Extending traceability in airborne particle size distribution measurements beyond 10 µm: Counting efficiency and unit-to-unit variability of four aerodynamic particle size spectrometers

• Published in: Aerosol science and technology Vol. 57; no. 1; pp. 24 - 34
• Main Authors: Vasilatou, Konstantina, Wälchli, Christian, Iida, Kenjiro, Horender, Stefan, Tritscher, Torsten, Hammer, Tobias, Rissler, Jenny, Gaie-Levrel, François, Auderset, Kevin
• Format: Journal Article
• Language: English
• Published: New York Taylor & Francis 2023; Taylor & Francis Ltd
• Subjects: Aerodynamic particles; Aerodynamics; Aerosols; Airborne particle; Airborne sensing; Atmospheric aerosols; Bioaerosols; Calibration; Counting efficiency; Data interpretation; Diameters; Earth and Related Environmental Sciences; Efficiency; Geovetenskap och miljövetenskap; Jason Olfert; Meteorologi och atmosfärforskning; Meteorology and Atmospheric Sciences; Natural Sciences; Naturvetenskap; Number concentration; Optical; Particle counters; Particle size; Particle size analysis; Particle size distribution; Particle size distribution measurement; Particles sizes; Polystyrene resins; Primary standards; Radiation counters; Spectrometers; Switzerland; Switzerland
• ISSN: 0278-6826; 1521-7388; 1521-7388
• DOI: 10.1080/02786826.2022.2139659

The aim of this study was to establish traceable number concentration measurements of airborne particles beyond 10 μm in particle size. To this end, the primary standards for particle number concentration at the National Metrology Institutes of Switzerland and Japan were further developed to extend their measurement capabilities. Details on the upgraded setup are provided. An inter-comparison of the two primary standards using an optical particle counter as transfer standard showed that these agree well within the stated uncertainties at polystyrene (PS) equivalent optical diameter of 15 µm. Subsequently, four Model 3321 (TSI Inc., USA) aerodynamic particle size spectrometers (APS) were calibrated against the primary standard of Switzerland using size-certified PS spheres with optical/aerodynamic diameter up to 20 µm as test aerosols. The counting efficiency profile and unit-to-unit variability of the APS units were determined. The results presented here can be useful for the analysis and interpretation of data collected by the different atmospheric aerosol networks worldwide. The outlined methodology can also be applied in the calibration of automated bio-aerosol monitors.