Radon is a radioactive noble gas, recognized as a carcinogenic agent, being affected by degree of ventilation. The aim of this preliminary study was to determine the concentration of indoor radon gas in schools, to estimate the main factors affecting their radon concentration levels and to analyze the effective dose received by students in Duhok schools. Therefore, the concentrations of radon were measured in 28 classrooms, from 13 schools located in Duhok city, using both RAD7 and Corentium monitor, from January 15-30, 2021. In all schools indoor radon was measured in four different scenarios of closed, natural and mechanical ventilation then, radon reduction rate between each case was calculated. In addition to that, exposure to annual effective dose of radon, for each different degree of ventilation, was evaluated. Furthermore, effects of building floors were studied. Results showed that maximum radon concentration, 121 Bqm(-3), was recorded in closed ventilation, while minimum, 15 Bqm(-3), was recorded in mechanical ventilation. Radon reduction rate in a mechanical ventilation is relatively large 81%. Also, results demonstrate that indoor radon levels at first floor, in all schools under study, were considerably greater than those at second and third floor (p < 0.05). The annual effective dose of all studied schools at 4 different cases of ventilation were found less than the worldwide average radiation dose of 3-10 mSv. So, it is not required to take any action to minimize the level of radon in schools under study.
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