The main objective of the workshop was to increase our knowledge of ozone formation and distribution in the troposphere, its relation to precursor (NO and HC species) distribution, how it is affected by transport processes in the troposphere, and to show how the increasing levels of ozone can cause environmental problem. The focus was on the interaction of ozone on regional and global scales. There is mounting evidence that such interactions occur and that the ozone levels are increasing in most of the Northern Hemisphere tropo- sphere. A likely source of ozone increase is human activity. As...