Natural and Anthropogenic Radionuclides in Atmospheric Air and Assessment of Inhalation Dose over Brick Field Areas, Dhaka, Bangladesh

Abstract

The concentrations of natural and anthropogenic radionuclides in the atmospheric air over the coal-fired brick activity at the locations of Dhamrai, Savar, and Ashulia in Dhaka, Bangladesh, were measured. High-resolution HPGe gamma-ray spectrometry was used for analyzing 18 particulate samples collected from this area. The identified radioisotopes were ²²⁶Ra, ²³²Th, ¹³⁷Cs, and ⁴⁰K. The measured activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K ranged from 0.016 ± 0.002 to 10.1 ± 2.2, from 0.006 ± 0.002 to 1.8 ± 1.6, and from 1.2 ± 0.06 to 2.4 ± 0.08 mBq/m³, respectively, with the average values of 3.0 ± 0.7, 0.63 ± 0.4, and 1.1 ± 0.04 mBq/m³, respectively. The activity concentrations of ²²⁶Ra and ²³²Th exceed the word average values in atmospheric air. Anthropogenic radiocesium (¹³⁷Cs) was identified in several air samples. The average activity concentration of ¹³⁷Cs was found to be 0.026 ± 0.003 mBq/m³. The order of the radionuclides present in the air particulate matter is ²²⁶Ra > ²³²Th > ⁴⁰K > ¹³⁷Cs. The total annual effective inhalation dose due to natural radioisotopes was found to be 93 and 27 μSv/year for adults and infants, respectively, which was below the ICRP permissible limit of 2.4 mSv/year. The main contributor to the inhalation dosage in both adults and infants was ²³²Th.