Benzene from traffic

5. Conclusions

Benzene in petrol

The reductions of the benzene content in crude and retail petrol have been documented by direct analysis of samples from the petrol terminals of the two Danish refineries, Statoil in Kalundborg and Shell in Fredericia. The benzene content was reduced from approx. 3.5 % to approx. 1 % at both refineries. Statoil reduced the benzene content to 2% already in 1995, but both refineries reduced the benzene content to 1 % during the summer 1998. the total content of aromatic VOC’s was not changed significantly in this period.

Benzene emissions

The decreasing emissions and air concentrations of CO and NO_x were a consequence of the increasing number of petrol cars with three-way catalysts, which is 60-70% in 1999. The emissions and air concentrations of benzene were reduced much more, corresponding to the above reductions in benzene content in petrol sold in Denmark. The influence of other aromatic compounds in petrol could not be detected and is probably not important. The benzene concentrations in urban air are expected to decrease further the coming years corresponding to the increasing number of cars with catalysts.

Acknowledgement

The presented work was partly funded by the Danish Ministry of Traffic under the project Surveillance of the Contribution from Traffic to Local Air Pollution Levels in Denmark and partly by the Danish Environmental Protection Agency. The Danish Road Directorate provided traffic counts obtained within the project Air Pollution from Traffic in Urban Areas under the framework of the Danish National Environmental Research Programme 1992-1996. A major part of the project is funded by the Danish Agency of Environmental Protection; Erik Iversen is acknowledged for his active participation in discussions during the project. Flemming Ludvigsen from Oliebranchens Fællesrepræsentation is also acknowledged for providing good contacts to the refineries, which are acknowledged. Data were provided from the National Air Quality Monitoring Programme, especially by Kåre Kemp, and the operation and calibration of the BTX-monitor were carried out by Carsten Stenholt, Kit Granby and Hans Nielsen. Their contributions are acknowledged.