Radon FAQ

Radon

Radon is a radioactive gas that forms naturally when uranium, thorium, or radium, which are
radioactive metals break down in rocks, soil and groundwater. People can be exposed to radon
primarily from breathing radon in air that comes through cracks and gaps in buildings and
homes. Because radon comes naturally from the earth, people are always exposed to it.

See also:

• Radiation Protection Division: Radon - https://www.epa.gov/radiation/radionuclide-basicsradon
• EPA's Integrated Risk Information System profile on Radon 222 [CASRN 14859-67-7] is located
at: https://cfpub.epa.gov/ncea/iris/iris_documents/documents/subst/0275_summary.pdf
• Radioactive Decay

Radon-222 is the decay product of radium-226. Radon-222 and its parent, radium-226, are part
of the long decay chain for uranium-238. Since uranium is essentially ubiquitous (being or
seeming to be everywhere at the same time) in the earth's crust, radium-226 and radon-222 are
present in almost all rock and all soil and water.


The amount of radon in the soil depends on soil chemistry, which varies from one house to the
next. Radon levels in the soil range from a few hundred to several thousands of pCi/L (picocuries
per liter) in air. The amount of radon that escapes from the soil to enter the house depends on the
weather, soil porosity, soil moisture, and the suction within the house.

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. In a small number of homes, the building materials can give off radon, too. However, building materials rarely cause radon problems by themselves.

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.


Read more about Radon health risks at www.epa.gov/radon/health-risk-radon

January is National Radon Action Month The aim of National Radon Action Month is to increase the public's awareness of radon, promote radon testing and mitigation, and advance the use of radon-resistant new construction practices.Radon Action Week is the third week in October. Some communities might observe Radon Action Week with other indoor air quality topics during the remaining weeks in October.

Radon in air is ubiquitous (existing or being everywhere at the same time). Radon is found in outdoor air and in the indoor air of buildings of all kinds. EPA recommends homes be fixed if the radon level is 4 pCi/L (picocurries per liter) or more. Because there is no known safe level of exposure to radon, EPA also recommends that Americans consider fixing their home for radon levels between 2 pCi/L and 4 pCi/L.


The average indoor radon concentration for America’s homes is about 1.3 pCi/L. It is upon this national average indoor level that EPA based its estimate of 21,000 radon-related lung cancers a year. The average concentration of radon in outdoor air is .4 pCi/L or 1/10th of EPA's 4 pCi/L action level.


Read "A Citizen's Guide to Radon" at www.epa.gov/radon/citizens-guide-radon-guide-protecting-yourself-and-your-family-radon


Read about Radon Health Risks at www.epa.gov/radon/health-risk-radon


Find out how to fix your home by reading a "Consumer's Guide to Radon Reduction: How to Fix Your Home" at www.epa.gov/radon/consumers-guide-radon-reduction-how-fix-your-home

Radon in air is ubiquitous (existing or being everywhere at the same time). Radon is found in outdoor air and in the indoor air of buildings of all kinds. EPA recommends homes be fixed if the radon level is 4 pCi/L (picocurries per liter) or more. Because there is no known safe level of exposure to radon, EPA also recommends that Americans consider fixing their home for radon levels between 2 pCi/L and 4 pCi/L.


The average indoor radon concentration for America’s homes is about 1.3 pCi/L. It is upon this national average indoor level that EPA based its estimate of 21,000 radon-related lung cancers a year. The average concentration of radon in outdoor air is .4 pCi/L or 1/10th of EPA's 4 pCi/L action level.


Read "A Citizen's Guide to Radon" at www.epa.gov/radon/citizens-guide-radon-guide-protecting-yourself-and-your-family-radon


Read about Radon Health Risks at www.epa.gov/radon/health-risk-radon


Find out how to fix your home by reading a "Consumer's Guide to Radon Reduction: How to Fix Your Home" at www.epa.gov/radon/consumers-guide-radon-reduction-how-fix-your-home

Radon and Health

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/health-risk-radon#beir). This report reinforces that radon is the second-leading cause of lung cancer and is a serious public health problem. As in the case of cigarette smoking, it would probably take many years and rigorous scientific research to produce the composite data needed to make an even more definitive conclusion.

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 (picocuries per liter of air), i.e., the lung cancer risk in miners has been documented at exposure levels comparable to those which occur in homes/residences.

There are no immediate symptoms from exposures to radon. Based on an updated Assessment of Risk for Radon in Homes, 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.

Radon Testing

EPA has maintained the position that radon measurement systems provide practical and affordable measurements that can give consumers the information they need about the radon level in their home in order to make a decision about whether to fix their home. Since EPA based this position on studies conducted earlier, we decided, in consultation with Office of Inspector General (OIG), to check the current state of device measurement accuracy.


This is a link to a contractor report that reviews current radon measurement proficiency data and compares it to earlier data -- www.epa.gov/radon/publications-about-radon. The report also provides a response to the OIG report regarding oversight of radon testing device accuracy and reliability (Rpt. No. 09-P-0151).


Results presented in this report support EPA’s position that radon testing devices provide accurate and reliable results and that EPA’s measurement recommendations raise the probability that high homes will be identified and fixed. While any measurement system has an associated variability in precision and accuracy, we expect that radon test devices that are used properly will provide accurate and reliable results.


The study presented here only represents a part of the picture of accuracy and reliability. Other efforts must be employed to contribute to this knowledge base; such as, blind studies carried out in the field, participation in the development of technical standards through private-sector,
consensus-based processes, support of state program technical needs and assessments of test chamber error.

Our general guidance (A Citizen's Guide to Radon - https://www.epa.gov/radon/citizens-guide-radon-guide-protecting-yourself-and-your-family-radon - suggests:


If your living patterns change and you begin occupying a lower level of your home (such as a basement) you should retest your home on that level.


Even if your test result is below 4 pCi/L, you may want to test again sometime in the future.


If you are buying or selling a home (from our Home Buyer's and Seller's Guide to Radon - https://www.epa.gov/radon/home-buyers-and-sellers-guide-radon):


If you are thinking of selling your home and you have already tested your home for radon, review the Radon Testing Checklist to make sure that the test was done correctly. If so, provide your test results to the buyer.


No matter what kind of test you took, a potential buyer may ask for a new test especially if:


• The Radon Testing Checklist items were not met;
• The last test is not recent, e.g., within two years;
• You have renovated or altered your home since you tested; or
• The buyer plans to live in a lower level of the house than was tested, such as a basement suitable for occupancy but not currently lived in.


A buyer may also ask for a new test if your state or local government requires disclosure of radon information to buyers.

Radon Mitigation

You have tested your home for radon, but now what? If you;have tested your home for radon and confirmed that you have elevated radon levels, 4 picocuries per liter in air (pCi/L) or higher, our guidance can help you:


• Select a qualified radon mitigation contractor to reduce the radon levels in your home.
• Determine an appropriate radon reduction method.
• Maintain your radon reduction system.


Radon reduction systems work. Some radon reduction systems can reduce radon levels in your home by up to 99 percent. 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. Get an estimate from a qualified radon mitigation contractors. Hundreds of thousands of people have reduced radon levels in their homes.

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.


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.

Radon gas is approximately 7.5 times heavier than air. It is however a noble gas with no chemical affinity but is easily influenced by air movements and pressure. In a house with forced air heating and cooling, radon gas can easily be distributed throughout the entire dwelling. When radon gas is discharged via a radon mitigation system above the roof, the radon concentration falls off dramatically


with distance from the point of discharge. In fact, the radon gas concentration approaches background levels at 3-4 feet from the discharge point. EPA disallowed ground level discharge of radon primarily because of the potential for re-entrainment of the gas into the house and because of the possibility of children being exposed to high radon levels. The
concentration of radon gas at the discharge point can be tens of thousands of picocuries per minute.

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