[en] Using cascade impactor sampling and PIXE analysis we have measured particle size distributions for approximately 15 elements in the Sao Paulo urban atmosphere. These elements, in our case, may be classified, according to their occurrence in fine or coarse aerosol log-normal modes, into three groups: (a) soil dust reference elements (coarse particle mode): Ti, Si and Ca; (b) anthropogenic fine particle mode: Zn, Br and Pb; and (c) mixed bimodal elements: S, K, V, Cr, Mn, Ni, Cu and Fe. All of the soil dust reference elements show consistently the log-normal parameters MMAD approx. 5.5 μm and sigmasub(g) approx. 3.2 (mass median aerodynamic diameter and geometric standard deviation, respectively). Enrichment factor calculations for Ti, Si, Ca and K in the coarse particle fraction (> 2 μmad), relative to Fe and the standard crustal aerosol values of Lawson and Winchester, show that Ti and Si are mainly soil derived while Ca and K may have significant industrial components in this particle fraction (i.e. coarse mode). The fine mode parameters for the other elements show variations with element suggesting different air pollution sources (such as motor vehicles, resuspended dust, refuse burning, industrial activities, etc.) and/or different chemical pathways, which presumably could be identifiable. For example, the modal parameters for group (b) are: Zn, MMAD = 0.9 μm, sigmasub(g) = 2.2; Br, MMAD = 0.5 μm, sigmasub(g) = 4.0; Pb, MMAD = 0.6 μm, sigmasub(g) = 3.0; thus suggesting a common source (automotive) for Br and Pb, unrelated to the source of Zn (possibly refuse burning). (orig.)