Urban particulate matter (PM10-PM2.5 and PM2.5) from Athens (Greece) atmosphere, primarily investigated by SEM-EDS, was further studied in the FLUO and SUL-X beamlines of ANKA Synchrotron facility (KIT, Germany). The SR mu-XRF study showed both geological (e.g. Ca-Ti, Ca-K and Ca-Sr-K-Rb) and anthropogenic particles exhibiting heavy metal combinations such as Fe-Co, Fe-Co-Cu-V and Zn-V. It was also revealed that very hazardous metalloids and heavy metals, namely As and Pb, are concentrated in isolated respirable (PM2.5) microparticles. It was attempted to investigate the oxidation state of As by means of mu-XANES. The As K-edge XANES spectrum of the sample shows a main peak at about 11.874 key which matches adequately with the As(V) reference spectrum but part of the As seems to have a lower oxidation state (most probably As(III)). This is the first non-bulk study with regard to the partitioning and solid-state speciation of hazardous chemical elements in urban atmospheric microparticles from greater Athens area, rated as an alpha-world city with a population of ca. 4 million people.