Building materials are one of the potential sources of indoor radioactivity because of the naturally occurring radionuclides in them. Radon exhalation rate is one of the most important factors for evaluation of the environmental radon level. Radon contributes more than half of the total ionizing radiation dose 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 destroyed building materials in war 2014 towards the total indoor radon exposure to the inhabitants of in . 40 Samples have been collected from common destroyed building materials in Jabalia district. The closed-can technique has been employed in this study using solid state nuclear track detectors (CR-39). After 124 days of exposure to radon, CR-39 detectors were etched chemically by (6 N) NaOH solution at 75°C for three months and then counted under an optical microscope. Results obtained from the current study show that radon exhalation rates from concrete and asbestos have relatively high values as compared to other building materials while glass, marble and a red brick contribute less to radon exhalation rate. The average radon exhalation rate in term of area in the studied samples ranged from (86.506) mBq.m^-2.h^-1 for glass samples to (469.017) mBq.m^-2.h^-1 for Concrete samples. In general, the annual effective doses from the investigated building materials are low and under the global value (from 1 to 5 mSv/y) except for Concrete and asbestos samples with average values (9.464) and (9.3528) mSv/y, respectively.

radon, CR39, calibration, building materials