Das Projekt "Halogenated Greenhouse Gases by a Swiss MEDUSA" wird vom Umweltbundesamt gefördert und von Eidgenössische Materialprüfungs- und Forschungsanstalt, Abteilung Luftfremdstoffe,Umwelttechnik durchgeführt. The aim of CH-HALOMED is to install a measurement equipment to analyse halogenated greenhouse gases in the laboratory of Empa in addition to the continuously running identical system at Jungfraujoch (MEDUSA). This measurement equipment has been developeed by SIO in La Jolla (California) and is the main instrumentation used world-wide to perform state-of-the art measurements of halogenated greenhouse gases. The scientific goals of CH-HALOMED are to developing analytical methods for new halocarbons used in the industry and in consumer products and advance the sample trapping technology within the MEDUSA. Furthermore, the new system will allow sustaining the intercomparability within the European network: System for Observation of Halogenated Greenhouse Gases in Europe (SOGE) and its extension to China (SOGE-A) and linking of standards and scales at Jungfraujoch to those of AGAGE/NOAA. The instrumentation of CH-HALOMED will be used to analyse atmospheric halocarbons from international projects such as CARIBIC (air sampled by commercial aircrafts) and Antarctic samples by KOPRI (Korea Polar Research Institute) and NILU (Norwegian Institute for Air Research). Finally the MEDUSA system will be used for quantification of Swiss emissions of halogenated greenhouse gases by analysing air samples from the suburban station of Duebendorf (near Zurich). The context of CH-HALOMED is the global effort to assess the contribution of halogenated greenhouse gases to global warming. This is achieved by estimating global emissions of halogenated greenhouse gases (i.e. CFCs, HFCs, SF6) uisng their behaviour in the background air masses and to assess regional sources, using pollution events occuring at measurement sites in different continents. Furthermore, the MEDUSA system is extremely well-suited for detection of newly released industrial compounds in the atmosphere. The applicability of this concept has already been shown by Empa using existing equipments. With the new MEDUSA Empa has the possibility to advance in this field to faster reacting hydrofluorcarbons, which will be produced by industry in the next years. Although these compounds do have a minor influence on the global warming, their degradation products (i.e. fluorinated organic acids) could potentially affect aquatic bio-organisms.