University of Wisconsin - Extension

If you are buying or selling a home you may be asked about radon. It is an environmental health question that home buyers may have about the houses they are considering. Radon is a radioactive gas produced naturally from the decay of uranium and radium. Radon is odorless and colorless, so you cannot see or smell it. Since small amounts of uranium and radium are common in many Wisconsin soils, radon is also common in Wisconsin. While radon is more common in some areas of the state than others, radon levels high enough to cause concern have been found in homes in all Wisconsin counties.

Radon is measured in picoCuries per liter (pCi/L) of air. A PicoCurie represents the decay of about two radon gas atoms per minute in about a quart of air. The U.S. Environmental Protection Agency (EPA) recommends that action be taken to lower radon levels of four pCi/l or higher.

Radon does not cause direct respiratory problems, headaches or other immediate health problems. However, prolonged exposure increases the chances of lung cancer. The EPA has determined that an average lifetime exposure of four pCi/L gives nonsmokers two chances in a thousand of dying from lung cancer. The higher the life time exposure the greater the risk of lung cancer is. The risk to tobacco smokers from radon exposure is dramatically greater.

Data collected by the Wisconsin Department of Health and Family Services (DHFS), indicates that between five and ten per cent of the homes in Wisconsin have average radon levels of four pCi/L or higher on the main floor. You can find information on radon measurements for your zip code by visiting the web site, "Radon Information for Wisconsin" at http://www.dhfs.state.wi.us/dph_beh/RadonProt/ . Only the measurements reported to DHFS are included. You will notice that there are at least a few measurements above four pCi/L in most zip codes that have significant numbers of measurements in the database. However, radon levels within a neighborhood vary widely so the only way to know if a particular house has high levels of radon is to test.

Fortunately, testing can be done with kits available from local hardware stores, home centers, public health departments or radon information offices. The cost is usually less than $20. The kit usually contains a canister that you open and place in the lowest lived-in level of your house for about two days when the house is closed up and the heating system is running. Under these conditions radon levels will be at their highest. The lowest lived-in level is usually the main level unless you spend seven or more hours per week in the basement or ground level.

The kit will come with specific instructions for placement and exposure time. Once the canister has been exposed for the recommended time you seal it up and mail it to a lab for analysis. The cost of the analysis is included in the original cost. In a short time you will receive a report back with the results. Note that there are special recommendations for testing when done as part of a real estate transaction. For more information on testing and interpreting test results contact your local Radon Information Center. You can reach a Radon Information Center by calling 1-888 Low-Radon (1-888-569-7236).

Reducing radon levels is a challenge. Radon gas originates in soil and rocks. It diffuses, as does any gas, by flowing along the path of least resistance to the earth's surface and then to the atmosphere. Common entry paths for radon include earth floors, sump pump wells, floor drains, gaps in floors and around pipes, visible and microscopic cracks, holes left from form ties, construction joints and hollow concrete block walls.

In existing homes, sealing apparent openings usually does not reduce radon levels enough to solve a radon problem. It is usually necessary to provide a system to suck air from under the basement floor slab as well. This is known as sub slab ventilation. It involves drilling one or more holes through the concrete and fitting plastic pipes in these holes. The pipes are then extended to the roof. A fan may be installed to increase the effectiveness of the system. The cost to have a contractor do this work is usually around $1,200. Protecting new construction against radon is much less expensive. The web site and Local Radon Information Centers have lists of companies that have received training to do this work.

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