Nitrated-PAH in urban air of Italy as indicators of motor vehicle emissionand light-induced reactions

The presence of particle-bound nitrated PAH (NPAH) in the atmosphere has be en observed in urban areas of Italy. Milan appeared to be the most polluted city. Sites of different nature were investigated in Rome and its outskirt s. Particle-bound NPAH were modulated not only in concentration, but also i n the relative content of homologues, according to emission and in-situ gen eration mechanisms influencing the site. Despite that, direct release from motor vehicles was found less important than degradation of PAH with respec t to the presence of NPAH in the atmosphere. Concentrations of NPAH seemed to be capable to affect ambient air quality, due to strong mutagenicity of selected congeners.