Decisions to take action in order to: :
1° Prevent or reduce the risk of exposure in a radiological emergency;
2° Protect people from a risk resulting from radioactive contamination of the environment or of products originating from contaminated areas or manufactured from contaminated materials;
3° To prevent or reduce a risk arising from exposure to a natural source of ionising radiation.
A radiological emergency is any situation involving a source of ionising radiation that requires a rapid response to mitigate serious negative consequences for health, the environment or property, or a risk that could lead to such serious negative consequences.
The principle of optimisation is applied to these decisions as a matter of priority when the exposure of the population is greater than the reference levels defined by regulation, and continues to be applied below these levels.
It applies in the same way to the implementation of actions taken by persons involved in the situations defined in 1° and 3°.
The exposure to natural sources of ionising radiation mentioned in 3° excludes exposure resulting from the presence of natural radionuclides in the human body, cosmic radiation at ground level and radiation from radionuclides, other than radon, present in the earth’s undisturbed crust.