Indoor radon measurements in residential dwellings in Qom, Iran

Background: Inhalation of radon and its short-lived decay products is one of the most significant sources of exposure to natural radiation. Radon is the second cause of lung cancer in the populations. The present study was carried out under the projects of national radon, with the aim of determining the concentration of indoor in the city of Qom located in the central semi-arid region of Iran. Materials and Methods: Radon measurements were carried out in 123 dwellings using passive sampling with CR-39 detectors for 90 days. The map of radon concentration distribution was prepared using Arc GIS software and the statistical analysis was performed with SPSS version 20. Results: Indoor radon concentrations in Qom dwellings ranged from 15–259 Bq m^-3 . The arithmetic mean of indoor radon concentrations on basement, ground floors, first floors and second and upper floors were ,87.94 ,123.43 63.72and 40.69 Bq m^-3, respectively. Conclusion: A correlation was found between the distances from fault zones and measured indoor radon concentration. In most of cases, radon values were lower in well- ventilated dwellings in comparison with poorly-ventilated ones. Moreover, high radon concentration levels were observed in basements. The results indicated that in 30 places (24.3% of cases), the radon concentrations were higher than the reference levels recommended by the World Health Organization (100 Bq m^-3).