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Important Information on Radon Home Testing

EPA recommends that all homes should be tested and that any home with a measured radon level indoors of 4 picocuries per liter of air (pCi/L), or more, be mitigated to reduce radon levels. Radon is an odorless, colorless radioactive gas found in soil and water, and produced by the decay of uranium found naturally in soil. You should know that the average indoor radon level in the United States is 1.3 pCi/L, while the average outdoor (ambient) radon level is .4 pCi/L (one-tenth of the 4.0 pCi/L EPA action level). EPA's estimate of 14,000 radon related lung cancer deaths annually is based on exposure at 1.3 pCi/L over a long term. For a map of radon potential assessment based on geologic provinces, see EPA's Map of Radon Zones web page. Also check out Pennsylvania Radon Test Results Data Exit EPA Click for disclaimer and the West Virginia Map of Potential Radon Test Results. Exit EPA Click for disclaimer (PDF, 1pp, 65k, about PDF)

In September 1988, the Office of the U.S. Surgeon General issued a Health Advisory urging all Americans to test their homes for radon, and to fix them when elevated levels were found. In October that same year, Congress said that the national long-term goal ... with respect to radon ... is that (indoor air) should be as free of radon as the ambient air outside ....

Ten years after the Surgeon General's warning, on February 19, 1998, the National Academy of Sciences (NAS), reported that 12% of lung cancer deaths are linked to radon. The NAS is an independent, non-governmental scientific organization. NAS' best estimate is that radon causes between 15,000 and 22,000 lung cancer deaths each year in the United States. Further, the NAS found that even very small exposures to radon can result in lung cancer.

Neither the NAS nor EPA knows yet at what level radon might be safe, or not cause lung cancer. So, lowering your indoor radon level as much as possible is a very good idea. The following three consumer radon publications should answer most of your questions:

A Citizen's Guide to Radon

(402-K92-001, September 1994)

Home Buyer's and Seller's Guide to Radon

(402-R-93-003, March 1993)

Consumer's Guide to Radon Reduction

(402-K92-003, August 1992)

You can obtain copies of these documents from EPA's Philadelphia office (1-800-352-1973). Single copies of these publications are also available from EPA's Indoor Air Quality Information Clearinghouse (1-800-438-4318, or can be requested by fax-back at 1-703-356-4020). These and many other documents about radon and indoor air quality, are also available from one of EPA's websites (www.epa.gov/iaq/radon/pubs.html or www.epa.gov/iaq). You can also obtain them from the National Center for Environmental Information (NCEPI) Exit EPA Click for disclaimer, by calling 1-800-490-9198.

There are also many State and Local Agencies where assistance may be provided. They include:

Washington DC- Department of Public Health




Delaware Health and Social Services Administration




Pennsylvania Department of Environmental Protection




Virginia Radiological Health Programs




West Virginia Radiological Health Program




Maryland has no state-wide radon program so if you are a Maryland resident and have questions you can contact the U.S. Environmental Protection Agency's (EPA) Philadelphia Regional office for assistance. Call 1-800-352-1973 toll free, or 215-566-2086 or 215-566-3255, to talk with someone about radon, radon testing, how to reduce your home's radon levels, and what to do in a real estate transaction. Montgomery County residents should contact the county's Department of Environmental Protection (DEP) Radon Program for assistance; call 301-217-2177 or fax them at 301-217-2254. Montgomery County website Exit EPA Click for disclaimerthat includes radon and other environmental information. Montgomery County residents can obtain radon documents from their Department of Environmental Protection.

In addition you can call one of several hot lines operated by private non-profit organizations working in partnership with EPA. The National Safety Council operates a toll-free radon hotline (1-800-SOS-RADON (767-7236)), from which you can order a do-it-yourself radon test kit, and obtain basic information about radon testing. If you fix your home when the level is 4 pCi/L or more, you very likely will be able to reduce indoor levels to 2 pCi/L or less. For questions about fixing a home, you can contact the Consumer Research Council's radon-fix-it line by calling 1-800-644-6999.

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