evaluation of volatile organic compounds levels inside taxis passing through main streets of tehran

air quality inside commuting vehicles has seldom been evaluated in iran. accordingly, this study investigates the levels of benzene, toluene, ethylbenzene and xylene (btex) during workdays characterized by heavy traffic inside taxis in tehran- iran between may 2009 and october 2010. the totals of 35 personal samples were collected onto solid sorbent tubes and the concentration of volatile organic compounds (vocs) were analysed by gas chromatography technique equipped with flame ionization detector (gc/fid). the arithmetic means of personal monitoring of btex concentrations inside vehicles were found 72.77, 93.91, 9.90 and 4.23 ppb respectively. exposures to btex during traffic flow in the evening were considerably higher than those measured in the morning. the weekdays btex level of inside vehicles illustrated significant differences among the studied months ( p <0.05). the btex concentration ratios were estimated to be related to traffic emissions and similar for all the surveyed routes. in conclusion, the results confirmed that the emission of btex and their concentrations being highly associated with traffic jam as well as changes in meteorological conditions.