Exposure of urban populations to natural gamma background in Poland

Studies of indoor and outdoor terrestrial gamma ray background in the urban environment of six administrative provinces with enhanced gamma radiation in Poland (southern part of the country) were performed in order to assess annual effective gamma dose equivalent rates per capita of urban populations in the provinces. It was found that average gamma dose rates in air were between 42 and 123 nGy.h-1 indoors and between 34 and 145 nGy.h-1 outdoors. Indoor-to-outdoor ratios of provincial average weighted gamma dose rates were between 1.05 and 1.50. Assuming occupancy factors indoors and outdoors to be 0.8 and 0.2 respectively, average effective dose equivalent rates per capita were assessed to be between 0.27 and 0.72 mSv.a-1, whereas provincial average weighted values per capita ranged between 0.35 and 0.55 mSv.a-1. The results obtained have been compared with corresponding data for some other countries. (author)