An-Najah Staff

Indoor radon has been recognized as one of the health hazards for mankind because long-term exposure to radon increases the risk of developing lung cancer. This study aims at assessing the contribution of building materials towards the total indoor radon exposure to the inhabitants of Nablus district. Radon exhalation rate have been carried out for common building materials used in construction in Nablus district from both national and international origins. The closed-can technique has been employed in this study using solid state nuclear track detectors (CR-39). After 100 days of exposure to radon, CR-39 detectors were etched chemically by (6.25 N) NaOH solution at 75oC for 5 hours and then counted under an optical microscope. The measured track densities were related to radon exhalation rate, radon concentration, the effective radium content, and the annual effective dose for forty seven building material samples. Results obtained from the current study show that radon exhalation rates from granite and marble have relatively high values as compared to other building material samples followed- in order- by cement, ceramic, concrete, building stones, and porcelain, while gypsum, sand, gravel and bricks contribute less to radon exhalation rate. The average radon exhalation rate in the studied samples ranged from (55.37 ± 15.01) mBq/m2h for gypsum samples to (589.54 ± 73.24) mBq/m2h for granite samples, with a total average value of (268.56 ± 166.21) mBq/m2h, the corresponding total average value of radon concentration and effective radium content are (148.49 ± 91.13) Bq/m3 and (1.93 ± 1.20) Bq/Kg, respectively. On the basis of these values the annual effective dose for each sample was also determined and compared with the effective dose limit values recommended by the National Council on Radiation Protection and Measurements (from 1 to 5 mSv/y). In general, the annual effective doses from the investigated building materials are low and under the global value except for granite, marble and some cement samples with average values (8.12 ± 1.02), (6.06 ± 1.25), and (5.16 ± 0.84) mSv/y, respectively. Thus the studied materials are safe as construction materials especially with good ventilation rate, but special care must be taken when using granite, marble, and cement as building materials.