The Dalles, OR

EPA AQS → · NOAA →

Metro area air quality from EPA Air Quality System (2024). 364 days monitored. Median AQI: 23 (Good).

Insights: The Dalles, OR metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 23 over 364 measured days in 2024, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 317 Good days (87%), 47 Moderate (13%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 52 while the highest single-day reading hit 93 (Moderate). Metro residents averaged roughly 26.1 clean-air days per 30-day window across the reporting year.

Across the 2020–2024 trend window, good days shifted by +10 and the median AQI moved -1 points, which classifies the multi-year trajectory as stable. 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 Elko, NV (87.1% good, AQI 23); Ellensburg, WA (87.4% good, AQI 23); La Grande, OR (82.8% good, AQI 23).

Air Quality Summary

Median AQI

23

Good

Good Days

87.1%

317 of 364 days

Max AQI

93

Moderate

Health Grade

Good

90th pct: 52

AQI Day Breakdown (2024)

Distribution of 364 monitored days across EPA AQI categories.

Good

317

87%

Moderate

47

13%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The The Dalles, OR metro area's air quality is rated Good based on 87.1% 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 stable in the The Dalles, OR metro. Best year: 2024 (317 good days).

Year Good Moderate Unhealthy Median AQI
2020 307 45 0 24
2021 287 30 1 22
2022 161 0 0 16
2023 244 40 2 27
2024 317 47 0 23

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to The Dalles, OR.

Elko, NV

AQI 23 · 87.1% good

23

Ellensburg, WA

AQI 23 · 87.4% good

23

La Grande, OR

AQI 23 · 82.8% good

23

Lubbock, TX

AQI 23 · 92.2% good

23

Twin Falls, ID

AQI 23 · 76.1% good

23

Aberdeen, SD

AQI 24 · 85.7% good

24

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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 The Dalles, OR metro area? ▼
The The Dalles, OR metro area has a median Air Quality Index (AQI) of 23, rated "Good." 87.1% of monitored days (317 out of 364) had good air quality in 2024.
How many unhealthy air days does The Dalles, OR have? ▼
In 2024, the The Dalles, OR metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 93.
Is air quality in The Dalles, OR getting better or worse? ▼
Air quality in the The Dalles, OR metro is stable based on 5-year trends (2020-2024). Best year: 2024 with 317 good days. Worst year: 2022 with 161 good days.
What does AQI 23 mean for health? ▼
An AQI of 23 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 The Dalles, OR? ▼
The 90th percentile AQI for the The Dalles, OR metro area is 52, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 93 (Moderate).
How does The Dalles, OR compare to other metro areas? ▼
The The Dalles, OR metro has 87.1% good air days. Similar metros: Elko, NV (87.1% good), Ellensburg, WA (87.4% good), La Grande, OR (82.8% 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