Central calibration laboratory (CCL) for halogenated VOCs

Since June 2023, the Federal Institute of Metrology METAS has been the globally recognised central calibration laboratory (CCL) of the Global Atmosphere Watch (GAW) programme for halogenated volatile organic compounds (VOCs).

Why halogenated VOCs are measured

The atmosphere contains well over 30 different halogenated VOCs. Some of these contribute significantly to global warming and partly to the depletion of the stratospheric ozone layer. Others break down into products that harm the environment. Accurate and comparable measurement of all halogenated VOCs in the atmosphere is critical to deepening our understanding of climate change and defining and verifying measures.

Global Atmosphere Watch (GAW) Programme

The GAW Programme of the World Meteorological Organization (WMO) is a partnership involving over 100 countries. The aim is to measure the chemical composition of the atmosphere in a long-term and comparable manner with a global network of measurement stations. To achieve this, high-quality reference standards are required, which are provided by the GAW central calibration laboratories (CCLs). By assuming the role of CCL, METAS has laid the foundation for ensuring that halogenated VOCs can be measured comparably worldwide within the GAW network.

Duties of METAS as a CCL

METAS provides SI-traceable reference gases for the following ten halogenated VOCs for the GAW network:

  • HFO-1234yf
  • HFC-125
  • CFC-13
  • HCFC-132b
  • 1,2-dichloroethane
  • HFO-1336mzz(Z)
  • HFC-32
  • HFC-365mfc
  • CH2Cl2
  • CCl4

The specific tasks of METAS include:

  • the provision and maintenance of SI-traceable reference gas mixtures for calibrations
  • supporting GAW stations with questions about passing on the reference values and calibrating the instruments and measurement uncertainty
  • in close cooperation with the operators of the measuring stations, as part of international projects: the development of new reference gases for substances for which there are currently no SI-traceable references

This work is being carried out with financial support from MeteoSwiss.

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