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Radon in Portland, Oregon

Portland, Oregon spans 3 counties, Clackamas County, Multnomah County and Washington County. Radon data is published by county, so this page sets their figures side by side.

OregonAbout 635,109 people

What this means for you

  • Your area: Portland lies in 3 counties. EPA rates Clackamas County Zone 3, Multnomah County Zone 2 and Washington County Zone 2, where Zone 1 is the highest of its three radon zones. Zones are predictions for whole counties, and homes with elevated levels occur in all three zones.
  • Local tests: For 2023, the share of radon tests reported to CDC that were at or above 4 pCi/L was 15.9% in Clackamas County (321 tests), 27.8% in Multnomah County (792 tests) and 11.4% in Washington County (396 tests). EPA's action level is 4 pCi/L.
  • Your home: The only way to know your home’s level is to test it.
How to testFind a certified tester

pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.

Portland, What is published

What is published for Portland

Information:

Radon data is published by county, not by city

Radon data is published by county, not by city. EPA assigns radon zones to counties, and CDC publishes radon test figures by county. Neither publishes a figure for Portland, so every radon figure on this page belongs to a county and is labelled with it. Only a test tells you about one home.

Each county has its own CDC test figures, shown below side by side. About 635,109 people live in Portland.

Portland, Counties

Portland's counties, side by side

Measured

Each county's own EPA zone and its own published CDC figures for 2023, the newest period any of them has. A county without a figure for that period is shown without one, never with a figure from another year.

  • Clackamas County
    EPA zone
    Zone 3: Lower predicted potential
    At or above 4 pCi/L
    15.9%
    Median result
    1.6 pCi/L
    Tests reported
    321 tests
    Annual years on file
    10
  • Multnomah County
    EPA zone
    Zone 2: Moderate predicted potential
    At or above 4 pCi/L
    27.8%
    Median result
    2.0 pCi/L
    Tests reported
    792 tests
    Annual years on file
    10
  • Washington County
    EPA zone
    Zone 2: Moderate predicted potential
    At or above 4 pCi/L
    11.4%
    Median result
    1.3 pCi/L
    Tests reported
    396 tests
    Annual years on file
    10
The counties Portland lies in, each with its own EPA zone and its own published CDC figures for 2023
CountyEPA zoneReported tests at or above 4 pCi/LMedian reported resultTests reportedAnnual years on file
Clackamas CountyZone 3: Lower predicted potential15.9%1.6 pCi/L321 tests10
Multnomah CountyZone 2: Moderate predicted potential27.8%2.0 pCi/L792 tests10
Washington CountyZone 2: Moderate predicted potential11.4%1.3 pCi/L396 tests10

The median reported pre-mitigation result for 2023 was 1.6 pCi/L in Clackamas County, 2.0 pCi/L in Multnomah County and 1.3 pCi/L in Washington County.

CDC counts radon tests that were reported to it, not homes, and figures from few tests can swing widely from year to year. Each county’s report has its full history.

Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2023.

Portland, Local resources

Local resources for Portland

Who to ask in Oregon: the state's radon program, test kits and professionals.

Oregon Radon Awareness Program

Oregon Health Authority

Oregon’s radon program answers questions about testing, mitigation and the rules where you live.

Email
Radon.program@dhsoha.state.or.us
Visit the program's page(opens in a new tab)

Test kits

The program says: Oregon Radon Awareness Program provides a FREE short-term radon test kit to those living in areas of Oregon where little radon testing has been done.

Free and low-cost kitsCompare kits

Radon professionals

Radon testers and mitigators in Oregon, each with how its listing was checked.

Professionals in Oregon

Portland, Questions

Questions about radon in Portland

What radon zone is Portland in?

EPA's Map of Radon Zones classifies counties, not cities. Multnomah County and Washington County are in Zone 2 (moderate predicted potential); Clackamas County is in Zone 3 (lower predicted potential). The counties Portland lies in do not share one zone, so no single zone is given for Portland. A zone is a prediction for a whole county and never tells you the level in one home.

How many radon tests come back high in Portland's counties?

For 2023, the share of radon tests reported to CDC that were at or above 4 pCi/L was 15.9% in Clackamas County (321 tests), 27.8% in Multnomah County (792 tests) and 11.4% in Washington County (396 tests). Each is that county's own figure, counting tests reported to CDC, not homes. Radon411 does not average or combine them into a figure for the city.

Should I test my home in Portland?

Yes. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. How to test a home.

The answers use the published figures of Clackamas County, Multnomah County and Washington County, the counties Portland lies in.

Portland, Keep reading

Keep reading

Portland / Next steps

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