Annex 3
Radiation in perspective

Background radiation occurs naturally and comes from cosmic rays, rocks, soil, food and water. Ionising radiation (so-called because it produces an electrical effect called ionization when it strikes matter) can be easily detected with an instrument such as a Geiger tube and can be either natural or man-made.
It is produced by machines such as X-ray devices and radioactive materials.

In the UK, for example, over 85% of the ionising radiation received by the public comes from background radiation. The remaining 15% comes from artificial sources such as medical X-rays, and only around 0,1% comes from the nuclear power industry.

In France, the figure is quite similar:

Radioactive activity is measured in becquerels (Bq), or terabecquerels (TBq), where a TBq is a million, million becquerels. It measures the number of disintegrations of radioactive nuclei occurring each second in a sample. For instance, about 9,000 atoms disintegrate every second in the body of a person weighing 70 kg. Its activity is therefore 9,000 Bq.

The biological effects of radiation on the organism exposed is measured in sieverts (Sv). This is a health physics unit, expressed in equivalent dose which takes into account the characteristics of the radiation and of the organ irradiated. The millisievert (mSv), or a thousandth of a sievert, is very often used. Throughout the world, the annual average equivalent dose due to natural exposure is around 2.4 mSv.

The radiation doses received by individuals throughout the word will depend largely on local factors such as the type of rocks and soil or the height they live above sea level. Background radiation varies significantly from place to place and the average figures for various locations are as follows:

Type of occupation can also influence the radiation dose received by individuals. Typical figures for various occupations are as follows:

The International Commission on Radiological Protection (ICRP) keeps the subject of radiation protection under review and issues advice at appropriate times. ICRP advice is taken into account in formulating Euratom Directives on radiation protection which are embodied in UK and French legislation and is also embodied in Japanese regulations.