Assessment of radiological hazards due to the presence of natural radionuclides in samples of building materials collected from the northwestern areas of Pakistan.

Brick, sand, marble and cement are mainly used for the construction of dwellings in Pakistan. Therefore, knowledge of the presence of natural radioactivity in these materials is of great importance in order to assess the radiological hazards associated with them. In this context, specific activities of 226Ra, 232Th and 40K were measured in brick, sand, marble and cement samples collected from different localities of the North West Frontier province and federally administered tribal areas, Pakistan, using a P-type coaxial high-purity germanium spectrometer. In brick samples, the average measured activities for 226Ra, 232Th and 40K were 30 +/- 15, 41 +/- 21 and 523 +/- 182 Bq kg(-1), whereas in sand samples, these values were 19 +/- 9, 30 +/- 15 and 769 +/- 461 Bq kg(-1), respectively. In marble samples, the average specific activities of 226Ra, 232Th and 40K were found to be 18 +/- 19, 18 +/- 21 and 299 +/- 328 Bq kg(-1), whilst in cement samples they were 24 +/- 6, 18 +/- 4 and 244 +/- 29 Bq kg(-1), respectively. Radium equivalent activities were also calculated and were found to be 129 +/- 54, 121 +/- 57, 67 +/- 60 and 68 +/- 9 Bq kg(-1) for brick, sand, marble and cement samples, respectively. The annual average effective doses from these samples were 0.37 +/- 0.15, 0.33 +/- 0.15, 0.20 +/- 0.17 and 0.20 +/- 0.03 mSv, respectively. External and internal hazard indices were less than one for all the samples studied.