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Realizing the risks of radon

Cross-section illustration of home showing interior rooms and exterior landscapeKandace Fisher-McLean, MS, HHS, Housing and Environmental Design Specialist, St. Louis County, University of Missouri Extension


Radon is a radioactive gas that you cannot smell, see or taste. According to the National Cancer Institute, minimal levels of radon typically exist in all air. However, when radon is concentrated at high levels within the air of your home it can increase your chance of developing lung cancer when you breathe it in. The National Cancer Institute, the Environmental Protection Agency (EPA) and the Surgeon General caution that radon exposure is the second leading source of lung cancer in the United States behind cigarette smoking. If you are a cigarette smoker and are exposed to radon gas, the risk of lung cancer is compounded. The EPA states that approximately 21,000 lung cancer fatalities each year in the U.S. are connected to radon exposure.


According to the EPA, radon gas is found everywhere in the United States and it is produced from the natural breakdown of uranium in soil, rock and water. Radon gas moves through the ground into the air and travels into your home through gaps, cracks and holes in the foundation. It can also enter through the water supply of your home. Once radon gas is in your home it can build up to dangerous levels. Approximately 1 out of every 15 homes in the United States has increased levels of radon.


January is National Radon Action Month and it's a good time to have your home tested. Radon is problematic any time of the year but the EPA explains that radon levels can escalate during colder months because people spend more time inside with their windows closed. Testing is the only method to detect the level of radon in your home. Fortunately, do-it-yourself test kits are fairly easy and inexpensive. If you do not want to do the test yourself or if you are buying or selling a home you may want to hire a qualified professional who is unbiased in the real estate process to conduct a radon test. Contact the Missouri Department of Health and Senior Services (MDHSS) for a list of qualified professional radon testers. The EPA suggests connecting with the privately organized national radon programs listed on their website for qualified radon professionals in your area.


Here are steps for testing your home for radon:


  1. Obtain a short-term radon test kit. The EPA recommends using a short-term radon test kit for the fastest way to test for radon in your home. Missouri residents can obtain one free radon test kit for their home through MDHSS. The application is easy to fill out and is available at You can also purchase a radon test kit at most hardware stores for around $10 to $20, which includes the cost of mailing and reading the results. If you purchase a kit, ensure that the kit meets the performance requirements of the US EPA radon gas measurement proficiency program, which should be stated on the box. The EPA explains that you should follow all package directions exactly as stated to make sure you are conducting the test properly and that you are placing the radon measurement device in the correct area. The package directions also tell you where to send the device once the test is completed in order to obtain your results.
  2. Conduct the radon test. The EPA suggests keeping your windows and outside doors closed as much as you can during the test. Do not disturb the radon measurement device during the test and place it on the lowest lived-in level of your house. If you utilize the basement regularly, test there. If not, test on the first floor of your home in a room that you normally use like a bedroom, den or playroom, but not in the kitchen or bathroom. For more specific details on how to use a basic short-term radon test kit, refer to the EPA publications listed in the resource section at the end of this article.
  3. Interpreting your test results. At the conclusion of the radon test, the EPA advises you to follow the kit instructions on how and where to send the test kit so that your results can be interpreted. Test results should be received in a few weeks. Radon is measured in picocuries per liter of air or pCi/L. If the result of your test reveals that you have a radon level of 4pCi/L or higher, either a long-term test or a second short-term test should be conducted to verify the results. To connect with a qualified radon professional in your area to assist with further testing, contact the MDHSS or contact the private national radon programs listed on the EPA website.


If levels continue to read 4pCi/L or greater after further testing, a radon mitigation system will need to be installed in your home by a qualified professional. Numerous methods exist for reducing radon levels in your home. One common method is to use a vent pipe system and fan, which pulls radon from under the foundation and vents it outside above the house. This system is known as a soil suction radon reduction system and does not require extreme alterations to your home. However, this is only one example for reducing radon and qualified contractors may use various treatment methods depending on the design of your home. In addition to installing the mitigation system, a contractor will recommend sealing any foundation cracks and openings in your home. The cost of reducing radon in your home can differ, but the good news is that, according to the EPA, radon levels can be reduced by up to 99 percent with some systems. The EPA recommends that a post mitigation test be performed within 30 days of the installation of your radon reduction system.


Methods also exist for constructing new homes with radon-resistant features to prevent radon from entering. For more information on such methods, go to the Radon Publications page on the EPA website.


To locate a professional in Missouri who specializes in radon testing and mitigation, contact:
Bureau of Environmental Epidemiology
Missouri Department of Health and Senior Services
P.O. Box 570, Jefferson City, MO 65102
Phone: 573-751-6102 or 866-628-9891
MO DHSS radon website:


References & Resources:

EPA: Radon home page
Missouri Department of Health and Senior Services: Radon
National Cancer Institute: Radon and Cancer
National Library of Medicine, Tox Town: Radon
Kansas State University: National Radon Program Services


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Last update: Tuesday, January 10, 2017