Radon is a toxic, radioactive gas with no color, odor or taste that forms from the normal decay process of uranium, which is present in most rocks and soil. Uranium slowly breaks down to other products, including radium, which then breaks down to radon. This decay process produces alpha, beta, and gamma radiation.
Some of the radon moves to the soil surface and enters the outdoor air or enters a house or building through cracks in the foundation, while some radon remains below the soil surface and enters the groundwater. Radon levels in the soil range from a few hundred to several thousand pico Curies per liter (pCi/L). The amount of radon that escapes from the soil to enter the house depends on the weather, soil porosity, soil moisture, foundation integrity, and the suction within the house.
The EPA recommends a level of less than 4 pico Curies per liter (pCi/L) of radon in indoor air; however, there is no established safe level of radon. The EPA recommends remediation (taking action to lower the level) immediately if the radon level is greater than 4 pCi/L. Furthermore, EPA suggests that homeowners consider fixing radon levels between 2 pCi/L and 4 pCi/L to maintain a radon level of below 2 pCi/L. The average radon level in homes in the United States is 1.3 pCi/L, but certain parts of the country have higher average radon levels than others.
Pennsylvania has one of the most serious radon problems in the country. An estimated 40 percent of Pennsylvania homes have radon levels above Environmental Protection Agency’s action guideline of 4 picocuries per liter.