Betrouwbaarheid van PM10-metingen in Nederland: een samenvattend overzicht

The FAG-Eberline 62I-N automatic beta-dust monitors operate within the framework of the Netherlands National Air Quality Monitoring Network (LML) to carry out PM10 measurements. A correction factor of 1.33 is adopted to compensate the 25% underestimation when using the beta-method compared to the PM10 reference method (e.g. Klein Filter Gerat). Several series of laboratory and field experiments were performed to determine quality of the PM10 measurements and to explain the use of the correction factor.Inlet heating and sampling on a relative warm filter causes some of the aerosol to vaporise. This seems to justify the compensation for the loss of ammonia nitrate aerosol and organic aerosol. However, the experiments also show the correction to be location dependent. The factor of 1.33 is too high for agricultural areas, where ammonia levels are relatively high and organic aerosol levels relatively low, and too low for urban areas with considerable traffic. For this reason we have taken the happy medium. The differences found between the measurements and the models can thus be partially explained by this discrepancy between agricultural and urban areas.