Like all physicians, we learned about radon, an odorless gas that has been linked to lung cancer. However, it wasn't until one of us tried to purchase a house--and the inspection revealed elevated radon levels--that the issue struck home.
Radon gas is produced by the decay of uranium, an element almost universally present in soil and rock. Radon moves slowly through ground soil and can enter homes through openings or cracks in the foundations and construction joints. Over time, levels of radon gas in homes can build up.
The relationship between radon and lung cancer was first recognized in the 1950s, when it was observed that uranium miners exposed to very high levels of radon were dying of lung cancer at rates far greater than expected. Initially, how radon caused cancer was unknown. We now understand that radon gas is breathed into the lungs, where it begins to decay, releasing high-energy, radioactive particles (called alpha particles) that can damage lung tissue and cause lung cancer.
Today, most scientists believe that even relatively low-level exposure to radon increases lung cancer risk. The Environmental Protection Agency has established 4 picocuries of radon per liter of air as the "action level" for radon reduction. The EPA estimates that if 1,000 people were exposed to this level of radon over a lifetime, between 13 and 50 would die of lung cancer as a result.
Radon levels vary from location to location, depending primarily on the amount of uranium in the soil. Los Angeles County, for example, is not considered to have particularly high levels of radon, with approximately 1% or fewer homes believed to have levels above the EPA's action level. (Riverside and San Bernardino counties are estimated to have levels, on average, comparable to those of Los Angeles County, while Orange County rates are believed to be lower than 1%.) Ventura County, on the other hand, is considered a high radon area; in one survey, more than 14% of the homes in certain parts of the county had elevated levels.
The EPA, however, recommends radon testing even in areas with relatively low levels, such as Los Angeles. Testing is done by placing a small radon-sensitive device on the wall of your home. After a period ranging from several days to several months, the detector must be sent to a laboratory, where a reading is calculated.
Two types of tests are available. Short-term tests expose the detector for fewer than 90 days, while long-term tests can extend to one year. Because radon levels vary with the season, short-term measurements can sometimes be misleading. Short-term tests performed in the summer, for example, may underestimate your exposure; those taken in the winter can overestimate it. Although results are not quickly available with long-term tests, they do provide a better estimate of your year-round exposure.
The EPA recommends that you begin with a short-term test. If the result of that test is 4 picocuries of radon per liter or higher, the measurement should be repeated for confirmation.
A state-certified expert can test your home or you can buy a do-it-yourself test kit, available at hardware stores for about $10. Be sure to buy a home test kit that meets EPA requirements, and follow the instructions that come with it.
Select a frequently used room on the lowest lived-in level of the house (for example, if you converted the basement into a bedroom or playroom, the test should be done there). Place the detector on a wall at least 20 inches above the floor and well away from windows and doors. Leave the detector undisturbed for the appropriate amount of time, then send it promptly to the laboratory.
If you find that the radon level in your home is 4 picocuries of radon per liter or higher, take steps to lower it. Sometimes, reducing radon levels is as simple as sealing foundation cracks or improving ventilation; in other cases, more extensive work may be necessary. To find out more about radon reduction and to obtain a list of radon-mitigation companies in your area, contact the Consumer Federation of America Foundation's Radon Fix-it Program at (800) 644-6999. The program is free.
For more information on radon, visit the Environmental Protection Agency's Web site at http://www.epa.gov/iaq/radon, or contact the National Safety Council's radon hotline at (800) SOS-RADON.
* Dr. Jonathan Fielding is the director of public health and the health officer for the Los Angeles County Department of Health Services. Dr. Valerie Ulene is a board-certified specialist in preventive medicine practicing in Los Angeles. They can be reached by e-mail at email@example.com.
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