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Any home can 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 www.epa.gov/radon/rnwater.html). In a small number of homes, the building materials can give off radon, too. However, building materials rarely cause radon problems by themselves
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 & IEMA 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 & IEMA also recommend that homes with levels between 2 pCi/l and 4 pCi/L have their homes mitigated.
The average indoor radon concentration for homes in the United States 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 indoor air is .4 pCi/L or 1/10th of EPA’s 4 pCi/L action level.
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 at www.epa.gov/radon/pubs/consguid.html 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.
EPA & IEMA recommend retesting every 2 years. You also should consider retesting if you have renovated or altered your home since the last test.
It is possible for any granite sample to contain varying concentrations of uranium and other naturally occurring radioactive elements. These elements can emit radiation and produce radon gas, a source of alpha and beta particles and gamma rays. Some granite used for countertops may contribute variably to indoor radon levels. Some types of granite may emit gamma radiation above typical background levels. However, at this time EPA believes that the existing data is insufficient to conclude that the types of granite commonly used in countertops are significantly increasing indoor radon levels. While radiation levels are not typically high, measurement of specific samples may reveal higher than expected levels on a case-by-case basis. Granite is a naturally occurring igneous rock, meaning that it was formed by the cooling of molten rock. It is quarried and processed to produce commercial products such as countertops.
EPA believes the principal source of radon in homes is from the soil in contact with basement floors and walls. To reduce the radon risk you should first test the air in your home to determine the radon level. There are many do-it-yourself radon test kits available through retail outlets and on-line, starting at about $25. While natural rocks such as granite may emit radiation and radon gas, the levels attributable to such sources are not typically high.
If your home has a radon level of 4 picocuries per liter (pCi/L) of air or more, you should take steps to fix your home and reduce the radon level. Contact your state radon office (www.epa.gov/radon/whereyoulive.html) for assistance. Hire a qualified radon professional (www.epa.gov/radon/radontest.html) to fix or mitigate your home. The key to reducing your risk of lung cancer from radon is to test your home and mitigate when necessary. A specially-trained and qualified radiation professional may be equipped to test for other radon sources (such as granite or diffusion from drinking water) when diagnosing the nature and source of your home’s radon problem.
Radon is a gaseous radioactive element having the symbol Rn, the atomic number 86, an atomic weight of 222, a melting point of -71ºC, a boiling point of -62ºC, and (depending on the source, there are between 20 and 25 isotopes of radon – 20 cited in the chemical summary, 25 listed in the table of isotopes); it is an extremely toxic, colorless gas; it can be condensed to a transparent liquid and to an opaque, glowing solid; it is derived from the radioactive decay of radium and is used in cancer treatment, as a tracer in leak detection, and in radiography. (From the word radium, the substance from which it is derived.)
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.