Po concentration in different size fractions of aerosol likely contribution from industrial sources.

Po, being a highly radiotoxic isotope, could contribute to significant inhalation dose to humans. This study establishes the first set of atmospheric Po data in aerosol samples collected across Kuwait. The primary focus of this study is to investigate spatio-temporal variability of atmospheric Po and assess its sources, including anthropogenic contributions. Measurements of Po in aerosols collected over a period of 23 months (January 2018-November 2019) from three different locations, i.e., a remote area (120 km) north of Kuwait City, Kuwait city and an industrial site (60 km from Kuwait City center). Specific activities of Po were determined in 3 different size fractions (0.39-2.5 μm, 2.5-10 μm and ≥10 μm) and the highest activity was observed in the fine fraction (PM) across all sampling stations during both the summer and winter seasons. The highest activities in all the size fractions were measured downwind of the Industrial site that houses oil refineries, cement factory and some other industries including a Power and Desalination Plant. In terms of temporal variations, higher summertime activities were observed across the spatial domain. Longer residence time of atmospheric Rn-produced Pb resulting in lower scavenging of atmospheric Pb, due to very little precipitation in summer, will result in higher atmospheric Po.