Material giving rise to these enhanced exposures has become known as naturally occurring radioactive material (NORM).
NORM is the acronym for Naturally Occurring Radioactive Material, which potentially includes all radioactive elements found in the environment.
Exposure to naturally occurring radiation is responsible for the majority of an average person’s yearly radiation dose (see also Nuclear Radiation and Health Effects paper) and is therefore not usually considered of any special health or safety significance.
However certain industries handle significant quantities of NORM, which usually ends up in their waste streams, or in the case of uranium mining, the tailings dam.
Concentrations of actual radionuclides may or may not have been increased; if they have, the term Technologically-Enhanced (TENORM) may be used.
The list of isotopes that contribute to natural radiation can be divided into those materials which come from the ground (terrestrial sources – the vast majority) and those which are produced as a result of the interaction of atmospheric gases with cosmic rays (cosmogenic).
NORM levels are typically expressed in one of two ways: Becquerels per kilogram (or gram) indicates level of radioactivity generally or due to a particular isotope, while parts per million (ppm) indicates the concentration of a specific radioisotope in the material.
Excluding uranium mining and all associated fuel cycle activities, industries known to have NORM issues include: Another NORM issue relates to radon exposure in homes, particularly those built on granitic ground.
Occupational health issues include the exposure of flight crew to higher levels of cosmic radiation, the exposure of tour guides to radon in caves, exposure of miners to radon underground, and exposure of workers in the oil & gas and mineral sands industries to elevated radiation levels in the materials they handle.