In January 2013,several of the most severe haze events on record swept across most of east-central cities and covered a quarter of the total land area in China.Using size-resolved filter sampling and chemical characterization,high concentrations of toxic metals were found in both fine and coarse particles in Beijing during the extreme haze pollution events.We also show that the mass concentration peak of Cu,Pb,Zn,Cd and K in particles shifted from 0.43–0.65 μm on clean days to 0.65–1.1 μm on lightly hazy days and to 1.1–2.1 μm on heavily hazy days.On the regional scale,however,Beijing was not the only one hotpot subject to heavy metal pollution.Through a long-term and multi-site observation,we identify highly elevated levels of heavy metals in megacities and industrial areas in Beijing–Tianjin–Hebei urban agglomeration compared to background area,with the annual mean values of As,Pb,Ni,Cd and Mn exceeding their acceptable limits of the WHO.In addition,the total deposition flux of Pb observed at a forest site in the region was twice that of the critical load(7.0 mg m?2 yr?1)calculated Dutch forest soils.Furthermore,atmospheric inputs of Cu,Pb,Zn,Cd,As and Se were of the same magnitude as their increases in the topsoil of agricultural systems.The findings generate great concerns over the potential risks of airborne heavy metals to human health and the environments.