Qualitative Knowledge of Filtering Facepiece Respirators for Filtration Performance Tests during the COVID-19 Pandemic
C. Brochot, M. N. Saidi, and A. Bahloul
Background: During the COVID-19 pandemic, the pressure on health centers to obtain certified N95 filtering facepiece respirators (N95 FFRs) and the pressure on the FFRs production sector led to a diversification of FFRs’ supply chains, with the approval of several government authorities.
Objective: The main issue then becomes whether these purchased FFRs are as effective as the FFRs commonly used in the pre-COVID-19 period.
Methods: The most efficient way is to test these FFRs under normative conditions. The setup used here allows to measure the pressure drop Δp (mbar) and the filtration efficiency E (%) of FFRs with a constant 85 Liter per minute. However, it would be useful to find visible markers that could indicate a possible defect (intentional or not) or a possible counterfeit.
Results and conclusions: The performance measurements and visual inspections of 43 types of FFRs are compared and analyzed in this paper. 35% of the FFRs received in the laboratory have a minimum filtration efficiency greater than 95%, and 28% have a minimum efficiency less than 80%. The results show that marks on FFRs are not a clear and precise indicator of the efficiency of the FFR. However, a visual inspection and a preliminary fit test can identify some ineffective FFRs.
Keywords: COVID-19, filtering facepiece respirator, filtration performance, aerosol, visual inspection, respirator certification.