Evaluation of the Laboratory Comparison Exercise for SO2, CO, O3, NO and NO2, Langen 23rd-28th October 2011 : EC harmonization program for air quality measurements

From the 23rd to the 28th of October 2011 in Langen (DE), 7 Laboratories of WHO/AQUILA (Network of European Air Quality Reference Laboratories) met at an laboratory comparison exercise to evaluate their proficiency in the analysis of inorganic gaseous pollutants covered by European Directive about air quality (SO2, CO, NO, NO2 and O3). 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, 59.4% of the results reported by the laboratories were good both in terms of measured values and reported uncertainties. Another 39.9% of the results had good measured values, but the reported uncertainties were too high and only 0.7% delivered questionable results. Comparability of results among participants at the highest concentration level, excluding outliers, is acceptable for CO and NO measurements while SO2, O3 and NO2 measurements showed less satisfactory results.