Three main categories of exposures can be distinguished (ICRP, 2007a):

1. Occupational exposures, which are all exposures incurred by workers in the course of their work, with the exception of

— excluded exposures and exposures from exempt activities involving radiation or exempt sources

— any medical exposures

— the normal local natural background radiation.

2. Public exposures, which are exposures incurred by members of the public from radiation sources, excluding any occupational or medical exposure and the normal local natural background radiation.

3. Medical exposures of patients.

Exposures of comforters and carers, and exposures of volunteers in research, are treated separately in radiation protection. From the above categories, the only ones relevant for NPPs are occupational and public exposures.

It is to be noted that while the categorization of exposure does not rec­ognize gender distinctions, if a female worker at the NPP has declared that she is pregnant or nursing, additional controls have to be considered in order to attain a level of protection for the embryo/fetus broadly similar to that provided for members of the public.