Transport is very important for the economy and our welfare. However, transport also causes a lot of problems, including air pollution. Such problems should be taken into account, when making decisions. A prerequisite for doing so is, that the impacts are known, quantitatively measured and allocated to the different activities in transport. Furthermore, they should be transformed into monetary units to be used as a basis for cost-benefit analyses or as an aid for setting taxes and charges, that reflect the external costs. This book describes a methodology for calculating impacts of transport activities and external costs caused by air pollution and presents numerous applications of this methodology for different transport technologies, locations and policy case studies. The approach has been developed and results have been calculated within the research project 'ExternE Core/Transport', financed to a large extent by the European Commission, Directorate General Research. We would like to thank especially Pierre Vallette and Pekka Jarviletho from the EC for their advice and support. A considerable number of experts with expertise in the different disciplines of this highly interdisciplinary work contributed to this book. The editors would like to thank the authors (see list on p. XV) for their contributions; it is especially remarkable, that the authors helped to make this book an integrated whole instead of a number of independent contributions.