Semi-experimental evaluation for radon exhalation rate and excess lifetime cancer risk from potential radon exposure for using fly ash building materials

In this work, the radon exhalation, annual effective dose and excess lifetime cancer risks due to the exposure of radon released from raw building materials containing fly ash of different fractions were evaluated. The 226 Ra and 222 Rn concentrations were evaluated by the measurements on HPGe gamma spectrometer, RAD 7 radon detector combined with model calculation of radon exhalation for standard rooms. The results indicated that the emanation fraction for fly ash is lower than the corresponding value for soils and rocks. The surveyed building materials of containing fly ash can result in an indoor radon concentration up to 1.7 Bq m −3 which is below the recommended value of 100 Bq m −3 by WHO, the annual effective dose increases from 0.007 to 0.022 mSv year −1 , the excess lifetime cancer risks ranges from 0.027 × 10 –3 to 0.085 × 10 –3 with the ratio of 3.2 for the additional fly ash content in cement up to 75%. In the meanwhile, it has a down trend and influences inconsiderably on these parameters for sand. The obtained mean annual effective doses are lower than the dose limitation of 10 mSv year −1 recommended for occupational workers.