The primary aims of the VPEC are as follows:

- aid members to make the most appropriate choice of instrument to conduct valid measurements;

- ensure that particle-measurement data are accurate and precise;

- advocate the adoption of well-defined uncertainties for all particle measurements; develop and validate traceable calibration procedures/techniques.

Studies of number calibration standards and related methodologies developed during the course of the VAM work have proved particularly important in validating particle-size measurements of vehicle emissions.

Another focus of effort has been the development of a standard to calibrate particle-number measurement instruments, and the preparation and presentation of a paper describing this work to specialists at the European Aerosol Conference (held in Dublin, 3�8 September 2000). Members of the VAM team have also participated at other appropriate national and international meetings throughout the year.