Indoor Exposure Assessment and Health Hazard of Radon in the Elementary Schools of Tulkarem Province, Palestine

Many public health agencies rank residential radon exposure as the second leading cause of lung cancer after cigarette smoking. Furthermore, it has been shown that the risk coefficient for lung cancer is higher for children than that for adults. Therefore, there is a special interest in radon measurement in kindergartens and elementary schools in different countries. This study aims to investigate the indoor radon levels in the elementary schools of Tulkarem province for the first time. As well as to set a baseline data for Tulkarem schools which would be of great help for “school’s radon survey in the West Bank” in the near future. This study also aims to investigate the different parameters that may influence the indoor radon concentrations by different radon measurements methods such as active and passive methods. Two hundred and thirty Solid-State Nuclear Track Detectors (SSNTDs) type CR-39 were distributed in the classrooms of twenty elementary schools located in Tulkarem province using stratified random sampling method of public, private and United Nations schools. About thirty of them were used for quality assurance purpose (10% duplicate detectors and 5% blank detectors). 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. In parallel, twenty active measurements performed by RAD7 monitor (Durridge Company) were carried out in the same twenty classrooms for quality assurance and correlation analysis between the two types of measurements (passive and active). The indoor radon levels results 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 research also focused on parameters affecting radon concentrations such as geographic location, the age of the building, school authority in relating to the building style and building material, and floor number of the classrooms. The study findings, as expected, showed that radon concentrations in ground floors were higher than in upper floors. The old-age school buildings showed significantly higher radon concentrations than new ones. The two measurements (CR-39 and RAD7) showed a highly significant correlation with (R2) = 0.97. Our results were below the action level provided by the United States Environmental Protection Agency of 148 Bq/m3 which indicates no radiological health hazard. However, the relatively high concentrations in some classrooms can be reduced by increasing the natural ventilation or classrooms supply with suction fans. The results obtained indicate that the indoor radon concentration was significantly affected by the floor level of the classroom and the school building age.