Characteristics of volatile organic compounds during haze episode in Foshan City

Volatile Organic Compounds (VOCs) in Foshan City were investigated in December 6 to 30 2008.The concentrations of VOCs in haze days were significantly higher than those in no-haze days. Toluene (68.93μg · m^-3 ± 37.78μg · m^-3) was the most abundant compound of VOCs in haze days and i-pentane (20.59μg · m^-3 ± 14.28μg · m^-3) was the most abundant compound in no-haze days, respectively. During haze episodes, the diurnal variations of alkanes and alkynes were not significantly; however, alkenes and aromatic hydrocarbon decreased significantly at noon. During no-haze episodes, the diurnal variations patterns of VOCs were stable. Propylene-equivalent concentrations in haze days were significantly higher than those in no-haze days, toluene was the most abundant compound of Propylene-equivalent concentration in haze days, followed by propene and ethene; propene was the most abundant compound in no-haze days, followed by ethene and 1-butene. High concentration of benzene (18.1μg · m^-3) in haze days posed a great health threat to public in Foshan city. Both diurnal variation of VOCs and measured ratios indicated vehicular emissions acted as the main sources of most VOCs and other sources like solvent application also contributed to VOCs (benzene and toluene).