Polycyclic aromatic hydrocarbons in ambient air: A view of some obtained results in Spain in the last years

The first studies were focused to analyse the polycyclic aromatic hydrocarb ons (PAH) in large cities, as Madrid and Barcelone, where there are many em ission sources in very little space producing a great environmental polluti on. These works have shown higher values during winter season in urban and industrial areas. PAH show much lower levels and less frequent concentratio ns in remote areas. Fossil fuel combustion emissions, those associated with gasoline and diesel vehicular traffic, are the main sources of PAH.