A comparison of automated measurements of air quality near Valthermond (NL) in 2004

In 2004 a simultaneous measurement programme was set up between the German LUEN and the Dutch RIVM to obtain an international validation of the results. The programme took place at a rural station near Valthermond, in the northeast of the Netherlands. This report states the results from the calendar year 2004 for the components PM10, NO, NO2, O3 and NH3. The differences observed were mostly within acceptable limits and could be explained. However the differences for O3 cannot be fully explained and this requires further attention. The programme led to a constructive improvement in the quality of the data produced by each institute and showed us how to improve the international comparability. Further much was learned from the experiences exchanged. The programme will be continued at the Valthermond site in 2005 to investigate the underlying causes in the differences and to resolve these.