New European legislation and its relation to methods performance criteria and standardization.

In the European context, two new directives, in particular, are under development, namely a Chemical Agents Directive and an Ambient Air Directive. The first concerns the workplace and the second outdoor air, but both require an assessment of air quality and imply a requirement for actual measurement. If measurement results are to be comparable across Europe, there is also a requirement for standardization of such measurements, either as defined reference methods or as method performance requirements. The task of standardization in the field of measurement is ultimately the responsibility of the European Commission, but it usually devolves this responsibility to Scientific Expert Groups, reporting to the Commission, or to Technical Committees of CEN, the Comité Européen de Normalisation. The development of standard measurement procedures, ideally meeting the CEN performance criteria, is also the responsibility of ISO, the International Organisation for Standardisation. In practice, CEN TC 137 has developed method performance requirements for measuring workplace air quality and CEN TC 264 has developed reference methods for measuring ambient air quality. However, these approaches are not entirely incompatible, because in most cases a reference method can only be established if it meets certain performance criteria and equivalent procedures are allowed. Most methods actually adopted by CEN as reference methods have previously been standardized by ISO, but a few are being developed within CEN.