Olympia-Tumwater, WA

EPA AQS → · NOAA →

Metro area air quality from EPA Air Quality System (2024). 362 days monitored. Median AQI: 26 (Good).

Insights: Olympia-Tumwater, WA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 26 over 362 measured days in 2024, which corresponds to a Good band and a Excellent metro-wide health grade. The monitored-day split lands at 338 Good days (93%), 24 Moderate (7%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 44 while the highest single-day reading hit 85 (Moderate). Metro residents averaged roughly 28.0 clean-air days per 30-day window across the reporting year.

Across the 2020–2024 trend window, good days shifted by +22 and the median AQI moved -2 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 Anchorage, AK (77.6% good, AQI 26); Branson, MO (88.9% good, AQI 26); Dodge City, KS (86.6% good, AQI 26).

Air Quality Summary

Median AQI

26

Good

Good Days

93.4%

338 of 362 days

Max AQI

85

Moderate

Health Grade

Excellent

90th pct: 44

AQI Day Breakdown (2024)

Distribution of 362 monitored days across EPA AQI categories.

Good

338

93%

Moderate

24

7%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Excellent

The Olympia-Tumwater, WA metro area's air quality is rated Excellent based on 93.4% good air days. No unhealthy air days were recorded in 2024.

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

5-Year Air Quality Trend

Air quality is improving in the Olympia-Tumwater, WA metro. Best year: 2024 (338 good days).

Year Good Moderate Unhealthy Median AQI
2020 316 43 3 28
2021 309 20 0 19
2022 309 36 2 28
2023 327 31 0 28
2024 338 24 0 26

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Olympia-Tumwater, WA.

Anchorage, AK

AQI 26 · 77.6% good

26

Branson, MO

AQI 26 · 88.9% good

26

Dodge City, KS

AQI 26 · 86.6% good

26

Moses Lake, WA

AQI 26 · 86.9% good

26

Mount Vernon-Anacortes, WA

AQI 26 · 97.5% good

26

Albany, OR

AQI 25 · 87.4% good

25

Related Environmental & Health Data

Explore related data for the Olympia-Tumwater, WA area from other federal sources.

🏭

PlainEnviro — EPA Facilities

EPA environmental compliance data for regulated facilities. 5-year violation trends.

🏥

PlainHealth — Mortality Data

CDC NCHS leading causes of death. 19 years of mortality data by cause.

🌡️

PlainClimate — Climate Normals

NOAA 30-year climate normals. Temperature, precipitation, humidity.

⚠️

PlainHazard — Natural Disasters

FEMA disaster declarations. Wildfire, flood, and storm history affecting air quality. FEMA.gov →

Air Quality Guides

Learn more about air quality monitoring, pollutants, and health impacts.

Understanding AQI

What each AQI level means and who is most at risk.

Best & Worst City Air Quality

Metro area air quality rankings and what drives urban pollution.

Health Effects of Air Pollution

How PM2.5 and ozone exposure affects respiratory and cardiovascular health.

Frequently Asked Questions

What is the air quality in the Olympia-Tumwater, WA metro area? ▼
The Olympia-Tumwater, WA metro area has a median Air Quality Index (AQI) of 26, rated "Good." 93.4% of monitored days (338 out of 362) had good air quality in 2024.
How many unhealthy air days does Olympia-Tumwater, WA have? ▼
In 2024, the Olympia-Tumwater, WA metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 85.
Is air quality in Olympia-Tumwater, WA getting better or worse? ▼
Air quality in the Olympia-Tumwater, WA metro is improving based on 5-year trends (2020-2024). Best year: 2024 with 338 good days. Worst year: 2022 with 309 good days.
What does AQI 26 mean for health? ▼
An AQI of 26 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 Olympia-Tumwater, WA? ▼
The 90th percentile AQI for the Olympia-Tumwater, WA metro area is 44, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 85 (Moderate).
How does Olympia-Tumwater, WA compare to other metro areas? ▼
The Olympia-Tumwater, WA metro has 93.4% good air days. Similar metros: Anchorage, AK (77.6% good), Branson, MO (88.9% good), Dodge City, KS (86.6% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2024. The AQS collects ambient air monitoring data from state, local, and tribal monitoring agencies across the United States.

Metrics: Air Quality Index (AQI) is calculated using EPA-standard breakpoints for six criteria pollutants: PM2.5, PM10, Ozone, NO2, CO, and SO2. Median AQI, max AQI, and 90th percentile AQI are computed from daily measurements. Good days percentage reflects days with AQI 0–50.

Coverage: 501 metro areas (Core Based Statistical Areas). Only metros with active monitoring stations are included. Unmonitored areas are not represented.

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

Source: U.S. EPA — AirNow / AQS Air Quality Index readings and pollutant concentrations · 2025