Abstract
It is a well known fact that natural radionuclides are the major contributors towards the gamma ray exposure received by the general public. In this context, soil samples were collected from the Islamabad capital territory and activities due to Ra-226, Th-232, K-40 and Cs-137 were measured using gamma ray spectrometry: activities ranged from 41.5-106.2 Bq kg(-1), 4.0-193.8 Bq kg(-1), 325.3-657.4 Bq kg(-1) and 1.6-9.45 Bq kg(-1), respectively. From the measured activities, the external hazard index, internal hazard index, absorbed dose rate and mean annual effective dose were calculated. External and internal hazard indices were calculated as 0.76 and 0.95, respectively. The mean absorbed dose rate was found to be 130.97 nGy h(-1). The mean effective dose was estimated as 0.16 mSv y(-1), which is less than the maximum permissible dose of 1 mSv y(-1).