Radon is found throughout the United States, and is particularly prevalent in Colorado. The U.S. EPA has ranked Colorado as a Zone 1 area, which means that the average house will probably exceed the EPA's action level for indoor radon. Testing for radon is easy and inexpensive. Radon is produced as a decay product from uranium and radium. This naturally occurring radioactive gas is found in most soil and rock, and in most ground water.
All buildings contain some radon as does outdoor air, although at very low levels.
Since radon is a gas and is an inert element, it can easily travel through cracks and pores, without being chemically bound or attached to other elements. Voids and porous materials are found under every building, allowing easy entry for radon. The radioactive decay process begins with uranium. Uranium decays through several intermediate elements to produce radium and radon. Radon has a half-life of 3.8 days, which means half of the element will decay into RDPs in that time.