Radon decays quickly, giving off tiny radioactive particles. When inhaled, these radioactive particles can damage the cells that line the lung. Long-term exposure can lead to lung cancer, the only cancer proven to be associated with inhaling it.
Cigarette smoking is the most common cause of lung cancer. Radon represents a far smaller risk for this disease, but it is the second leading cause of lung cancer in the United States. Scientists estimate that approximately 15,000 to 22,000 lung cancer deaths per year are related to radon.
Although the association between radon exposure and smoking is not well understood, exposure to the combination of radon gas and cigarette smoke creates a greater risk for lung cancer than either factor alone. The majority of radon-related cancer deaths occur among smokers.
Testing is the only way to know if a person's home has elevated radon levels. Indoor levels are affected by the soil composition under and around the house, and the ease with which the gas enters the house. Homes that are next door to each other can have different indoor levels, making a neighbor's test result a poor predictor of risk. In addition, precipitation, barometric pressure, and other influences can cause radon levels to vary from month to month or day to day, which is why both short- and long-term tests are available.
Short-term detectors measure radon levels for 2 to 90 days, depending on the device. Long-term tests determine the average concentration for more than 90 days. Because levels can vary from day to day and month to month, a long-term test is a better indicator of average radon levels. Both tests are relatively inexpensive and easy to use. A state or local radon official can explain the differences between testing devices and recommend the most appropriate test for a person's needs and conditions.
The U.S. Environmental Protection Agency (EPA) recommends taking action to reduce radon in homes that have a level at or above 4 picocuries per liter (pCi/L). About 1 in 15 U.S. homes is estimated to have radon levels at or above this EPA action level. Scientists estimate that lung cancer deaths could be reduced by 2 to 4 percent, or about 5,000 deaths, by lowering radon levels in homes exceeding the EPA's action level.
The cost of a radon reduction depends on the size and design of a home, as well as the reduction methods that are needed. These costs typically range from $800 to $2,500, with an average cost of $1,200.