Good and 0 unhealthy or worse. This is an annual metro comparison, not a live advisory.

Data source EPA Air Quality System (AQS)

Cleaner than US metros
The Walla Walla, WA CBSA's 79.5% Good-day share places it cleaner than 66% of US metros in 2025.
Closest median-AQI peer
Altoona, PA (76.9% Good, median AQI 40) is the closest nationwide median-AQI peer to Walla Walla, WA.
2020–2025 Good-day shift
Walla Walla, WA's Good-day share moved -1.8 points from 2020 to 2025 (median AQI +11).
Median AQI
Median AQI: 40

Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →

The verdict

Walla Walla, WA's peak reading 94 stays in the lower max-AQI tercile on this extract. On the EPA scale the metro runs good, cleaner than the median US metro, with a median AQI of 40 and 79.5% of 365 monitored days in the Good band.

40
median AQI · Good
79.5%
days rated Good
66%
cleaner than US metros
94
worst single reading

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

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • Walla Walla, WA metro's Good-day share fell from 83.9% to 79.5% between the 2024 and 2025 EPA annual releases, a change of -4.4 percentage points.

Compared against 366 monitored days in 2024 and 365 in 2025. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Walla Walla, WA's peak reading 94 stays in the lower max-AQI tercile on this extract. Signature read: peak AQI 94 (low tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 40 over 365 measured days in 2025 (Good / Good). The monitored-day split lands at 290 Good (79%), 75 Moderate (21%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 57; the highest single-day reading hit 94 (Moderate).

Across 2020–2025, Good-day share shifted -1.8 points and median AQI moved +11 (worsening). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Altoona, PA (76.9% good, AQI 40); Beaver Dam, WI (72.3% good, AQI 40); Bismarck, ND (76.7% good, AQI 40).

Understanding AQI →

Air Quality Summary

Median AQI

40

Good

Good Days

79.5%

290 of 365 days

Max AQI

94

Moderate

Health Grade

Good

90th pct: 57

AQI Day Breakdown (2025)

Distribution of 365 monitored days across EPA AQI categories.

Good

290

79%

Moderate

75

21%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Walla Walla, WA metro area's air quality is rated Good based on 79.5% 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 Walla Walla, WA metro compare?

How Walla Walla, WA compares

Good-day share better than typical
Walla Walla, WA 79.5%
Altoona, PA 76.9%
Typical US metro 70.6%
Median AQI better than typical
Walla Walla, WA 40
Altoona, PA 40
Typical US metro 41
Unhealthy days / yr better than typical
Walla Walla, WA 0
Altoona, PA 0
Typical US metro 1

5-Year Air Quality Trend

Air quality is worsening in the Walla Walla, WA metro. Highest Good-day share: 2024 (83.9%, 307 of 366 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 291 66 1 29
2021 286 70 5 40
2022 285 76 1 39
2023 290 71 1 41
2024 307 59 0 38
2025 290 75 0 40

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Walla Walla, WA (40).

Altoona, PA

Median AQI 40 · 76.9% Good-day share

40

Beaver Dam, WI

Median AQI 40 · 72.3% Good-day share

40

Bismarck, ND

Median AQI 40 · 76.7% Good-day share

40

Cape Coral-Fort Myers, FL

Median AQI 40 · 76.4% Good-day share

40

College Station-Bryan, TX

Median AQI 40 · 68.5% Good-day share

40

Fallon, NV

Median AQI 40 · 85.2% Good-day share

40

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Walla Walla, WA's 0 (independent of median AQI).

Aberdeen, SD

0 unhealthy-or-worse days · median AQI 27

27

Aberdeen, WA

0 unhealthy-or-worse days · median AQI 22

22

Adrian, MI

0 unhealthy-or-worse days · median AQI 41

41

Akron, OH

0 unhealthy-or-worse days · median AQI 45

45

Albany, GA

0 unhealthy-or-worse days · median AQI 46

46

Albany, OR

0 unhealthy-or-worse days · median AQI 27

27

Frequently Asked Questions

What is the 90th percentile AQI for Walla Walla, WA? ▼
The 90th percentile AQI for the Walla Walla, WA metro area is 57, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 94 (Moderate).
How many unhealthy air days does Walla Walla, WA have? ▼
In 2025, the Walla Walla, WA metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 94.
What is the air quality in the Walla Walla, WA metro area? ▼
The Walla Walla, WA metro area has a median Air Quality Index (AQI) of 40, rated "Good." 79.5% of monitored days (290 out of 365) had good air quality in 2025.
Is air quality in Walla Walla, WA getting better or worse? ▼
Air quality in the Walla Walla, WA metro is worsening across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2024 at 83.9% (307 of 366 days). Lowest qualifying Good-day share: 2022 at 78.7% (285 of 362 days).
What does AQI 40 mean for health? ▼
An AQI of 40 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
How does Walla Walla, WA compare to other metro areas? ▼
The Walla Walla, WA metro has 79.5% good air days. Similar metros: Altoona, PA (76.9% good), Beaver Dam, WI (72.3% good), Bismarck, ND (76.7% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Walla Walla, WA, 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, Walla Walla, WA · 2020–2025