English 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.