These radon decay products, called “daughters,” attach themselves to dust particles floating in the air. When inhaled they can become lodged in the lung tissue. As these radon daughters decay, emitting the tiny bursts of energy, they can damage that lung cell tissue. Prolonged exposure can cause lung cancer. Scientific research indicates that at least a 10 to 20 year incubation period is required before a lung cancer develops. Scientists estimate that indoor radon is the number one cause of lung cancer in non-smokers and the number two cause of lung cancer (after smoking) in the United States. Up to 21,000 Americans may die each year as a result of radon exposure. The EPA considers radon to be the most significant environmental health risk we face today.