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.