Where does it come from? Thousands of years ago a series of enormous floods carried granite rocks and soil from western Montana and northern Idaho down the Columbia River Gorge, into the Willamette Valley. This granite debris covers much of the Portland/Vancouver metropolitan area. This granite contains uranium, which decays and produces radon gas.
Why is radon unhealthy? The by-products of radon gas can attach themselves to the lung lining, and release radioactive alpha particles that irritate and can mutate lung cells. This damage can lead to lung cancer. In fact, health agencies consider radon to be the second leading cause of lung cancer in the United States, second only to cigarette smoking.
What neighborhoods have the highest levels? Elevated levels of radon have been found in communities from Hood River to Hillsboro, and from Vancouver to Eugene. In fact, most areas up to about 400 feet above sea level in the Willamette and Columbia River valleys have the potential for high radon levels. Radon can be found at even higher elevations, such as the upper Hood River Valley at 2,000 feet above sea level.
It is now believed 1 in 3 homes in the Portland/Vancouver Metro area have elevated radon levels.
The Oregon Radon Program and Portland State University have collaborated to map radon potential by zip code; however, to use this resource alone to decide whether or not to test could be misleading.