Using a DiSCmini classifier for real-time determination of ultrafine particle mass concentrationapplication to diesel particle measurement

Exposure to ultrafine particles (particle diameter <100nm) in workplace atmospheres requires direct-reading measuring instruments. The DiSCmini (Testo((R))) is a portable device designed for the real-time measurement of particle number concentration and average diameter. However, exposure to airborne particles is traditionally expressed in terms of mass concentration; this knowledge of mass also allows comparison with other measurement methods as well as occupational exposure limits. In this study, the mass concentration was determined from the two parameters measured by the DiSCmini, i.e., the number concentration and the average diameter. The calculation of the mass concentration was made possible by taking into account particle number size distribution and effective density. Different approaches were considered to simplify the calculations as much as possible. These approaches were tested in the laboratory with combustion test aerosols generated from a diesel engine.