Das Projekt "VOTALP I + II - Vertikaler Ozontransport in den Alpen (Environment and Climate FP4)" wird vom Umweltbundesamt gefördert und von Universität für Bodenkultur Wien, Institut für Meteorologie und Physik durchgeführt. The EU research project VOTALP investigated transport and formation of ozone in the Alps, focusing on processes which can cause increased ozone concentrations, namely stratospheric intrusions, horizontal advection of polluted air, and in-situ production of ozone due to emissions in Alpine valleys. It was found that the average ozone concentrations in the Alpine area seem to be mainly determined by emissions in the surroundings and horizontal advection in the lower troposphere. Peak values are mostly ascribed to horizontal transport of polluted air, for instance during foehn, or stratospheric intrusions. Due to the enhanced deposition of pollutants the Alps probably act as a net sink for photo-oxidants. This implies a high impact of pollutants on the sensitive Alpine ecosystems, since deposition mainly means interception by plants.