Article Highlights• Lead concentration showed a decreasing trend during the entire studied period • The horse chestnut leaves showed good response to changes in trace element atmospheric concentrations • Different sources of trace elements in ambient air and in horse chestnut leaves were observed • During the studied period, traffic was one of the major sources of the measured elements in Belgrade • The trace element concentrations in PM10 were below the limits of Serbian and EU legislation AbstractIn this study, airborne particulates (PM10) and leaves of horse chestnut were collected at selected urban sites in Belgrade, Serbia, in years 2006, 2009 and 2012. All samples were analysed for trace element concentrations of As, Cd, Cr, Ni and Pb. It was found that, during the study period, the differences among PM10 mass trace element concentrations were not considerable, and that the measured mass and trace elements concentrations were below the Serbian and EU legislation limits. The highest values of trace element concentrations in leaves were observed in year 2012, with the exception of Pb. Lead concentration had a decreasing trend during the whole studied period, in both PM10 and tree leaves. Since leaded gasoline was banned in 2011, a possible reason could be an increasing number of vehicles using unleaded kind along the previous years. Although trace elements in horse chestnut leaves were accumulated only during the summer season, horse chestnut leaves showed good response to changes in trace element atmospheric concentrations. However, seasonal variability was evident in trace element source apportionment due to the lack of stationary heating system influence. The principal component analysis showed that during the studied period, one of the major sources of the measured elements was fossil fuel combustion.