Indoor radon concentration levels in several districts of the Punjab Province-Pakistan

Exposure to natural sources of radiation, especially 222Rn and its short-lived daughter products has become an important issue throughout the world because sustained exposure of humans to indoor radon may cause lung cancer. Therefore, indoor radon concentration levels have been measured in several districts of the Punjab Province. These included Gujranwala, Gujrat, Sialkot, Mandibahauddin, Hafizabad and Narowal districts. Twenty to 30 houses were carefully selected in each district. CR-39-based NRPB radon dosimeters were installed in living rooms and bedrooms of these houses and were exposed to radon for a period of three months (i.e. from September to December 2005). Radon concentration levels were found to vary from ∼40±5 to 173±4 and 38±5 to 193±4 (Bqm-3) in the living rooms and bedrooms, respectively. Annual effective doses were calculated. Using ICRP-65 conversion values, annual effective doses were found to range from 0.60±0.08 to 3.27±0.08mSv. It ranged from 0.87±0.12 to 4.75±0.12mSv when UNSEAR 2000 dose conversion values were used. Radon concentration levels and annual effective doses were found to be within recommended limits.