Portland Radon Map – 2020 Update, Plus Free Tests (for some)

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Portland Radon rates change. A perennial hot topic in Portland is the influx of Californians, but it’s really the Montana and Idaho migrants that we should be worried about, according to health officials.

Actually, they’re not talking about people, but rocks.

“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 radioactive gas that is drawn into homes and buildings, leading to cancer and other health issues. 

As real estate agents, we do a lot of education about the risks of radon and the importance of testing, and in 2020, it’s more important than ever. Not only are people spending more time in their homes, potentially increasing their exposure to radon, but new public health data has uncovered even more risk areas in Oregon. In addition, more research on short-term tests show that they are not nearly as effective as long-term tests, meaning 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 2020 Radon Risk Map, a large area of Portland including all of Northeast Portland is at a high risk for radon exposure. In total, 11 Portland zip codes are in the red zone for radon.

Portland, Oregon Radon Risk Map from Oregon Health Authority

Click the radon map to access.

Radon Risk Levels – What do they actually mean?

Looking at Portland, we see a lot of red (high risk), more yellow (moderate) and some green (low risk). And scientists didn’t have to dig any holes to find out where the radon-containing rocks are hiding because radon migrates upwards — into homes and buildings, and right 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 tests results are available, the Oregon Health Authority makes an assessment based on the following four factors:

  1. The number of single-family homes with a test result;
  2. 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);
  3. the average test result value for the area; and 
  4. 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)

According to the EPA, radon levels of 4 pCi/L create the same level of risk of dying from lung cancer as dying in a car accident — and that’s for non-smokers. If you smoke, the lung cancer risk at this level of radon exposure goes up to 5x the risk of a fatal car accident. Higher levels of radon create even more certainty that cancer will result. 

Radon levels can be reduced by installing a home mitigation system, 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 an elevated risk for lung cancer, but even in the outdoor air, there’s always some radon present. The EPA reports that the average US outdoor radon level is 0.4 pCi/L.

Free Radon Tests

Note: Some Oregon zip codes don’t have enough test results to be assigned a risk level; if you live in one of these zips OHA will send you a free test kit so that the data can go into future radon maps.

How accurate is the 2020 Portland Radon Map?

Over time, as the Oregon Health Authority gathers more data from home test kits for radon, they are able to improve their risk level assignments, and 2020 was a breakthrough year showing more results than ever before. Fortunately, public awareness about the health hazards of radon is growing, and more homeowners are performing tests and applying mitigation strategies. Over time, however, this could skew the risk level assessment — a large number of homes that mitigate radon will show up as “low” radon homes.

Overall, we don’t recommend that Portland homeowners rely on the map alone to assess their radon risk. For one, it’s not a great map – sorry OHA!  It’s meant to provide an overview for radon risk statewide, and it doesn’t get more accurate as you zoom in (in fact it doesn’t even show the street names bordering the risk areas). 

Fortunately, 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. Here, you can easily 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)

Because radioactive rocks can be anywhere, every home should have a radon test performed, even 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. However, there are some important things to know before you test:

  • Radon levels can fluctuate over time, so it’s best to test in winter.
  • New research shows that the most accurate radon tests are long-term: 90 days or more. 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. 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, radon health risks, and mitigation. Questions about home inspections, and making sure a home is safe before you buy? Contact our Top Buyers’ or Sellers’ agents today!

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