Critical aspects of the uncertainty budget in the gravimetric PM measurements

The interest in particulate matter (PM) exposure studies leaded the regulatory authorities and the air quality management community in updating new air quality standards. In order to characterize the current exposure experienced by people, measurement should be carried out also taking into account periodic PM concentration fluctuations. For this purpose continuous or semi-continuous measurement techniques were developed even if the reference method used to measure the air quality standards is still based on the gravimetric analysis of particle collected through filtration technique over a period of 24 h. In this work the authors carried out a metrological characterization of the gravimetric method in measuring PM concentrations. The critical aspects of the technical standard in evaluating the uncertainty budget of PM measurement are stressed and the influence of single uncertainty contributions to the combined uncertainty is also shown. Finally, a comparison between European and US standards in PM measurement is made.