Traffic-related exposure to benzene and toluene

Monoaromatic hydrocarbon concentrations were measured within moving vehicle s and at a fixed point on the road. Pedestrian exposure to these aromatics was also assessed by sampling along busy roads at heights of 1 m and 1.5 m. A comparison of in-vehicle and out-of-vehicle concentrations showed little difference, which indicated that the main source of in-vehicle pollution w as the surrounding vehicle emissions. Roadside and in-vehicle and out-of-ve hicle concentrations were typically several times higher (in congested road s) than those measured at a background monitoring station based in a suburb an region of Birmingham (Ward End). Pedestrian exposure was also greater th an background concentrations. Concentrations were greater at a height of 1 m than at 1.5 m, owing to the closer proximity of vehicle exhaust pipes, bu t only by a factor of 1.21 for benzene and 1.19 for toluene.