A 10 month monitoring program of volatile organic compounds in various districts of Nanjing was performed in 2001. The air samples were analyzed by a system consisting of a thermal desorption, gas chromatography and mass spectrometry. Totally 189 volatile organic compounds were detected, among which 39 were aromatic compounds, 51 were alkenes, and many were oxygenated compounds such as alcohol, ketone, aldehyde, etc. Particularly, benzene, toluene, ethylbenzene and xylene had higher concentrations, the annual averages of benzene, toluene, ethylbenzene and xylene values being 9 04, 10 22, 3 57 and 5 04μg·Nm -3 respectively. The pollutants apparently illustrated the characters of districts. The highest concentrations of most volatile organic compounds species, especially benzene, toluene, ethylbenzene and xylene were found in the traffic district. The concentration of volatile organic compounds in the atmosphere was sensitive to the wind speed and temperature. So the pollution with volatile organic compounds was the most serious in November among the sampling period in the study. The ratios among benzene, toluene, ethylbenzene and xylene and their correlations suggested that vehicular emission was the dominant source of volatile organic compounds in Nanjing.
