Radiological significance of building bricks in Pakistan

Baked clay bricks samples were collected from both urban and rural areas of the North West Frontier Province of Pakistan and natural radioactivity due to 40K, 226Ra and 232Th has been measured in these samples. The specific absorbed dose rates due to natural radioactivity emanating from the walls, floors and ceilings of the typical model rooms made of these building bricks have been calculated applying the mesh size adaptive volume integral methodology. The occupancy factor, representing the weighted average of all the population in the country, was taken to be 0.3 in this study. The values of estimated annual effective dose rates for whole body were found to be 0.38 and 0.35 mSv.y(-1) for the two types of model rooms. These values are smaller than those predicted by UNSCEAR for normal background areas. Thus the building bricks analysed in this study do not pose any significant health problem to the population.