New data from the Oregon Health Authority indicates some areas around the state, including areas around the Willamette Valley, are at high risk of exposure to a radioactive gas called radon.

OHA's Oregon Radon Awareness Program collected data from test kit manufacturers to understand which areas of the state have the potential for high radon levels.

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They found that Clatskanie, Columbia City, Dundee, Scappoose, Banks, North Plains, Boring, Parkdale, Milton-Freewater and La Grande were among the areas with the highest levels of radon.

The findings also reinforced earlier findings that a large portion of the Portland metro area is at high risk.

“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 and the rocks that came from there are contributing to the higher radon levels that we’re experiencing in the Portland area,” said Curtis Cude with the Oregon Health Authority.

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Radon is a naturally occurring radioactive gas that’s odorless, tasteless and invisible. Radon occurs as uranium naturally decays into radium, which further breaks down into radon gas. It then comes up from the soil and is drawn into buildings where it can build up to dangerous levels.

The Environmental Protection Agency recommends removing radon if levels are 4.0 picocuries per liter of air. Picocuries are a measurement of the radioactivity in a liter of air. But according to the EPA, there is no safe level of radon and long-term exposure poses the most risk.

“If the level is between 2 and 4 picocuries per liter, you ought to consider mitigating and fixing your home regarding radon. Now, if it’s at 4 picocuries per liter or greater, we recommend that you fix your home,” Cude said.

OHA is recommending people take steps to reduce their exposure by conducting their own radon tests in their homes. The best time to test is during the winter months. Test kits can range from $15 to $25. Reducing radon in your home can cost around $1,700.

“It really boils down to the rocks below your home and the condition of your foundation, so the first thing to do is test,” Cude said. “Now, if you find that you do have actionable levels, then you can work with a certified radon mitigation professional and they will come in and do a certain type of procedure that will pull the radon from below your home and then direct it out above your home.”

The EPA estimates that radon is responsible for man than 21,000 lung cancer deaths per year, making it the second-leading cause of lung cancer in the U.S. after cigarette smoking. It's also the leading cause of lung cancer among non-smokers.