The Influence Factors of Mean Particle Size and Positive Control of Bacterial Filtration Efficiency System

Author(s): Yayi Yi, Dianlong Shi, Chunlei He, Kai Liu, Qiangqiang He

The Coronavirus Disease 2019 (COVID-19) has swept the whole world with high mortality. Since aerosol transmission is the main route of transmission, wearing a mask serves as a crucial preventive measure. An important parameter to evaluate the performance of a mask is the bacteria filtration efficiency (BFE). Aerosol mean particle size (MPS) and positive control value (PCV) are two key indexes of BFE system. In this study, we investigated the influence of Andersen sampler, spray flow, medium thickness, and peristaltic pump flow on MPS of bacterial aerosols and PCV of BFE system, respectively. The results show that the machining accuracy of Andersen sampler has great influence on aerosol MPS and PCV. With the increase of aerosol spray flow rate, the PCV will increase gradually, but the effect on MPS is not a simple linear relationship. As the agar medium thickness increased, the PCV and MPS increased gradually. With the increase of peristaltic pump flow, the PCV increased gradually, while the MPS was basically in a downward trend. When the peristatic pump flow rate was 0.1mL/min, the spray flow rate was 7.2L/min, the agar plate thickness was 27mL, and the Andersen sampler of Beijing Mingjie was used for the experiment, the aerosol MPS and PCV were both within the acceptable range and were the optimal parameters. This study provides guidance for the manufacturers of the BFE system and improves the protective performance of masks, which is important for the human health, especially during the occurrence of viral pandemics such as "COVID-19".