Natural radioactivity in some building materials in Cuba and their contribution to the indoor gamma dose rate

The natural radioactivity of some building materials commonly used in Cuba was measured by gamma spectrometry. Typical concentrations encountered so far encountered are in the ranges: 47-2511 Bq kg - 1 for 4 0 K; 9-71 Bq kg - 1 for 2 2 6 Ra; and 2-38 Bq kg - 1 for 2 3 2 Th. The external gamma ray absorbed doses in indoor air and the corresponding effective dose-equivalents in a typical dwelling are presented in this paper.