Is it possible to decontaminate N95 masks in pandemic times? integrative literature review

Oliveira, Adriana Cristina de; Lucas, Thabata Coaglio

doi:10.1590/1983-1447.2021.20200146

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Integrative Review • Rev. Gaúcha Enferm. 42 (spe) • 2021 • https://doi.org/10.1590/1983-1447.2021.20200146 linkcopy

Is it possible to decontaminate N95 masks in pandemic times? integrative literature review

¿Es posible descontaminar las máscaras N95 en tiempos pandémicos? revisión integrativa de la literatura

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Objective: To evaluate the protocols on decontamination/reuse of N95 masks available in the literature in times of the Covid-19 pandemic.

Method: Integrative literature review, in the period from 2010 to 2020, on the databases MEDLINE/PubMed, Science Direct, Cochrane, SAGE journals, Web of Science, Scopus, Embase and Wiley, with the descriptors Masks AND Respiratory protective devices; Mask OR N95 AND Covid-19; N95 AND Respirators; Decontamination AND N95 AND Coronavirus; Facemask OR Pandemic.

Results: Twelve studies were included, of which 3 (30.0%) used ultraviolet germicidal irradiation and indicated mask deterioration between 2 and 10 cycles, 4 (40.0%) used hydrogen peroxide vapor, and seal loss varied from 5 to 20 cycles, 4 (33.3%) evaluated the structural integrity of the N95 mask through visual inspection and 6 (54.4%), its filtration efficiency.

Conclusion: Reuse strategies to overcome a shortage of devices in the face of the pandemic challenge the current concept for good practices in health-product processing.

Keywords:
Masks; Respiratory protective devices; Decontamination; Coronavirus; Coronavirus infections; Pandemics

Author/year	Study design	Decontamination methods	Results
Lindsley et al.¹⁵ 2015	Experimental study: - Particle penetration test. Flow resistance test. -Respirator tissue layer traction test. -Elastic strap stretch test.	Ultraviolet germicidal irradiation. Number of cycles tested: five cycles.	-90% of the material degraded after the second cycle in doses of 120-470 joules per square centimeter. -Braking force decreased and varied between models: up to 90%. -Resistance to flow increased. -Small increase (up to 1.25%) in particle penetration.
Battelle¹⁶ 2016	Experimental study: -Aerosol filtration performance tests. -Inhalation resistance test. -N95 mask sealing test. -Visual and tactile Integrity test.	Hydrogen peroxide vapor. Number of cycles tested: fifty cycles.	-Visual inspection. Fragmentation of the elastic strips after thirty cycles. -Sealing test - endured twenty cycles. -Efficiency of aerosol filtration and inhalation resistance endured fifty cycles.
Lin et al.¹⁷ 2017	Experimental study: - Particle penetration test. - Filtration test.	Dry heat, moist hear autoclave, low temperature decontamination using ethanol, isopropanol and bleach. Number of cycles tested: six cycles.	-Particle penetration greater than 27.9 nanometers increased by 5% and, for particles from 14.1 to 594 nanometers, increased by 8.6% after six cycles. -Liquid chemical methods destroyed the N95 mask filter after six cycles; -The N95 mask filter has melted in dry heat with temperatures higher than 100 ⁰C.
Mills et al.¹⁸ 2018	Experimental study: -Test evaluated the decreased logarithmic concentration of the virus (10⁵ viruses by filtering the face mask).	Germicidal ultraviolet irradiation. Number of cycles tested: one cycle.	-Reduction of viral load in 12 models of masks after dose of one joule per square centimeter. -Three models did not present significant decrease in the viral load tested.
Kenney et al.¹⁹ 2020	Experimental Study: -Contamination of N95 masks by aerolized virus. -Visual and tactile Integrity test.	Hydrogen peroxide vapor. Number of cycles tested: five cycles.	-Visual inspection did not reveal any visible deformities. -Reduction of infectious virus load below the detection limit (reduced about 10% of the infectious dose applied in tissue culture).
Price and Chu ¹² 2020	Experimental study: Contamination of N95 masks with Escherichia coli.	Dry heat. Number of cycles tested: twenty cycles.	-Maintenance of filtration performance in up to twenty cycles. -The method was efficient in decreasing 99% of Escherichia Coli.
Oral et al.²⁰ 2020	Experimental study: -Filtration test. -Sealing test. -Contamination of N95 masks by SARS-Cov-2 (National Emerging Infectious Diseases Laboratories/Level 4).	Hydrogen peroxide vapor. Number of cycles tested: one cycle.	-Filtration and sealing not compromised. -Reduction of the infectious virus load to below the detection limit.
Liao et al.²¹ 2020	Experimental study: - Filtration test.	Germicidal ultraviolet irradiation. Number of cycles tested: ten cycles. Ethanol and 2% chlorine-based solution. Number of cycles tested: one cycle. Dry heat. Number of cycles tested: twenty cycles.	-Ultraviolet irradiation by germicide: filtration efficiency has not been compromised. Signs of deterioration after ten cycles. -Ethanol and 2% chlorine-based solution: filtration degradation and impairment. -Dry heat: efficiency greater than 95% in filtration.
Kumar et al.²² 2020	Experimental study: -External contamination of the mask with the vesicular stomatitis virus or with Sars-CoV-2 (National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Canada). -Sealing test.	Hydrogen peroxide vapor. Number of cycles tested: ten cycles. Steam autoclave. Number of cycles tested: ten cycles. Ethylene oxide. Number of cycles tested: three cycles.	-Hydrogen peroxide vapor: loss of the functionality of the N95 mask in five cycles. There was no recovery of viral load after ten cycles. -Steam autoclave: loss of N95 mask adjustment in the first cycle. -Ethylene oxide: maintenance of the N95 mask adjustment in the three cycles. There was no recovery of viral load after ten cycles.
Pascoe et al.²³ 2020	Experimental study: -Contamination of N95 masks with Staphylococcus aureus. -Filtration test. -Visual and tactile integrity.	Dry heat and steam generated by a microwave oven. Number of cycles tested: three cycles.	-Dry heat and steam generated by a microwave oven: the methods were efficient in decreasing 99% of Staphylococcus aureus ; -Dry heat and steam generated by microwave oven: loss of 50% in filtration efficiency. -Vapor generated by a microwave oven: loss of the integrity of the N95 mask after a cycle (deterioration of the metal clip and presence of holes), The elastic straps were not compromised.
Xiang et al. ²⁴ 2020	Experimental study: -Contamination of N95 masks with six strains of pathogenic bacteria, one of fungus and one of the H1N1 virus. -Filtration test. -Sealing test.	Dry heat. Number of cycles tested: one cycle.	-Elimination of strains and inactivation of the H1N1 virus. -Efficiency greater than 95% in filtration. -Maintenance of the N95 mask adjustment.

Decontamination method	Results after three tested cycles
Hydrogen peroxide gas plasma (STERRAD^®100S); Specifications. 59% hydrogen peroxide, short cycle for 55 minutes, temperature between 45 ⁰C and 55 ⁰C.	-Increased particle penetration level in more than 5%. -Little or no effect on filtration efficiency. -No changes in the physical integrity of the N95 mask were observed.
Hydrogen peroxide vapor (RBDS™, BIOQUELL UK Ltd, Andover, UK). Specifications 30% hydrogen peroxide. 15 minutes of stay and 125 minutes for the total cycle. Aeration for 24 hours.	-Little or no effect on filtration efficiency. -No changes in the physical integrity of the N95 mask were observed.
Germicidal ultraviolet irradiation (UV Bench Lamp (UV-C, 254 nanometers, 40 W), Model XX-40S (UVP, LLC, Upland, CA). Specifications 45 minutes of exposure to an intensity of 1.8 microwatt per square centimeter. Only the outside of the mask was exposed.	-Little or no effect on filtration efficiency. -Increased particle penetration for particles smaller than 2.12%; -No changes in the physical integrity of the N95 mask were observed.
Ethylene oxide. Amsco^® Eagle^® 3017, 100% ethylene oxide, Sterilizer/Aerator (STERIS Corporation , Mentor, OH); Specifications: one hour of exposure (736 milligrams per liter), followed by 12 hours of aeration.	-Increased particle penetration for particles smaller than 2.12%; -No changes were observed in the physical integrity of the N95 mask. -Little or no effect on filtration efficiency.
Liquid hydrogen peroxide. Specifications 30% hydrogen peroxide. 30 minutes of immersion in 6% hydrogen peroxide solution.	-Oxidation of the clamps in varying degrees.
Wet heating. (80% relative humidity in a Caron 6010^® laboratory incubator model (Marietta, OH)). Specifications: 30 minutes incubation at 60⁰ C.	-Separation of the N95 mask foam. -Melting of elastic straps.
Bleach. Specifications. 30 minutes of submersion in 0.6% sodium hypochlorite solution.	-Slightly stained nasal foam. -Clamps with oxidation of several levels. -Inner nasal cushion discolored or dissolved.
Steam generated by microwaves; (2,450-Megahertz, model R-305KS ( Sharp Electronics Corporation, Mahwah, NJ). Specifications: exposure time of two minutes, at 10 Watts, with 1100 Watts being the maximum power of the equipment.	-Separation of the nasal foam. -Melting of elastic straps.

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Universidade Federal do Rio Grande do Sul. Escola de Enfermagem Rua São Manoel, 963 -Campus da Saúde , 90.620-110 - Porto Alegre - RS - Brasil, Fone: (55 51) 3308-5242 / Fax: (55 51) 3308-5436 - Porto Alegre - RS - Brazil
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[TFN1] Source: Research data, 2020.