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 ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs 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.

Print publication: Issue 4 (December 2009)
Received 9 February 2009, in final form 23 April 2009, accepted for publication 7 July 2009
Published 18 November 2009