One of the principal concerns in recent years regarding the atmospheric environment has been the formation of ozone and other photo-oxidants over much of Europe in the summer. Ozone is formed in the atmosphere by a complex series of chemical reactions in the presence of sunlight from volatile organic compounds and nitrogen oxides. As the reactions take place in air flows determined by the detailed meteorological situation, the measurement, interpretation, understanding and modelling of the levels, fluxes and origins of the ozone are extremely difficult. The present volume reviews several of the currently important questions and presents detailed reports from investigators all over the continent. As such, it provides insight into the current scientific views about ozone in Europe.