Natural radioactivity from the building materials used in Islamabad and Rawalpindi, Pakistan

Studies have been carried out to determine the natural radioactivity in the building materials used for construction of dwellings in Islamabad and Rawalpindi, Pakistan. Measurements have been carried out on samples of bricks, cement, gravel aggregates, sand, soil and paints using a HPGe based gamma-ray spectrometer. In all the materials 40K, 226Ra and 232Th have been found; in paints activity was below the detectable limits. The overall activity (sum of activities) from 40K, 226Ra and 232Th in brick and soil samples was the highest and the lowest was found in gravel aggregate samples. The average activity of 40K varies from 51.3±3.8 Bq kg-1 (gravel aggregates) to 631.2±6.5 Bq kg-1 (bricks); 226Ra varied from 21.5±0.5 Bq kg-1 (sand) to 43.2±0.6 Bq kg-1 (bricks); 232Th varied from 9.9±0.6 Bq kg-1 (gravel aggregates) to 56.2±1.7 Bq kg-1 (soil). Radium equivalent activities with external and internal hazard indices have also been determined. The maximum value for the radium equivalent activity, 206.35 Bq kg-1, was found in soil, but it is less than the permitted value of 370 Bq Kg-1. All the materials have values for both external and internal hazard indices of <1. (author). 10 refs., 3 tabs