More Radon Info

Radon is a radioactive gas that has been found in homes all over the United States. It comes from the natural breakdown of uranium in soil, rock and water and gets into the air you breathe. Radon typically moves up through the ground to the air above and into your home through cracks and other holes in the foundation. Radon from soil gas is the main cause of radon problems. Radon can also enter your home through well water. In a small number of homes, the building materials can give off radon, too. However, building materials rarely cause radon problems by themselves. Your home can trap radon inside. Any home can have a radon problem. This means new and old homes, well-sealed and drafty homes, and homes with or without basements. Local geology, construction materials, and how the home was built are among the factors that can affect radon levels in homes. In fact, you and your family are most likely to get your greatest radiation exposure at home. That is where you spend most of your time. Nearly 1 out of every 15 homes in the United States is estimated to have an elevated radon level (4 pCi/L or more). High radon levels have been found in every state.

Based on a national residential radon survey completed in 1991, the average indoor radon level is about 1.3 picocuries per liter (pCi/L) in air in the United States. The average outdoor level is about 0.4 pCi/L. Radon problems do vary from area to area, but the only way to know your radon level is to test. A neighbor’s test result is not a good indication of whether your home has a problem. Radon levels can vary greatly from home to home. There are simple solutions to radon problems in homes. Short-term tests can be used to decide whether to reduce a home’s high radon levels. However, the closer the short-term testing result is to 4 pCi/L, the less certainty there is about whether the home’s year-round average is above or below that level. Keep in mind that radon levels below 4 pCi/L still pose some risk and that radon levels can be reduced to 2 pCi/L or below in most homes.

Radon Health Affects:

There are no immediate symptoms from exposures to radon. Based on an updated Assessment of Risk for Radon in Homes (see www.epa.gov/radon/risk_assessment.html), radon in indoor air is estimated to cause about 21,000 lung cancer deaths each year in the United States. Smokers are at higher risk of developing Radon-induced lung cancer. Lung cancer is the only health effect which has been definitively linked with radon exposure. Lung cancer would usually occur years (5-25) after exposure. There is no evidence that other respiratory diseases, such as asthma, are caused by radon exposure and there is no evidence that children are at any greater risk of radon induced lung cancer than adults. The World Health Organization (WHO), the National Academy of Sciences, the US Department of Health and Human Services, as well as EPA, have classified radon as a known human carcinogen, because of the wealth of biological and epidemiological evidence and data showing the connection between exposure to radon and lung cancer in humans.

There have been many studies conducted by many different organizations in many nations around the world to examine the relationship of radon exposure and human lung cancer. The largest and most recent of these was an international study, led by the National Cancer Institute (NCI), which examined the data on 68,000 underground miners who were exposed to a wide range of radon levels. The studies of miners are very useful because the subjects are humans, not rats, as in many cancer research studies. These miners are dying of lung cancer at 5 times the rate expected for the general population. Over many years scientists around the world have conducted exhaustive research to verify the cause-effect relationship between radon exposure and the observed increased lung cancer deaths in these miners and to eliminate other possible causes.

Radon Test Results:

The average indoor radon level is estimated to be about 1.3 pCi/L; roughly 0.4 pCi/L of radon is normally found in the outside air. The U.S. Congress has set a long-term goal that indoor radon levels be no more than outdoor levels. While this goal is not yet technologically achievable for all homes, radon levels in many homes can be reduced to 2 pCi/L or below. A radon level below 4 pCi/L still poses a risk. Consider fixing when the radon level is between 2 and 4 pCi/L. As with other environmental pollutants, there is some uncertainty about the magnitude of radon health risks. However, we know more about radon risks than risks from most other cancer-causing substances. This is because estimates of radon risks are based on data from human studies (underground miners). Additional studies on more typical populations are under way. Your radon measurement will give you an idea of your risk of getting lung cancer from radon. Your chances of getting lung cancer from radon depend mostly on: your home’s radon level; the amount of time you spend in your home; and whether you are a smoker or have ever smoked.

Radon Remediation:

EPA recommends that you take action to reduce your home’s indoor radon levels if your radon test result is 4 pCi/L or higher. It is better to correct a radon problem before placing your home on the market because then you have more time to address a radon problem. If elevated levels are found during the real estate transaction, the buyer and seller should discuss the timing and costs of the radon reduction. The cost of making repairs to reduce radon levels depends on how your home was built and other factors. Most homes can be fixed for about the same cost as other common home repairs. Your costs may vary depending on the size and design of your home and which radon reduction methods are needed. Check with and get an estimate from one or more qualified mitigators. Radon reduction systems work. Some radon reduction systems can reduce radon levels in your home by up to 99 percent.

A variety of methods can be used to reduce radon in homes. Sealing cracks and other openings in the foundation is a basic part of most approaches to radon reduction. EPA does not recommend the use of sealing alone to limit radon entry. Sealing alone has not been shown to lower radon levels significantly or consistently. In most cases, a system with a vent pipe(s) and fan(s) is used to reduce radon. These “subslab depressurization” systems do not require major changes to your home. Similar systems can also be installed in homes with crawl space. These systems prevent radon gas from entering the home from below the concrete floor and from outside the foundation. Radon mitigation contractors may use other methods that may also work in your home. The right system depends on the design of your home and other factors.

Select a qualified radon-reduction contractor to reduce the radon levels in your home. Any mitigation measures taken or system installed in your home must conform to your state’s regulations. In states without regulations covering mitigation, EPA recommends that the system conform to American Society for Testing and Materials International, or ASTM standard E2121. EPA recommends that the mitigation contractor review the radon measurement results before beginning and radon-reduction work. Test again after the radon mitigation work has been completed to confirm that previous elevated levels have been reduced. Choose a radon mitigation contractor to fix your radon problem just as you would for any other home repair. You may want to get more than one estimate, ask for and check their references. Make sure the person you hire is qualified to install a mitigation system. Some states regulate or certify radon mitigation services providers.