An intercomparison study of optical particle size spectrometers for aerosol number size distribution measurements

An inter-laboratory comparison (ILC) involving optical particle size spectrometers (OPSSs) was organised at the French national level. The aim of this study was to make an inventory of the metrological capabilities of particle number size distribution (PNSD) measurements using OPSSs. This laboratory study was conducted over an 18-month period and involved 16 partners and 35 OPSSs. This large number of instruments provides strong statistical weight to the dataset, offering robust insight into the overall instrumental capabilities of accurately and reliably measuring PNSD. For that, each partner applied the same pre-defined experimental protocol to the OPSS(s) to be tested, operated together with a common control OPSS. Three different test aerosols were involved, and their PNSDs were measured: (1) a monodisperse amorphous silica sample, (2) glass beads, and (3) a green cornstarch powder. This article presents the measured PNSD using the 35 OPSSs associated with the description of the experimental set-up, sample preparation protocol, and comparison with scanning electron microscopy measurements.