From the 20th to the 25th of September 2009 in Langen (DE), 4 national reference laboratories (NRL) of AQUILA network and 3 laboratories of the World Health Organisation (WHO) Euro-Region met for an interlaboratory comparison exercise (IE) to evaluate their proficiency in the analysis of inorganic gaseous pollutants covered by European Air Quality Directives (SO2, NO, NO2 and O3).
Most of the laboratories participating in the IE used automated CEN reference methods, which are mandatory in the EU, while some laboratories of the WHO Euro-Region performed analysis using manual methods.
In this report proficiency evaluation was made at different degrees for each laboratory taking into account the differences in the methodologies and the completeness of the information provided by participants. For the laboratories who expressed their uncertainty, performance was evaluated using two criteria, providing information on their proficiency to the European Commission and supporting the national quality control systems.
In terms of criteria imposed by the European Commission (that are not mandatory for WHO laboratories), 71% of the results reported by National Reference Laboratories (AQUILA network) were good both in terms of measured values and reported uncertainties. Another 23% of the results had good measured values, but the reported uncertainties were either too high (19%) or too small (4%). There were no questionable nor unacceptable values.
AQUILA laboratories presented good comparability among participants for NO2, O3, and SO2. The relative reproducibility limit for NO was above the objective deriving from the standard deviation for proficiency assessment.
For WHO laboratories using automated techniques, the results are satisfactory for SO2, NO2 and NO measurement methods, while one laboratory needs further investigation of their O3 measurements.
The laboratory using manual methods presented results comparable to those of the automated methods for NO and O3 but there were questionable results for NO2 and SO2 and unsatisfactory results for NO2.JRC.DDG.H.4-Transport and air qualit
