Radon is an odorless, radioactive gas formed by the breakdown of uranium found in soil, rocks beneath and around building foundations, ground water wells, and some building materials.
Though it does not elicit immediate symptoms, exposure to radon in homes can increase the risk of lung cancer. The U.S. Environmental Protection Agency (EPA) estimates that radon is the number one cause of lung cancer in non-smokers, responsible for as many as 21,000 cancer deaths each year. The combination of smoking and the presence of radon in the home can significantly increase the risk of lung cancer.
According to EPA, nearly one out of every 15 homes in the U.S. has elevated radon levels. Radon may be present in any home or building, regardless of age. Because radon is a gas, it can leak into homes through the basement or crawl space, cracks in concrete floors and walls, floor drains and sump holes, or through well water. Any home may have a radon problem—new or old, well-sealed or drafty, with or without a basement.
Radon from soil is the main source of exposure. Health risks from radon in drinking water are much lower and are only a significant concern in certain parts of the country. The largest risk from radon-contaminated water comes from the gas being released into the air when water is used for showering and other household purposes.
Radon levels vary nationally. EPA publishes maps of the country and each state, assigning each county to one of three zones based on the expected average radon level in a typical home. While designed to guide building construction standards, the maps are helpful in understanding the regional differences in radon levels. However, any home in any zone can contain elevated radon levels.
Testing for Radon
Because radon is invisible, odorless, and tasteless, testing is the only way to know if a home has a high concentration of radon. EPA and the Surgeon General recommend that all residences below the third floor of a building be tested for radon. Both schools and homes should be tested. In apartment buildings, it is most important to test units on the basement level where radon from the ground is likely to be highest, though tests should also be conducted on the first and second floors of any apartment complex.
Anyone can conduct a radon test. There are both short-term and long-term radon tests. EPA recommends initial measurements for radon be taken with short-term tests placed in the lowest lived-in level of the residence. Radon testing kits are available at a discounted price from the National Safety Council’s Radon Hotline (1-800-767-7236) and at various retail locations such as hardware stores. Almost all states recommend that the homeowner or tenant conduct the test himself or herself or hire a contractor who is certified by the National Environmental Health Association or the National Radon Safety Board. A list of certified testers can be obtained by contacting the radon office in the relevant state, the National Environmental Health Association’s Radon Proficiency Program, or the National Radon Safety Board.
Once a radon test has been obtained, the enclosed directions are usually easy to follow and the procedure is simple and straightforward. Typically, the process will consist of setting out a small canister or packet containing activated carbon in the lowest occupied portion of the home and then, two days later, collecting the container, placing it in a foil bag, and mailing it to a lab. The lab should be able to report the results within one week. Find out more from the Alliance's radon background information and testing materials.
EPA has established a recommended action guideline of four picocuries of radon per liter (pCi/L) of air in residences. (A picocurie is a measure of radioactivity.) EPA recommends that action be taken to reduce radon levels when this guideline is exceeded. The presence of radon over the EPA standard is not a violation of local housing codes in most cities. The long-term goal is to reduce indoor radon levels to average outdoor levels of 0.4 picocuries per liter. Because of technology limits, EPA’s short-term goal is to achieve home radon concentrations below two picocuries per liter.
If test results exceed the EPA recommended action guideline of four pCi/L, a second follow-up measurement should be taken and depending on the results, EPA standards may recommend radon mitigation.
If actions to mitigate radon are going to be taken in the home, there are many options within two broad categories of action:
1. Prevent the radon from entering the home.
2. Reduce the level of radon after it has entered.
For all options, EPA recommends that a contractor be retained to do the work and estimates that this will cost from $500 to $2500 per home, depending on the characteristics of the structure and choice of radon reduction methods. Common methods may involve the installation of underground pipes, venting fans, plastic sheeting, and/or sealants over floor and wall cracks.