Determination of aromatic hydrocarbons in urban air of Rome

Aromatic hydrocarbons were measured in Rome during 1992–1993 by means a differential optical absorption spectrometer (DOAS) and an automatic gas chromatograph (VOC analyzer). The mean distribution of aromatic hydrocarbons was: benzene 12.6%, toluene 35.4%, and remaining species 42%. The mean yearly concentrations of toluene (128 and 138 μg m−3) were 2–3 times higher than those of benzene (40 and 47 μg m−3). The highest concentrations of aromatic hydrocarbons were measured during the stagnant winter period. The diurnal behavior of aromatic hydrocarbons suggests that motor exhaust emissions are their dominant source. The different reactivities of benzene and toluene during photochemical smog episodes were discussed.