Velocity-dependent benzene emission factors of three-way catalyst passenger cars and light duty vehicles from time-resolved exhaust gas analysis

Time-resolved Chemical Ionisation Mass Spectrometry (CI-MS) has been used to investigate the benzene emission profiles in automotive exhaust during transient engine operation. Representative petrol-driven passenger cars and light duty vehicles with model years 1991 to 1996 have been selected from the Swiss car fleet and were measured on the chassis dynamometer at the Swiss Federal Laboratories for Materials Testing and Research (EMPA). The benzene emission characteristics of a fleet of 20 passenger cars (1.3-5.21), eight light duty vehicles (2.0-2.41) and one conventional vehicle (1.41) have been determined. A set of seven driving cycles, including the European Driving Cycle (ECD), the US Urban (FTP 75), the Highway and four additional driving cycles have been investigated by CI-MS. Velocity-dependent emission factors for the individual vehicles as well as for the different vehicle classes were determined by a statistical analysis of the corresponding emission data.