Climate change - mediated atmospheric 210Po and 210Pb distribution: How significant can it be for the inhalation dose to humans?

Abstract

The concentration of 210Po and 210Pb in vegetation, and their transfer from soil to vegetation and via aerosol deposited on foliage are well established. The available data show significantly higher levels of these radionuclides in ash from forest fires and aerosols downwind from industrial sites. The climate change-induced hot and dry conditions promote the spread of forest fires, which burn huge areas. On average, over 10 million hectares are reportedly lost annually. Large-scale forest fires and fossil-fuel and coal-operated Power and Desalination Plants are very likely to result in the dispersion of 210Pb and 210Po into the regional aerosol; such an effect has already been observed due to fires in Ukraine, Belarus, and Russia, which have led to the dispersion of 137Cs over large parts of Europe. We have measured elevated levels in Kuwait, and similar observations have been reported from Portugal. The higher levels of 210Po in PM2.5 raise a serious concern about an increased inhalation dose humans could receive. Our estimate shows that humans in areas affected by forest fires might receive a dose equivalent to 2 µSv d-1, which is significantly higher than 0.099 µSv d-1, the dose a person gets from smoking a packet of cigarettes daily. We propose that size-fractionated aerosol sampling should be taken up in regions affected by forest fires and industrial activities that add 210Po to the atmosphere in order to obtain a robust inhalation dose assessment and issue informed advisories to the public.