key: cord-0936676-fn3oeiov
authors: Alt, Jodi; Eveland, Randal; Fiorello, Anthony; Haas, Bruno; Meszaros, Janet; McEvoy, Brian; Ridenour, Callie; Shaffer, Diana; Yirava, William; Ward, Lisa
title: Development and validation of technologies suitable for the decontamination and re-use of contaminated N95 filtering facepiece respirators in response to the COVID-19 pandemic.
date: 2021-10-09
journal: J Hosp Infect
DOI: 10.1016/j.jhin.2021.10.004
sha: 6674d0feab3130d6d7f88bf74169a19aa02a0bcb
doc_id: 936676
cord_uid: fn3oeiov

BACKGROUND: COVID-19 has brought significant challenges to society globally, particularly in the area of healthcare provision. A pressing need exists in protecting those tasked with delivering healthcare solutions during the COVID-19 crisis by providing solutions for preserving adequate supplies of effective personal protective equipment (PPE). AIM: To evaluate and validate available methods for the decontamination of N95 filtering facepiece respirators (FFRs) while maintaining functionality during re-use. METHODS: Multiple low temperature steam and vaporized hydrogen peroxide (VHP) technologies were assessed for inactivation of Mycobacterium sp. and Feline calicivirus (employed as representatives of the contamination challenge). FINDINGS: Virus (≥ 3log(10)) and Mycobacterium sp. (≥ 6log(10)) inactivation on varying types of N95 FFRs using an array of heat (65-71(o)C), humidity (>50% RH) and VHP without affecting the performance of the PPE. CONCLUSION: Methods have been validated and were authorized by the United States Food and Drug Administration (US FDA) under a temporary Emergency Use Authorization (EUA). Based on findings, opportunities exist for development and deployment of decontamination methods made from simple, general-purpose materials and equipment should a future need arise.

Background: COVID-19 has brought significant challenges to society globally, particularly in 23 the area of healthcare provision. A pressing need exists in protecting those tasked with 24 delivering healthcare solutions during the COVID-19 crisis by providing solutions for 25 preserving adequate supplies of effective personal protective equipment (PPE). (ii) re-use or (iii) using alternative PPE [5] . To address known shortages of N95 availability in 75 the US, the Center for Disease Control and Prevention published recommendations for 76 extended use or limited re-use as potential mitigation strategies [9] . Decontamination has 77 been proposed as another strategy to further extend the re-use of masks. shortcomings. For example, simple cleaning strategies using both inert and disinfection 86 wipes are effective in decontamination but can damage key attributes of FFRs, such as the 87 filtering effect on electrostatic polypropylene [10, 11] . 88 89 With the onset of FFR shortages during COVID-19, a diverse range of decontamination 90

technologies have been explored with many showing to be successful in address the need of 91 providing safe FFR following the application of the decontamination method [12, 13, 14] . 92

The aim of this study was to (i) assess potential candidate technologies for decontaminating 94 compatible FFRs, (ii) validate the selected technologies with approved methods (iii) 95 demonstrate that the PPE remains fully functional. An additional aim of this study is to 96 demonstrate methods that may be of consideration where sterilization equipment 97 resources are limited. While the purpose of the research is applicable to the current 98 challenges of COVID-19, future considerations may pertain to the environmental impacts of 99 PPE and long-term sustainability [12] . It is estimated that some 44 million nonwoven PPE 100 items are utilized by front-line workers every day, resulting in some 15,000 tonnes of waste 101 [12] . While many materials in PPE are recyclable, contamination significantly influences 102 disposal strategies, and this is coupled with the natural resource consumption during 103 manufacture, which collectively may be environmentally impacting [15, 16] . vaporized hydrogen peroxide (VHP) and moist heat were considered based on effectiveness, 111 availability, and safety. Radiation sterilization and heat processes above 75 o C were 112 eliminated due to material incompatibility and EO was omitted due to potential residues. 113 All other candidate technologies described in Table I 

The processes were challenged with appropriate soil challenges comprised of mucin and 131 saline based upon guidance from ASTM standard E2721-16 [18] . Cells were incubated at 37⁰C, 5% CO2, at ≥85% RH for up to 7 days and monitored 209 periodically for viral cytopathic effect (CPE) using an inverted microscope. 210

The recovery media of coupons left uninoculated and without exposure to decontamination 211 was used to evaluate mask material cytotoxicity to the cell line associated with virus testing. 212

Testing of all mask models demonstrated no detectable levels of cytotoxicity to CRFK cells. 

Microbiological Inactivation 288 289

Results of microbiological inactivation of various FFR's using a number of decontamination 290 technologies are described in Table II humidity. The benefit of humidity was observed where trials performed at the defined 310 temperatures (using 3M 8210 and 3M 1860 mask types) without humidity yielded 311 inactivation typically less than the desired 3 log10 minimum. Therefore, in order to surpass 312 the 3 log10 minimum target, RH of 40% or more was established as a process parameter. 313

Washer-disinfector was only tested with Mycobacterium and was shown to provide ≥ 6 log10 314 inactivation. 315

The mask fibre material and the exhalation valve of the 3M 8511 N95 FFR were evaluated 317 separately for decontamination. The resulting log10 reductions of each were coalesced to 318 demonstrate the effects of decontamination of the overall mask. In Table II resulted in all respirators meet the acceptance criteria for newly produced respirators 330 (Table III) processes. Material evaluations of unprocessed versus 10x or 20x exposed masks showed 345 no significant differences between unprocessed and exposed masks. While the plastic masks 346 have excellent compatibility, masks constructed with cellulose or cellulose materials were 347 appropriately excluded from decontamination with VHP due to known incompatibility issues 348 between hydrogen peroxide and cellulosic materials. 

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Decontamination Procedures for Surfaces When Challenged with Droplets Containing 536 Human Pathogenic Viruses

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A pandemic 544 influenza preparedness study: Use of energetic methods to decontaminate filtering 545 facepiece respirators contaminated with H1N1 aerosols and droplets

Development of a test system to 548 apply virus-containing particles to filtering facepiece respirators for the evaluation of 549 decontamination procedures

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The authors acknowledge the support and advice of 3M regarding the Physical Performance 461 testing performed on the N95 FFR. 462The authors also acknowledge all the STERIS personnel who have provided support to this 463 research. 464 465

All authors employed by STERIS. 467