FRIDAY, April 4, 2008 (HealthDay News) -- You can't see, smell or taste radon.
The gas emanates naturally from the soil, seeping up into homes that rest on the ground. The only way to avoid it, really, is to have a house on stilts.
But the radioactive gas is the leading cause of lung cancer among nonsmokers in America, as well as the second leading cause of lung cancer overall, according to the U.S. Environmental Protection Agency. It claims about 21,000 lives annually.
"It is a health risk you can't see," said Kristy Miller, spokeswoman for the EPA's Office of Radiation and Indoor Air. "You can't touch it, you can't feel it. It is an inert gas. It's in your home for a long time, leaving no trail of evidence. It's only your proactive interest and testing that's going to prevent this health risk."
Radon is a global problem -- the World Health Organization says radon causes up to 15 percent of lung cancers worldwide.
About one of every 15 homes in the United States is estimated to have a dangerous radon level, which the EPA defines as more than 4 picocuries per liter of air.
Radon is produced from the natural decay of uranium, an element found in nearly all soils. "The earth is always emitting radon at some level," Miller said. "It's always a part of the outdoor ambient air, in trace amounts."
The gas typically moves up through the ground to the air above and into your home through cracks and other holes in the foundation. The home then traps radon inside.
"A home over the soil can act as a holding tank, allowing radon to accumulate to high levels," Miller said.
When inhaled, radon can damage the lungs by continuing to emit tiny bursts of alpha radiation, she said.
"The alpha emitters can actually damage the DNA of the lung tissue," Miller said. "The lung is extremely sensitive, compared with the skin."
Any amount of radon exposure is bad, the EPA says, but the cancer risk increases over time, as exposure is prolonged.
Because a house's radon level depends on many variables -- the composition of the soil, the construction of the house -- experts warn that any house might have high levels of the gas.
"Even if you have a new home, you might have high radon," said Bruce Snead, an extension specialist at Kansas State University specializing in radiation and indoor air quality. "The only way to know is to test."
The EPA recommends that any homeowner should conduct a radon test. The tests are easy to obtain. They're sold at hardware stores, and some local health departments and extension services offer to sell them at cost to homeowners, Snead said.
"People can test a home on their own," he said. "All they have to do is purchase a test kit, and read and follow the instructions."
The U.S. Surgeon General has recommended that people test their homes for radon every two years, and retest any time they move, make structural changes to the home or occupy a previously unused level of a house.
Homeowners also can hire a radon expert to come in and test levels, an action that some states require as part of a home sale, Snead said. About 20 states have laws requiring notification of radon levels in real estate transactions, and more are considering it, he said.
"Just as lead is a required notification, should the same thing happen with radon?" Snead said.
If high levels of radon are discovered, a relatively low-cost home repair can alleviate the problem, Snead said. The EPA recommends hiring a qualified radon mitigation contractor to do the work, because lowering high radon levels requires specific technical knowledge and special skills.
The most common method of radon reduction is called soil suction. It prevents radon from entering your home by drawing the radon from below the house and venting it through a pipe, or pipes, to the air above the house where it is quickly diluted, Snead said.
"The pipe discharges above the roof line, so this well-known carcinogen will dissipate into the atmosphere," he said. The pipes can work either passively, or with a fan used to pull air from the soil.
The average cost of a radon reduction system is about $1,200, according to the EPA. The cost generally ranges from $800 to $2,500, depending on the characteristics of the house and choice of radon-reduction methods.
Some homes now are being built to be radon-resistant, with gas-resistant foundations and sub-slab fill materials that allow gases to move easily away, Snead said.
Snead recommends that everyone, homeowner or renter, be proactive in dealing with the radon that could be building up in their homes.
"We save lives by having tests done and performing mitigation, and by building houses that are radon-resistant," he said.
To learn more, visit the U.S. Environmental Protection Agency.