Comparative Performance of the NanoScan and the Classic SMPS in Determining N95 Filtering Facepiece Efficiency Against Nanoparticles

Nanoparticles are defined as particles with at least one dimension in the range of 1-100 nm. Due to the special properties of nanoparticles, they are used in many workplaces, thus leading to occupational exposure. Filtering facepieces (FFPs) are generally used in these workplaces to reduce the exposure. Many studies have measured FFP efficiency in laboratories using a scanning mobility particle sizer (SMPS). The aim of this study was to determine whether a NanoScan could be used to measure FFP efficiency against nanoparticles in workplaces for one type of N95 FFP. The results showed that the NanoScan gave maximum penetration and most penetrating particle size (MPPS) data for all configurations tested. Observations were consistent with those of previous studies: low penetration, MPPS smaller than 100 nm, and penetration increased as the airflow rate increased. The NanoScan gave a less precise MPPS and a slightly overestimated maximum penetration. These results confirm that the classic SMPS is a more precise instrument considering these two devices, whereas the NanoScan is faster to provide general information about the overall behaviour, which make it easy to use for a workplace environment. A NanoScan can thus be used as a first approach in workplaces.