MEASUREMENT OF RADON EXHALATION RATE, RADIUM ACTIVITY AND ANNUAL EFFECTIVE DOSE FROM BRICKS AND CEMENT SAMPLES COLLECTED FROM DERA ISMAIL KHAN

Radon concentration, exhalation rate, radium activity and annual effective dose have been measured from baked and unbaked bricks and cement samples commonly used as construction material in the dwellings of Dera Ismail Khan City, Pakistan. CR-39 based NRPB radon dosimeters and RAD7 have been used as passive and active devises. The values of radon concentration for baked, unbaked bricks and cements obtained from passive and active techniques were found in good agreement. Average values of radon exhalation rates in baked, unbaked bricks and cement were found (1.202±0.212) Bq m^-2 h^-1, (1.419±0.230) Bq m^-2 h^-1 and (0.386±0.117) Bq m^-2 h^-1 and their corresponding average radium activity and annual effective dose were found (0.956±0.169) Bq/kg, (1.13±0.184) Bq/kg, (0.323±0.098) Bq/kg and (33.96±5.99) µSv y^-1, (40.3±6.51) µSv y^-1 and (10.94±3.28) µSv y^-1, respectively. Radon concentration, exhalation rate and their corresponding radium activity and annual effective dose were found higher in unbaked bricks as compared to baked bricks and cement but overall values of radon exhalation rate, annual effective dose and radium activity were found well below the world average values of 57.600 Bq m^-2 h^-1, 1100 µSv y^-1 and 370 Bq/kg, respectively.