Indoor exposure assessment of radon in the elementary schools, Palestine

Many public health agencies rank residential radon exposure as the second leading cause of lung cancer after cigarette smoking. It has been shown that the risk coefficient for lung cancer is higher for children than that for adults. Therefore, indoor radon measurements were carried out in the elementary schools of Tulkarem province, West Bank, Palestine. Two hundred and thirty solid state nuclear track detectors (SSNTDs) type CR-39 were distributed in the classrooms of 20 elementary schools in Tulkarem province area. About thirty of them were used for quality assurance purposes. The CR-39 detectors were exposed in the schools for three months during the school summer holiday from May 2012 to August 2012 and then collected and etched in Sodium Hydroxide (NaOH) 6.25 N solution at 75 °C for 6 h. The tracks were counted manually at the digital microscope. The indoor radon levels were generally low, ranging from 3.48 to 210.51 Bq/m3 (Becquerel per cubic meter), with a mean radon concentration (mean±SE; standard error) of 40.42± 2.49 Bq/m3. The average annual radon effective dose was assessed to be (mean±SE) 0.17 ± 0.01 mSv/y (milliSievert per year) while the excess lifetime lung cancer risk was approximately 0.09%. The results obtained indicate that the indoor radon concentration was significantly affected by the floor level of the classroom (negatively correlated) and the school building age (positively correlated). The radon concentration and the resulting dose in the schools were within the reference levels of the International Commission on Radiological Protection (ICRP). Better ventilation is recommended to decrease the risk to the minimum.