Studies find Iowa has the highest average radon concentrations in the U.S. and homeowners are urged to have their houses tested for the dangerous gas. Doug Clark, an environmental health specialist in Omaha/Council Bluffs, says there’s nothing Iowans can do to prevent radon from getting into their homes, as it’s a natural process.

Clark says, "The breakdown or decay of elements in the soil such as uranium and radium (creates the) gas that’s odorless and colorless." He says there are no indications radon is in your house as it does not cause headaches, nausea, sneezing or other symptoms.

Clark says the only way Iowans can find out if they have a radon problem is to get radon testing kits. "Set them up in one of the lower levels of your house and what they do is absorb any radon in the air and then you send them in for analysis."

Clark says the Midwest has exceptionally elevated radon levels. A recent study found nearly 60% of Iowa homes test above the "action level" set by the E.P.A.

"The central part of the nation, including Nebraska and Iowa are some of the areas where you find some of the highest levels of radon." Clark says radon is a killer and is the second-leading cause of lung cancer in the United States, behind only smoking.

Radon test kits can be purchased for $10 to $20 at most hardware and home center stores. January is Radon Action Month.