Release of Radon from Soil to the Living Places

 S. A. Mujahid and S. Hussain

Environmental Radiation Laboratory
Physics Research Division, PINSTECH
P. O. Nilore, Islamabad, Pakistan

The indoor radiation mainly comes from radon. After inhalation its daughters stay in the lungs and become a permanent source of radiation and may cause lungs cancer. The indoor radon originates from soil and building materials with soil as the main source. Water is also a source of radon and it contributes to the indoor activity through taps and piping in the kitchen and bath rooms. The concentration of radon is usually higher in the less ventilated places. In the present work, the exhalation rate of radon from soil has been estimated.  A number of soil samples were collected from the city of Rawalpindi, sealed in the bottles and analyzed for radon by an active method based on the alpha scintillator. These data of concentration were used to calculate the radon exhalation rates by an analytical model. The calculated values of radon exhalation rates were found in the ranges 90 - 350 mBq m-2 h-1 respectively. A survey of indoor activity concentration due to radon was also conducted in the same city in order to check the variation of its concentration in the living places. It is found that none of the results exceed EPA action level limit of 148 Bq m-3.