Abstract

This report summarises the main results presented during the most recent "Quadrennial Ozone Symposium", held in Charlottesville, Virginia, USA.At the symposium the knowledge on production, loss and transport of ozone in troposphere and stratosphere were highlighted. In the lower troposphere in the Northern Hemisphere ozone is increasing by 1 percent per year. Key questions are how this increase is connected with emissions of NOx, VOC, CH4, and CO, and the role of biomass burning in the tropics. Ozone is decreasing at a rate of 0.5 to 1.5% per year in the stratosphere. The research here is concentrated on the ozone loss in the Arctic regions and heterogeneous reactions on polar stratospheric clouds, background sulphate aerosols and the Pinatubo aerosols.