The effect of hypochlorous acid on the filtration performance and bacterial decontamination of N95 filtering facemask respirators

Background: Stabilized hypochlorous acid (HOCl) is increasingly used as a hospital disinfectant and antisep-tic, yet its effect on N95 filtration facemask respirators (FFR) is unknown. These FFRs could also contribute to fomite-based transmission of nosocomial infections if worn for extended use between patient rooms.Methods: Filtration performance of N95 FFR fabric swatches was assessed after various levels of HOCl expo-sure. N95 swatches were then contaminated with 108 Escherichia coli or 108 Staphylococci aureus and treated with HOCl solution, 70% ethyl alcohol, or normal saline. Surviving bacterial numbers were assessed by plate counts.Results: The size-dependent filtration efficiency of HOCl-sprayed N95 FFR fabric ranged from 96% to 100%, showing no significant change. Flow resistance testing revealed almost no change compared to control. Sub-mersion in HOCl, but not spraying, had an excellent bactericidal effect on contaminated swatches.Discussion: The role of the outer hydrophobic layer of N95 FFRs is discussed regarding the effects of HOCl on filtration and bacterial decontamination.Conclusions: N95 material, sprayed with or briefly submerged in HOCl, maintained its filtration function. HOCl delivery by spray pump, however, would not accomplish decontamination of extended use FFRs between patient encounters. HOCl submersion of intact FFRs, contaminated with various hospital pathogens, is worth further study.(c) 2022 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.