Naturally Occurring Radioactive Materials - NORM

Naturally Occurring Radioactive Materials (NORM) consist of materials present in the environment, such as Uranium (mainly U-238), Thorium (mainly Th-232) and Potassium (K-40) and any of their decay products, such as radium (mainly Ra-226) and radon (mainly Rn-222). These natural radioactive elements are present in low concentrations in earth's crust and are brought to the surface through human activities such as oil and gas exploration or mining and through natural processes like leakage of radon gas to the atmosphere or through dissolution in ground water.