Evaluation of the laboratory comparison exercise for SO2, CO, O3, NO and NO2 26th- 29th September 2011 : EC harmonization program for air quality measurements

From the 26th to the 29th of June 2012 in Ispra (IT), 9 Laboratories of AQUILA (Network of European Air Quality Reference Laboratories) met for a 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, 86% of the results reported by AQUILA laboratories were good both in terms of measured values and reported uncertainties. Another 13% of the results had good measured values, but the reported uncertainties were either too high (7.9%) or too small (5.4%). One value fell in category 5 (0.3%) and one in 7 (0.3%). Comparability of results among AQUILA participants at the highest concentration level, excluding outliers, is acceptable for all pollutants. Only CO measurement methods showed less satisfactory results at concentrations around 3μmol\mol.