BTX measurements with diffusive samplers in the vicinity of a cokery: Comparison between ORSA-type samplers and pumped sampling

In the framework of new European directives in the field of ambient air qua lity assessment specific requirements for measurement methods for benzene w ill be defined and have to be met in the future. In a residential area in t he vicinity of a cokery a comprehensive monitoring programme for BTX compou nds (benzene, toluene, xylenes) was carried out with diffusive samplers. Me asurement results from 20 sites show a distinct spatial distribution of ben zene concentrations which is caused by the emissions of the plant. Comparis ons with two pumped measurement methods reveal excellent agreement in the c ase of benzene. An assessment of measurement uncertainty for the diffusive method is presented in terms of standard deviations from parallel measureme nts (precision) and by comparison with a reference method according to nati onal and international standards. Data quality objectives required by an up coming European directive for benzene can be met by diffusive sampling.