Portland, Oregon – A dangerous gas could already be building inside homes across western Oregon as cool, damp spring nights keep windows closed, allowing radon—known as the “invisible killer”—to accumulate indoors within hours. The risk increases quickly when airflow is limited during overnight temperature drops and persistent moisture.
According to the U.S. Environmental Protection Agency, radon is a radioactive gas that forms naturally in soil and can enter homes through foundation cracks, basements, crawl spaces, and utility openings. While parts of Oregon are considered lower risk than other states, elevated levels have still been detected across the Portland metro area, the Willamette Valley, and eastern portions of the state, with some homes exceeding the EPA action level of 4 picocuries per liter.
In Portland and surrounding communities including Beaverton, Gresham, and Hillsboro, homes with basements and crawl spaces are especially vulnerable during early spring. Residents often keep homes sealed overnight to manage cooler air and rain, which can trap radon indoors. The Oregon Health Authority reports radon is the second leading cause of lung cancer in the United States, linked to about 21,000 deaths annually.
Radon exposure produces no immediate symptoms, making testing critical. Short-term test kits can return results within 48 to 96 hours, and mitigation systems can reduce indoor levels by up to 99 percent when properly installed.
Residents are urged to test homes now as conditions through April continue to support indoor buildup. Additional advisories may be issued as risks persist into early summer across the region.
