April 6, 1998
Volume 50, No. 27
Radon is everywhere but too much exposure can endanger your health
Radon gas can cause lung cancer. In fact, the Surgeon General, the Environmental Protection Agency and public health organizations say radon is the second leading cause of lung cancer behind smoking. Radon is a naturally occurring gas present just about everywhere. That's the bad news; the good news is that it is easy to detect, and that makes it easier to limit our exposure.
Radon is an odorless, colorless "daughter product" of uranium. As uranium undergoes radioactive decay, radioactive radon and other elements are produced. Uranium is present in all rocks. If you look around long enough, you may actually find small spots of yellow uranium on Stone Mountain.
Radioactivity from radon is harmful when it enters the lungs. The radioactive (alpha) particles released when radon decays cannot penetrate human skin.
Humans have been breathing radon since the beginning of history, and our bodies have learned to absorb certain amounts of it. But studies of miners who worked around high concentrations of radon have shown its harmfulness. These studies were used to determine safe concentration levels of the gas and to produce risk estimates of cancer for different concentrations.
The unit of concentration of radon gas is pCi/L, or "picoCuries per liter." This indicates how much radon will decay in one liter of air. The EPA advises radon levels should stay below 4 pCi/L. The average level of homes tested throughout the United States is about 1.2 pCi/L, but estimates indicate about 6 percent of all homes have a concentration greater than 4 pCi/L.
If 1,000 nonsmokers were to breathe in air at 4 pCi/L over a lifetime, only two would develop lung cancer. If all smoked, about 30 would develop cancer. Although either may cause lung cancer, smoking and radon exposure have a synergistic relationship.
How do we know how much radon we are breathing? Radon gas arises from the ground and travels easier through dry soils, seeping into homes through small cracks and pores in the foundation. The amount of radon-forming uranium in the soil varies immensely. Because radon gas is heavier than air, it settles in basements and lower levels. The materials from which your house is made and the quality of your water can also affect the amount of radon present in a home. Your house may have an unusually high level of radon, while your next door neighbor has a very low one. Therefore, the only way to truly determine the concentration of radon is to have your home tested.
You can do this by buying an inexpensive, easy-to-use radon testing kit or hire a local contractor. Both should be EPA listed or state certified. Some health departments test homes for free.
Should you happen to have a high concentration of radon, there are mitigation techniques available. Improving the foundation sealing and using a technique called "sub-slab depressurization" together will significantly lower indoor radon levels. The local EPA can recommend a contractor, and an estimate is relatively inexpensive.
Because there is conclusive evidence of radon's potential to induce lung cancer, we must all be aware of its presence. Since April is Cancer Control Month, it is a good time to test the radon level in your home. You can find out more by calling the Pollution Prevention Assistance Division in the Georgia Department of Natural Resources at 1-800-745-0037.
Steve Grimm is a senior health physicist for the Radiation Safety Office, a division of Emory's Environmental Health and Safety Office. "Wellness" is coordinated by the Center for Health Promotion and the Rollins School of Public Health.