Variation of annual effective dose due to radon level in indoor air in Marwar region of Rajasthan, India

In the present work, indoor radon and thoron measurements have been carried out from different locations of Jodhpur and Nagaur districts of Northern Rajasthan, India using RAD7, a solid state alpha detector. The radon and thoron concentration in indoor air varies from 8.75 to 61.25 Bq m⁻³ and 32.7 to 147.2 Bq m⁻³ with the mean value of 32 and 73 Bq m⁻³ respectively. The observed indoor radon concentration values are well below the action level recommended by International Commission on Radiological Protection (200-300 Bq m⁻³) and Environmental Protection Agency (148 Bq m⁻³). The survey reveals that the thoron concentration values in the indoor air are well within the International Commission on Radiological Protection (2005). The calculated total annual effective dose due to radon level in indoor air varies from 0.22 to 1.54 mSv y⁻¹ with the mean value of 0.81 mSv y⁻¹ which is less than even the lower limit of action level 3-10 mSv y⁻¹ recommended by International Commission on Radiological Protection (2005)