Benzene emission from the actual car fleet in relation to petrol composition in Denmark

The present study covers an investigation of the trends in air pollution le vels of benzene in Danish cities and their relationship with the benzene co ntent in petrol. Petrol samples from the two refineries in Denmark as well as sold petrol from some representative Danish petrol stations were analyse d. The benzene content in Danish petrol was reduced from 3.5% for 95 octane prior to 1995 to approx. 2% in 1995 and further to 1% in 1998. Air quality measurements of aromatic VOC are available from two Danish cities; Copenha gen since 1994 and Odense since 1997. Measurements of benzene, CO and NO, f rom these two locations were analysed using the Operational Street Pollutio n Model (OSPM) and trends in the actual emissions of these pollutants were determined. It is shown that the decrease in both the concentration levels and in the emissions was significantly larger for benzene than for CO and N O,. The decreasing trends of NO, and CO could be explained by the increasin g fraction of petrol-fuelled vehicles with three way catalysts (TWC). The m uch steeper decreasing trend for benzene can most likely be attributed to a combination of the effect of the increasing share of the TWC vehicles and a simultaneous reduction of benzene content in Danish petrol. The reduction of benzene concentrations and emissions is observed despite that the total amount of aromatics in petrol has increased slightly in the same period. ( C) 2001 Elsevier Science Ltd. All rights reserved.