Evaluation of the laboratory comparison exercise for NO, NO2, SO2, CO and O3 : 4th-9th of October 2015, Langen (D)

From the 4th to the 9th of October 2015 seven Laboratories of the World Health Organization (WHO) European-Region met for another joint JRC-ERLAP/WHO inter-laboratory comparison exercise (IE). They met at the National Air Quality Reference laboratory at the German Federal Environment Agency in Langen, Germany, to evaluate their proficiency in the analysis of inorganic gaseous pollutants (NO, NO2, SO2, CO and O3) covered by the European Air Quality Directive 2008/50 EC and recent revision 2015/1480/EC. The proficiency evaluation, where each participant's bias was compared to two criteria, provides information on the current situation and capabilities to the European Commission and can be used by participants in their quality control system. On the basis of criteria imposed by the European Commission, 73.2% of the results reported by the laboratories were good both in terms of measured values and reported uncertainties. Another 23.9% of the results had good measured values, but the reported uncertainties were too high and for 0.7% of the values the uncertainty was underestimated. 1.4% of the values were questionable and 0.7% were unsatisfactory. Comparability of results among participants (reproducibility) at the highest concentration level, excluding outliers, is acceptable for CO and SO2 measurements while NO2, NO and O3 one showed less satisfactory results.