The severe drought baking some parts of the United States—particularly California and the Pacific Northwest—may be increasing the risk of radon gas inside homes.
As water tables drop in some areas, lower depths that can contain uranium and radon are exposed, according to experts. As the uranium ore decays over time, it produces radon, a radioactive gas that has been linked to lung cancer.
"What happens in drought conditions is the aquifers are getting lower and lower and exposing more bedrock and more uranium," said James Connell of A1 Radon in Olathe, Kansas. "Cracks in the ground and cracks in people's foundations allow those radon gases to come up."
Jeanne Case, who lives just outside Portland, Oregon, recently tested for radon at her home and it showed levels three times the safe limit. "It never even occurred to me ... I was so convinced we didn't have it," Case told NBC Portland affiliate KGW-TV.
Radon problems are more associated with wet, winter months, but cancer-causing radon levels can accumulate in homes in the warm weather when people have their air conditioners running full force.
"Opening windows and ventilating dramatically reduces any radon that might get in," said Jonathan Modie, a spokesman for the Oregon Public Health Division.
Modie said some people also could be exposed to higher radon levels if they "sleep in the basement when it is hot, where radon levels are typically higher." Radon is heavier than air, so concentrations in basements tend to be twice as high as on first floors.
Washington state—particularly the northeastern portion of it—has historically shown higher levels of radon gas than Oregon, according to data from the U.S. Environmental Protection Agency. California's radon levels are highest along the state's Central Coast, including Santa Barbara County,
"People are getting more aware of radon," said Fred Ellrott of Radon Be Gone in Somis, California.
Wet weather is usually more common for elevated radon levels, since wet ground allows the gases to move more quickly to the surface. Also, people tend to close windows indoors for longer periods when it's raining outside, allowing the tasteless, odorless and invisible radon gas in the house.
Well water also can contain radon and contribute to the levels of the gas in indoor air.
A1 Radon's Connell, who tests for radon in the Kansas City area, said, "Considerably higher levels of radon" occurred in portions of the Midwest region during drought years, particularly 2010, 2011 and 2012. The "past two years haven't had a drought per say and radon levels have come down here," he said.
The EPA estimates that radon causes more than 20,000 lung cancer deaths in the U.S. annually. Fixing the radon problem usually involves putting in a ventilation system to remove the gases from underneath a home's foundation and venting them into the air to keep the radon gases from seeping into the home.
"It's not a real expensive problem to fix," said Connell. Radon tests average about $100, he said, and the cost to repair homes runs on average approximately $800.