The size distribution of total and water-soluble elemental concentrations in six particle sizes <0.49, 0.49-0.97, 0.97-1.5, 1.5-3.0, 3.0-7.2, and 7.2-30 μm was investigated in Thessaloniki area, N. Greece, at two sites representing urban-traffic and urban-background character during the cold and warm period. The elements As, Cd, Cr, Cu, Pb, Ni, Zn, Ru, and Ir exhibited their highest mass portion in the fine particle mode (0.97-1.5 μm), whereas Al, Ba, Ca, Fe, and Mn occurred predominately in the coarse particle mode (3.0-7.2 μm). The water-soluble elemental fractions exhibited significant spatiotemporal variations and particle size dependence. Possible non-carcinogenic and carcinogenic risks associated with inhalation of particle-bound elements based on total and water-soluble concentrations were in acceptable levels. However, the cumulative risk for all potential particle-bound constituents has to be considered.