Search

CFCs (chlorofluorocarbons) and other strong ozone-depleting halogenated organic trace gases were used in numerous industrial, household and agriculture applications. First atmospheric measurements of CFCs were performed in the 1970s, well ahead of the detection of the ozone hole in the 1980s. The continuous observation of these ozone-depleting substances (ODSs) is crucial for monitoring their global ban within the Montreal Protocol. In addition, also HFCs (fluorinated hydrocarbons) are measured, which were introduced as substitutes of ODSs and are potent greenhouse gases. Since 2000, Empa continuously measures more than 50 halogenated trace gases at the high-Alpine station of Jungfraujoch (3850 m asl) as part of the global AGAGE network (Advanced Global Atmospheric Gases Experiment). Jungfraujoch is the highest location worldwide where such measurements are performed, and the site where several of these compounds were measured in the atmosphere for the first time. The measurements at Jungfraujoch and at other globally well-positioned sites serve as an early warning system, i. e. before potentially harmful halogenated organic substances can accumulate and detrimentally affect the natural environment.

Man-made halocarbons have a considerable impact on the environment. Chlorine- and bromine-containing organic compounds such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are responsible for the decline of stratospheric ozone and their use has therefore been regulated in the Montreal Protocol. Fluoro-containing halocarbons are not regulated within this treaty, but as all halocarbons act as greenhouse gases, this group of compounds was included in the Kyoto Protocol. Halogenated ozone destroying CFCs and chlorinated solvents were continuously measured in Switzerland at a suburban site near Zürich (Dübendorf) from 1994 until 2000 and since 2000 at the high alpine site of Jungfraujoch together with all greenhouse-active halocarbons. Furthermore, all anthropogenic halocarbons were measured in a campaign in Dübendorf in 2002. The analysis of the measurements confirms that a substantial decline of their emissions took place as a consequence of the Montreal Protocol. On the other hand, the concentration of substitutes such as hydrofluorocarbons (HFCs) increased dramatically. Linking continuously measured time series with meteorological information allows an estimation of regional emissions of the regulated compounds for Switzerland. In contrast to trade survey statistics or inventories, this method is an efficient tool to track the development of diffusive emissions of substances in long term usage such as foams and refrigerant systems.