Radon is an odorless, tasteless, colorless radioactive noble gas that naturally occurs as a result of the breakdown of uranium in soil and rock. Uranium decays into radium and then into radon. Uranium and radium as solids are trapped in the soil, but radon gas is able to move through the soil. When the air pressure in a house or building is lower than that of the soil beneath the structure, radon gas will enter through structural openings and cracks, and migrate through the slab. When radon gas decays, it produces radioactive decay products. The decay products are heavy metals polonium, bismuth, and lead. When they decay, wave length and particle radiation are produced. Radon is also found in building materials such as concrete and concrete block. The standard for corrective action established by the USEPA is 4 pico Curries per liter (pCi/L), and can only be detected by specialized tests.
