European intercomparison workshops on air quality monitoring. Vol. 2 Measuring of CO, NO, NO_2 and O_3

This report presents the results of three European Intercomparison Workshops on Air Quality Monitoring (CO, NO, NO_2, and O_3) conducted in April 1995 and in April and September 1996 by the WHO Collaborating Centre for Air Quality Management and Air Pollution Control in co-operation with the central laboaratory of UBA Pilotstation in Offenbach/Main, Germany. These Workshops were a contribution to ongoing quality assurance and quality control activities in air quality monitoring within the WHO European Region. Fifteen institutes used the opportunity to compare their measurement methods (4 manual methods and 26 automatic methods) and analytical standards for ambient air monitoring of carbon monoxide, oxides of nitrogen and ozone. Calibrations were done by using certified reference materials (CRM) and by carrying through suitable independent calibrations. The results were expressed as concentrations over 30 minutes. The main result of altogether 122 intercomparison runs at the three Workshops is that agreement within +/-10% of the given concentration was reached by all laboratories. 93% of the participating laboratories were even able to achieve a result within +/-5% of the given concentrations. Additionally, one sampling period of 24 hours was performed for NO_2 during the Workshop in September 1996. Except one deviation of 5.5% all averages of the 24 hours run were within a tolerance of +/-5% from the target value. All applied methods could be recommended as suitable methods for future air quality measurements in the WHO European Region. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman