Dangerous radon seeps in through the cracks

    Radon gas is the leading cause of lung cancer for non-smokers. That is one reason the Environmental Protection Agency (EPA) has declared that next week is ?National Radon Awareness Week.? The EPA estimates that radon claimed the lives of 20,000 Americans in 2009 via lung cancer. Of these, about 2,900 were people who had never smoked.

    Radon is a naturally occurring gas that is both colorless and odorless. It is produced by the breakdown of uranium in soil, rock and water. When radon decays into radioactive solids, it can attach to dust particles that find their way into unsuspecting lungs.

    The EPA rates counties? radon levels as high, moderate and low. Every county in Iowa is listed as high. Rick Welke, radon program manager at the Iowa Department of Public Health, explained that Iowa has the highest percentage of homes at risk of radon contamination in the country. He said the reason for that is found in Iowa?s geology.

    During the most recent ice age, which was at its peak 20,000 years ago, a glacier covered much of North America, including Iowa. When it receded, it left behind uranium deposits in the soil. Uranium decayed into radium, which in turn decayed into radon. The end result of those uranium deposits is that 200 to 400 Iowans contract lung cancer from radon exposure every year.

    Welke remarked that most soil in Iowa will test highly for radon levels, but that alone doesn?t indicate how much radon will enter a home. He said that depends on how easily gas can pass from the soil into the house. Radon can find its way into a home through crawl spaces and cracks in the foundation, and can even seep in through the concrete.

    Air moves from high pressure to low pressure zones, and Welke said that a basement is a low pressure zone, meaning air moves toward it. He said that second stories are under what he calls ?positive pressure? which means air moves away from them. He said that is why it is more important to test for radon in the lower parts of a building, where it is likely to be.

    ?Most commercial buildings are under positive pressure because of their air handling system, so that when you open their doors, air comes rushing out,? he said. ?We see more problems with radon in residential structures, which have parts of the building under negative pressure.?

For more, see our Oct. 12 print edition.