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Question: I am a new home owner. A friend suggested that I have my home tested for radon, but I don't know anything about it. Can you advise me on radon and on how to get my home tested?
Answer: Radon is naturally occurring, odorless, and colorless gas produced by the breakdown of uranium in soil, rock, and water. Because radon is a gas, it can enter buildings through openings or cracks in the foundation. The radon gas itself decays into radioactive solids, called radon daughters. The radon daughters attach to dust particles in the air, and can be inhaled. The inhalation of radon daughters has been linked to lung cancer.
You can get radon detection devices at many hardware and home improvement stores, or by contacting the EPA's National Radon Hotline (1-800-SOS-RADON). These devices are left in the home for 2 to 90 days, and indicate whether there might be a radon problem in the home. If results indicate that your home has a level exceeding 4 picocuries (pC/L), you will want to test your home again with the short, 2 to 90 day test and then calculate the average of the two tests, or test your home with an alpha track detector, which measures the long term radon average for three to twelve months. If the radon level in your home exceeds 4 pC/L, there are several techniques available to the lower levels.
Radon graphic(91 kb)
The decay of each radioactive element occurs at a very specific rate. How fast an element decays is measured in terms of the element "half-life", or the amount of time for one half of a given amount of the element to decay. Uranium has a half-life of 4.4 billion years, so a 4.4-billion-year-old rock has only half of the uranium with which it started. The half-life of radon is only 3.8 days. If a jar was filled with radon, in 3.8 days only half of the radon would be left. But the newly made daughter products of radon would also be in the jar, including polonium, bismuth, and lead. Polunium is also radioactive - it is this element, which is produced by radon in the air and in people's lungs, that can hurt lung tissue and cause lung cancer.
(74 kb) Radon levels in outdoor air, indoor air, soil air, and ground water can be very different.
Because the level of radioactivity is directly related to the number and type of radioactive atoms present, radon and all other radioactive atoms are measured in picocuries. For instance, a house having 4 picocuries of radon per liter of air (4 pCi/L) has about 8 or 9 atoms of radon decaying every minute in every liter of air inside the house. A 1,000-square-foot house with 4 pCi/L of radon has nearly 2 million radon atoms decaying in it every minute.
Radon levels in outdoor air, indoor air, soil air, and ground water can be very different. Outdoor air ranges from less than 0.1 pCi/L to about 30 pCi/L, but it probably averages about 0.2 pCi/L. Radon in indoor air ranges from less that 1 pCi/l to about 3,000 pCi/L, but it probably averages between 1 and 2 pCi/L. Radon in soil air (the air that occupies the pores in soil) ranges from 20 or 30 pCi/L to more than 100,000 pCi/L; most soils in the United States contain between 200 and 2,000 pCi of radon per liter of soil air. The amount of radon dissolved in ground water ranges from about 100 to nearly 3 million pCi/L.
Why do radon levels vary so much between indoor air, outdoor air, soil air, and ground water? Why do some houses have high levels of indoor radon while nearby houses do not? The reasons lie primarily in the geology of radon - the factors that govern the occurrence of uranium, the formation of radon, and the movement of radon, soil gas, and ground water.
State Geological Surveys are good sources of information (geologic maps and radioactivity surveys) on the geology of the states. For information on soils in your area, the first place to start is the county agricultural extension agent. Telephone numbers and addresses for these state and county government agencies are in the phone book.
All states have radon contact agencies, usually the state health departments or divisions of environmental or radiation protection. These agencies and the regional offices of the U.S. Environmental Protection Agency (EPA) are good sources of general information about the health risks of radon, radon measurements in your house, and corrections of radon problems. The publications listed under "Suggested Readings - General References" are among those available from EPA. Many state radon agencies have these or similar publications available. For technical information on the geology of radon, look at the publications listed under "Suggested Readings - Technical References".
(121 kb) U.S. Environmental Protection Agency Regions
EPA Region 1 JFK Federal Building Boston, MA 02203 EPA Region 2 26 Federal Plaza New York, NY 10278 EPA Region 3 841 Chestnut Street Philadelphia, PA 19107 EPA Region 4 345 Courtland St. N.E. Atlanta GA 30365 EPA Region 5 230 South Dearborn Street Chicago, IL 60604 EPA Region 6 1445 Ross Avenue Dallas TX 75202-2733 EPA Region 7 726 Minnesota Avenue Kansas City, KS 66101 EPA Region 8 One Denver Place, Suite 1300 999 18th Street Denver, CO 80202-2413 EPA Region 9 215 Fremont Street San Francisco, CA 94105 EPA Region 10 1200 Sixth Avenue Seattle, WA 98101
General References (these texts or similar materials are available from your regional EPA office)
U.S. Environmental Protection Agency,
Technical References (these articles or similar materials may be available in large regional reference libraries or from specific sources, as indicated. Of particular interest to the serious student are the periodicals Radon Protection Dosimetry, Journal of Geophysical Research, and Health Physics, which contain many technical articles on this subject.)
Nazaroff, W.W., and Nero, A.V., Jr., Eds., 1988, Radon and its decay products in indoor air: New York, John Wiley and Sons, Inc., 518 p.
Nielson, K.K., Rogers, V.C., and Gee, G.W., 1984, Diffusion of radon through soils: a pore distribution modes: Soil Science Society of America Journal, V. 48, no. 3, p. 482-487.
Otton, J.K., Schumann, R.R., Owen, D.E., Thurman, Nelson, and Duval, J.S., 1988, Map showing radon potential of rocks and soils in fairfax County, Virginia: U.S. Geological survey Miscellaneous Field Studies Map MF-2047, scale 1:62,500.
Sachs, H.M., Hernandez, T.L., and Ring, J.W., 1982, Regional geology and radon variability in buildings: Environment International, v. 8, no. 1-6, p. 97-103.