Measurements of aerosols, such as their optical and chemical properties, and particle number and mass concentrations, have a well-established place in atmospheric science. Similar measurements have also been made for many years in the context of air quality legislation, workplace exposure, vehicle emissions, and the characterisation of industrial nanoparticles. In the case of vehicle emissions, particle number concentrations have recently become part of regulatory requirements.
Several National Metrology Institutes (NMIs) have facilities and services that address some of these requirements, and comparisons have recently taken place to evaluate levels of mutual agreement, and thus start the process of putting metrological traceability for aerosol measurements on the same basis as for gas analysis measurements.
The GAWG workshop held at the BIPM on 15 April 2015 started with presentations from users including the atmospheric monitoring community (the World Meteorological Organization), an automobile manufacturer (BMW) and regulators (the OECD and the US Environmental Protection Agency). There were then contributions from eleven NMIs explaining their capabilities and planned work in the area.
There was much discussion at the workshop about the importance of measuring "black carbon". At present there is no consensus on the definition of "black carbon" which is measured by different techniques that work on different physical and chemical principles. The workshop agreed to set up a task group to identify the key technical issues that must be addressed to achieve worldwide comparability of black carbon measurements.
The workshop was organized by Oksana Tarasova (WMO), Christopher Zangmeister (NIST), Robert Wielgosz (BIPM), Paul Quincey (NPL), Yuri Kustikov (VNIIM) and Hanspeter Andres (METAS).