FAQs
How does radon get into your home?
What are the health effects from exposure to radon?
What is the debate on radon?
Are we sure that radon is a health risk?
How do I know if my radon mitigation system is working properly?
How do we know radon is a carcinogen?
Should I test the soil for radon before building?
How does radon get into your home?
Any home may have a radon problem.
Radon is a radioactive gas. It comes from the natural decay of uranium that is found in nearly all soils. It typically moves up through the ground to the air above and into your home through cracks and other holes in the foundation. Your home traps radon inside, where it can build up. Any home may have a radon problem. This means new and old homes, well-sealed and drafty homes, and homes with or without basements.
Radon from soil gas is the main cause of radon problems. Sometimes radon enters the home through well water (see "Radon in Water" below). In a small number of homes, the building materials can give off radon, too. However, building materials rarely cause radon problems by themselves.
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What are the health effects from exposure to radon?
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
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What is the debate on radon?
There is no debate about radon being a lung carcinogen in humans. All major national and international organizations that have examined the health risks of radon agree that it is a lung carcinogen. The scientific community continues to conduct research to refine our understanding of the precise number of deaths attributable to radon. The National Academy of Sciences BEIR VI Report (see www.epa.gov/radon/beirvi.html ) has estimated that radon causes about 15,000 to 22,000 lung cancer deaths annually based on their two-preferred models. Major scientific organizations continue to believe that approximately 12% of lung cancers annually in the United States are attributable to radon.
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Are we sure that radon is a health risk?
EPA already has a wealth of scientific data on the relationship between radon exposure and the development of lung cancer. The scientific experts agree that the occupational miner data is a very solid base from which to estimate risk of lung cancer deaths annually. While residential radon epidemiology studies will improve what we know about radon, they will not supersede the occupational data. Health authorities like the Centers for Disease Control (CDC), the Surgeon General , the American Lung Association, the American Medical Association, and others agree that we know enough now to recommend radon testing and to encourage public action when levels are above 4 pCi/L. The most comprehensive of these efforts has been the National Academy of Science's Biological Effects of Ionizing Radiation (BEIR VI) Report (see www.epa.gov/radon/beirvi.html). This report reinforces that radon is the second-leading cause of lung cancer and is a serious public health problem.
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How do I know if my radon mitigation system is working properly?
There are several methods that a contractor can use to lower radon levels in your home. Some techniques prevent radon from entering your home while others reduce radon levels after it has entered. EPA generally recommends methods which prevent the entry of radon. Soil suction, for example, prevents radon from entering your home by drawing the radon from below the house and venting it through a pipe, or pipes, to the air above the house where it is quickly diluted. We offer some tips on what to look for to check the contractor's work here. Checking Your Contractors Work Similar to a furnace or chimney, radon reduction systems need some occasional maintenance. You should look at your warning device on a regular basis to make sure the system is working correctly. Fans may last for five years or more (manufacturer warranties tend not to exceed five years) and may then need to be repaired or replaced. Replacing a fan will cost around $200 - $350 including parts and labor. It is a good idea to retest your home at least every two years to be sure radon levels remain low.
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How do we know radon is a carcinogen?
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.
In addition, there is an overlap between radon exposures received by miners who got lung cancer and the exposures people would receive over their lifetime in a home at EPA's action level of 4 pCi/L (pico Curries per Liter), i.e., the lung cancer risk in miners has been documented at exposure levels comparable to those which occur in homes/residences.
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Should I test the soil for radon before building?
This answer is covered in our publication, Building Radon Out - on page 22.
Soil testing for radon is not recommended for determining whether a house should be built radon-resistant. Although soil testing can be done, it cannot rule out the possibility that radon could be a problem in the house you build on a lot. Even if soil testing reveals low levels of radon gas in the soil, the amount of radon that may enter the finished house cannot be accurately predicted because one cannot predict the impact that the site preparation will have on introducing new radon pathways or the extent to which a vacuum will be produced by the house. Furthermore, the cost of a single soil test for radon ranges from $70 to $150, and at least 4 to 8 tests could be required to accurately characterize the radon in the soil at a single building site. Therefore, the cost to perform the soil testing is very high when compared with installing the passive radon system in high radon potential areas (see the EPA Map of Radon Zones ).
Why not wait to install the radon-resistant features until after the home is completed and a radon test is peformed?
It is much easier and far less costly to prepare the sub-grade to improve the soil gas flow before the slab is cast. Also, the pipe for the radon-resistant system itself can be run more easily through the house before it is finished. This significantly improves aesthetics and can reduce subsequent system operating costs by planning to route the pipe through warm space to maximize passive operation of the system. The best way to determine the radon level in a home: Test the home for radon after occupancy.
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