en Radiation Biology Radiation Biology تحقيق بديع Original Research <span style="font-weight: bold">Background: </span>Health hazards associated with exposure due to the natural radioactivity which is a part of our physical environment are of great concern. In order to assess the risks associated with exposure due to the natural radioactivity in soil and building materials, extensive studies have been carried out all over the world. The most commonly encountered radionuclide’s are ²³⁸U, ²³²Th, their decay products and ⁴⁰K. <span style="font-weight: bold">Materials and Methods:</span> In order to study the concentration of these radionuclides soil, sand, gravel aggregates, bricks and marble, samples were collected from different sites and local suppliers of the district Mirpur, Azad Kashmir (Pakistan). ²²⁶Ra, ²³²Th, and ⁴⁰K activities in the collected samples were measured using HPGe detector. The measured specific radioactivity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in the studied samples ranged from 10 ±1 to 47 ± 2, 18 ± 1 to 75 ± 4 and 40 ± 3 to 683 ±3 Bq.kg-1, respectively. <span style="font-weight: bold">Results:</span> From the measured activity concentration, radium equivalent activity, external and internal hazard indices, gamma and alpha indices, terrestrial absorbed dose and annual effective dose were calculated. Maximum value of radium equivalent activity of 197.1 ± 9 Bq.kg-1 was observed in soil sample whereas minimum value of 45.9 ± 2 Bq.kg-1 was found in gravel aggregates. Relatively higher mean values of hazard indices were found in brick samples. Annual effective dose varied from 0.06 ± 0.01 to 0.47 ± 0.02 mSv.y-1. <span style="font-weight: bold">Conclusion:</span> Current values of annual effective dose, radium equivalent activity and hazard indices have been found to be within the recommended limits. Iran. J. Radiat. Res., 2011 9(2): 77-87 Building materials, radiological hazards, radium equivalent activity, annual effective dose, external and internal hazard indices 77 87 http://ijrr.com/browse.php?a_code=A-10-1-387&slc_lang=en&sid=1 M. Rafique mrafique@gmail.com 790031947532846002242 790031947532846002242 Yes H. Rehman 790031947532846002243 790031947532846002243 No Matiullah 790031947532846002244 790031947532846002244 No F. Malik 790031947532846002245 790031947532846002245 No M.U. Rajput 790031947532846002246 790031947532846002246 No S.U. Rahman 790031947532846002247 790031947532846002247 No M.H. Rathore 790031947532846002248 790031947532846002248 No