DOSES TO THE PORTUGUESE POPULATION DUE TO NATURAL GAMMA-RADIATION

The survey of natural gamma radiation in Portugal was initiated by a programme of outdoor measurements in regions of different geological identity. The present paper reports the completion of the programme with more detailed information and including additional regions such as the islands of Acores. Indoor measurements in some specific Districts namely Braganca, Viseu, Guarda, Lisboa and Setubal are also reported, these regions having been selected according to a criterion based on the outdoor radiation levels. In that way, Viseu and Guarda were expected to present high indoor gamma levels, while Setubal was surveyed since the low outdoor contribution pointed to lower indoor gamma ray levels. Outdoor and indoor terrestrial gamma dose rates and annual effective doses to the Portuguese population are presented in this work.