Table 1: Radiological characteristics of cosmogenic NORM NORM and cosmic radiation account for over 85% of an ‘average individual’s’ radiation exposure.

A 70 kg person has 4400 Bq of K-40 – and 3000 Bq of carbon-14.) Cosmogenic NORM is formed as a result of interactions between certain gases in the Earth’s atmosphere and cosmic rays, and is only relevant to this paper due to flying being a common mode of transport.

Since most cosmic radiation is deflected by the Earth’s magnetic field or absorbed by the atmosphere, very little reaches the Earth’s surface and cosmogenic radionuclides contribute more to dose at low altitudes than cosmic rays as such.

Terrestrial NORM consists of radioactive material that comes out of the Earth’s crust and mantle, and where human activity results in increased radiological exposure.

The materials may be original (such as uranium and thorium) or decay products thereof, forming part of characteristic decay chain series, or potassium-40.

All minerals and raw materials contain radionuclides of natural origin.

The most important for the purposes of radiation protection are the radionuclides in the U-238 and Th-232 decay series.Long-lived radioactive elements such as uranium, thorium and potassium and any of their decay products, such as radium and radon are examples of NORM.These elements have always been present in the Earth's crust and atmosphere, and are concentrated in some places, such as uranium orebodies which may be mined.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.At higher altitudes, the dose due to both increases, meaning that mountain dwellers and frequent flyers are exposed to higher doses than others.