Radioactivity in building materials used in and around Dhaka city.

The activity levels of (226)Ra, (232)Th and (40)K were determined using gamma-ray spectroscopy in different commercial brands of cement, sand and hollow concrete bricks, which were collected from the building material suppliers of Dhaka City. The activity concentrations in the samples were found to be somewhat higher than in other countries. An effort has been made to assess the radiation hazard associated with these materials by determining the gamma activity concentration index I. It was found that the value of I for all the samples was <or=2, which indicates that the gamma dose contribution was not more than 0.3 mSv y(-1). The samples considered were safe for use in the construction of urban dwellings in Bangladesh and do not pose any significant source of radiation hazard.