Portland, Oregon Radon Map – Plus Free Tests (for some).

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Updated 08/2024.

“In the Portland metropolitan area, a lot of the rocks and soil underneath the Willamette Valley were carried down from parts of Idaho and Montana,” said an Oregon Health Authority official quoted by OPB. These long-ago geological travelers carry radon, a dangerous and often deadly gas.

People are spending more time in their homes, potentially increasing their radon exposure, and new public health data has uncovered even more risk areas in Oregon.

More research on short-term tests also shows that single radon tests are not nearly as effective as long-term tests. This means that the radon test you received when you bought your home is good, but to be completely safe, you might want to do more (more on that in the last section of this article).

According to the Oregon Health Authority’s Radon Risk Map, large areas of Portland, including all of Northeast Portland, are at a high risk for radon exposure. In total, 11 Portland zip codes are in the red zone for radon.

Click the radon map to access.

Looking at Portland, we see a lot of red (high risk), more yellow (moderate), and some green (low risk), but how do they know? Scientists didn’t have to dig any holes to find where the radon-containing rocks are hiding because radon migrates upwards — into homes and buildings and directly through foundations and walls. So, risk levels are assigned to areas based on tests that check for these invisible, radioactive particles.

For each zip code in the state where an adequate number of test results are available, the Oregon Health Authority makes an assessment based on the following four factors:

●       The number of single-family homes with a test result

●       the maximum test result value in the zip code area (Radon levels can vary widely from address to address, which is why all homes need to get their own test done and retest every 2 years)

●       the average test result value for the area

●   the percent of locations within the area that had a test result of more than 4 piC/L (Picocuries per Liter. A “curie” is a unit used to measure radioactivity, named after Marie Curie, the scientist who discovered radium)

You can get a breakdown of the risk levels of individual zip codes, whether in Portland or elsewhere in Oregon, by going to the OHA’s test results summary table. Simply look up your zip code and find out whether it’s red, yellow or green.

Check the Radon Map, then Test (Even for “Green” Zones)

The reason for fluctuating radon readings in any given area is that radon levels can be affected by a number of things, like radioactive rocks, wind, ground pressure, shifting soil, cold weather, local construction, and earthquakes. Being aware of radon levels in and near your home is important, as radon is responsible for about 21,000 lung cancer deaths each year from radon exposure, according to the Environmental Protection Agency (EPA), with about 2,900 of those deaths occurring in people who have never smoked.

Because radioactive rocks can be anywhere, every home should have a radon test performed, even if the home’s zip code is “green”. However, radon testing is not currently required under Oregon law as part of the home sale inspection. That means it’s up to buyers to request the test as part of the home inspection.

■   New research shows that the most accurate radon tests are long-term: 90 days or more. They account for daily fluctuations and provide a more precise average. A best practice for home buyers is to get a 48-hour test done as part of the home inspection, then retest using a longer-term test the following winter before undertaking mitigation (or considering yourself safe!)

■       Repeat the radon test every two years. The definition of a radioactive material is that it is unstable — radon-containing rocks may fluctuate in the amount of radon they release.

■   New homes built in Portland (in fact a wider area: all of Baker, Clackamas, Hood River, Multnomah, Polk, Washington and Yamhill counties) since 2013 are required to use Radon Resistant New Construction (RRNC). However, OHA still recommends that new homes be tested for radon.

Visit the Oregon Health Authority website for more information about testing your Portland home for radon, health risks, and mitigation.

Some Oregon zip codes don’t have enough test results to assign a risk level; if you live in one of these zip codes, OHA will send you a free test kit so that the data will be included in future radon maps.

Hire a State-certified, radon-qualified contractorThe Oregon Health Authority (OHA) has a list of Oregon companies that have at least one radon specialist on staff. You can also search the National Radon Proficiency Program’s directory or do a search on the National Radon Safety Board’s website.

Install a radon mitigation system—The EPA claims that some radon mitigation systems can reduce the radon in a home up to 99% and that most homes can be fixed for about the same cost as other common household repairs.

Certain fixes can reduce radon levels inside your home, but according to Consumer Reports, most homeowners with high radon levels don’t get it down below 2 pCi/L. At this level, there’s still a slightly elevated risk for lung cancer.

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