Factors affecting decontamination of N95 masks for reuse: Feasibility & practicality of various methods

The SARS-CoV-2 pandemic has led to an enormous increase in cases worldwide in a short time. The potential shortage might call for the reuse of personal protective equipment especially N95 masks. In this review, the methods available for decontamination of N95 masks have been compared to highlight the advantages and efficacies of different methods. Studies conducted to evaluate the biocidal efficacy, effect on filtration efficacy of the decontamination method, and maintenance of structural integrity of masks, were reviewed. Ultraviolet germicidal irradiation (UVGI) and hydrogen peroxide (H₂O₂) vapour were the most commonly evaluated interventions and showed good germicidal activity without significant deleterious effects on mask performance. Vapourous H₂O₂ was the best method as it maintained NIOSH (The National Institute for Occupational Safety and Health) recommendations of the mask on re-use and additionally, one mask could be decontaminated and reused 30 times. Ethylene oxide (EtO) preserved the maximum filtration efficacy and flow resistance. Chemical and heat-based methods had the advantages of being cost-effective and feasible but affected the structural integrity and fit of the masks. For the decontamination of N95 masks, among the heat-based methods steam was found to be the best for low middle-income countries setting. H₂O₂-based methods, UVGI, and EtO all exhibited both adequate biocidal efficacies and functionality (fit testing and structural integrity). Further studies on logistics, healthcare worker acceptability of reuse, and actual efficacy of protection against SARS-CoV-2 infection should be carried out to validate the use of decontamination in the real-life settings.