A Technical Review of the Feasibility of Producing Certified Reference Materials for the Measurement of Gaseous Pollutants in Ambient Air

Abstract

Within the frame of the EU sponsoredproject ‘Cermatair’ (CertifiedReference Materials for the Measurement of Gaseous Pollutants in Ambient Air, contract G6RD-CT-2001-00517) the feasibility of preparing andcertifying reference materials for the measurement of sulphur dioxide, nitrogen dioxide, carbon monoxide and benzene in ambient air was studied. The project focused on measurements at concentration levels corresponding to limit values given in EU Ambient Air Quality Directives andcovered reference materials for the reference methods specifiedin these Directives and for alternative methods based on diffusive sampling. State-of-the-art technologies for the production and certification of the reference materials were identified through literature surveys. Limited batches of reference materials were preparedand , wherever appropriate, testedfor homogeneity. The reference materials were subsequently tested in small-scale external verifications, performedby 2–4 laboratories other than the preparation laboratory, aimedat identifying possible discrepancies between concentration values from the preparation processes and experimental values. The results of these verifications revealedpossible mechanisms of certification (basedon preparation or measurements). The remaining materials were subjectedto a one-year stability study.JRC.H.4-Transport and air qualit