Intercomparison Exercise for Ambient Mass Concentration Measurement of Atmospheric Particulate Matter by Gravimetric Samplers
Over the last decades epidemiological studies conducted in many countries around the world, observed associations between ambient particle mass concentrations and human health risks. EU has set since 1999 air quality standards (1999/30/EC) for PM10 particles. Many countries perform PM10 measurements and operate air monitoring networks, thus it is necessary to estimate the uncertainty of PM10 measurement in order the results to be comparable. An inter-laboratory comparison of PM10 measurements was held in the ground of NCSR “Demokritos”, in Athens, Greece. The aim of the campaign was to investigate if equivalent PM10 gravimetric samplers produce equivalent results and to estimate the uncertainty of the measurement. The 20 days measurement program included 24hr measurements of PM10 mass concentration, using gravimetric sampling instruments. The intercomparison measurements were carried out between the 29/9-29/10 2010. Thirteen laboratories participated in the campaign with a PM10 sampler (Unit), which is represented by a unique number (e.g. Uj, where j represents the number of the unit - not related to affiliated institutes). All the samplers had been placed on a measuring platform, at the grounds of the N.C.S.R "Demokritos". Participating measuring systems were based on the same principals for size selection of the PM10 fraction, filtration of the particles and flow measurement. Size selection inlets operated by impaction, teflon nuclepore and quartz filters were used and flow was controlled by orifice systems and/or measured by dry gas meters. The method of gravimetric measurement and sample handling was in Moreover, the Z-score was also calculated in order to assess the comparability of the candidate samplers with the reference value (average PM10 mass concentration). Considering that a I Z-score I <2 implies a satisfactory comparability (EN 12341, 1998), 8% of the results of measurement was outside that interval. The validation and the delivery of the results were performed by the “Greek Atomic Energy Commission, (GAEC)”.