Comparison of Microscopic and Aerodynamic Particle Size for M201A Samples

Tim Vander Wood & Whitney Hill (MVA Scientific Consultants) and Jim Serne (TRC)

Stack Testing Lab

Cyclones are commonly used to collect PM10 and PM2.5 size fractions, under the assumption that they accurately separate out particles with diameters above and below 2.5 and 10 micrometers. We have analyzed cylcone fractions collected in the field by automated scanning electron microscopy, directly determining the particle diameters collected on each stage. Examination of these particles indicates that the particle sizes actually collected on each stage range far outside the listed particle size cutoffs. Reconstruction of the actual particle size distributions from the measured particle sizes and mass collected in each cyclone fraction indicates that significant errors may be present in the cyclone data, particularly in the PM2.5 fraction.

Comparison of Microscopic and Aerodynamic Particle Size for M201A Samples

CONCLUSION: Mass distributions determined by microscopy on collected cyclone samples indicate that cyclone cutoffs are very wide, and particularly for PM2.5, cyclone collections may greatly overestimate the total mass.


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