Assessment of natural radioactivity levels and potential health risks around coal fired brick kilns of twin cities Rawalpindi and Islamabad, Pakistan

In this study, the concentrations of radionuclides ( 226 Ra, 232 Th, and 40 K) in feed coal, bottom ash, and soil samples have been analysed by high purity germanium (HPGe) based gamma spectrometry system for two brick kilns sites, located at Islamabad and Rawalpindi, Pakistan. An assessment of the potential radiological health impact of these brick kilns on the general public has also been investigated. Samples of feed coal, bottom ash, and soil were collected in December 2020 from the brick kilns located at Sher Dhamial (Islamabad) and Rawat (Rawalpindi). The increased natural radioactivity levels were observed in soil samples collected from the proximity of brick kilns with a maximum concentration of 226 Ra, 232 Th, and 40 K as 62.70 ± 5.70 Bq kg −1 , 98.00 ± 2.60 Bq kg −1 , and 567.80 ± 37.00 Bq kg −1 respectively. The decrease in radioactivity levels with the increase in distance from the brick kilns indicated that both sites have elevated radionuclides levels due to the deposition of fly ash released from brick kilns. The average values of radiological parameters such as air-absorbed dose rate, outdoor annual effective dose equivalent, radium equivalent activity, and excess lifetime cancer risk were estimated to be 55 nGy h −1 , 0.07 mSv y −1 , 117 Bq kg −1 , and 0.24 × 10 −3 respectively. We conclude that the operation of these facilities increased radionuclides concentrations at nearby distances. Potential radiological concerns exist for the coming years, if these facilities continue their operations. It is suggested that the release of fly ash discharges to the environment may be reduced, and a periodic monitoring program may be established to protect the public residing in the vicinity of such facilities. This study could serve as a baseline for future epidemiological studies and radiological monitoring initiatives for the coal industry in Pakistan.