NORMs distribution in the dust samples from the educational institutions of Megacity Dhaka, Bangladesh: Radiological risk assessment

Abstract

This study demonstrates the specific radioactivities of primordial radionuclides in dust samples collected from educational institutions of the megacity Dhaka, Bangladesh. Elemental levels from neutron activation analysis were converted into the corresponding radioactivity. Meann=26 radioactivity abundances of 226Ra, 232Th, and 40K (NORMs: Naturally Occurring Radioactive Materials) in the dust sample were 28.6, 43.8, and 462 Bq.kg−1, respectively, where 232Th and 40K activities were relatively higher compared to the corresponding world mean values (232Th: 30 Bq.kg−1, and 40K: 400 Bq.kg−1). Alterations in NORMs abundances compared to the source materials (surface soil) were explained in terms of weathering followed by aerodynamic transportation. Calculation of usual radiological indices invokes human health hazards. Considering the higher vulnerability of school going children and juveniles towards ionizing radiations and the entrance of NOMRs-containing dust particles into the respiratory system, the estimated radiological indices only demonstrate the possible lowest risks. But in a real scenario, alpha particles from the decay series of 238U and 232Th can cause severe radiation damage to the human respiratory system.