This European Standard specifies specific performance requirements and test methods under prescribed laboratory and field conditions for diffusive samplers used for the determination of the concentration of gases or vapours in ambient air. Such requirements apply to all diffusive samplers, irrespective of the physical nature of the rate-controlling process and irrespective of the nature of the sorption process and the analytical determination. This standard applies to all stages of the measuring procedure, including transportation and storage of the sample where appropriate. This standard applies to measuring procedures with separate sampling and analysis stages, and also to direct-reading devices. This European Standard is applicable to diffusive samplers according to 3.6 of EN 13528-1:2002. This European Standard should enable manufacturers and users of diffusive samplers to adopt a consistent approach to sampler validation and provide a framework for the assessment of sampler performance against criteria specified in EN 13528-1. It is the responsibility of the manufacturer or of those who assemble the diffusive samplers to ensure that the sampler complies with the data quality objectives given in this European Standard. For the purpose of demonstrating compliance with data quality objectives prescribed for methods to be used in support of the Council Directive on Ambient Air Quality Assessment and Management, this part of EN 13528 provides the relevant requirements and test methods for the determination of measurement uncertainty. As indicated in 6.5.2 to 6.5.4, some of these procedures are to be undertaken by a single representative laboratory, some by several laboratories in an interlaboratory trial, and some by the laboratory implementing the method. This division of responsibility is in accordance with Table 1 of CEN Report CR 14377:2002 [3].