Microwave- and heat-based decontamination of N95 filtering facepiece respirators: a systematic review

Abstract

Background In pandemics such as COVID-19, shortages of personal protective equipment are common. One solution may be to decontaminate equipment such as facemasks for reuse. Aim To collect and synthesize existing information on decontamination of N95 filtering facepiece respirators (FFRs) using microwave and heat-based treatments, with special attention to impact on mask function (aerosol penetration, airflow resistance), fit, and physical traits. Methods A systematic review (PROSPERO CRD42020177036) of literature available from Medline, Embase, Global Health, and other sources was conducted. Records were screened independently by two reviewers, and data was extracted from studies that reported on effects of microwave- or heat-based decontamination on N95 FFR performance, fit, physical traits, and/or reductions in microbial load. Findings Thirteen studies were included that used dry/moist microwave irradiation, heat, or autoclaving. All treatment types reduced pathogen load by a log10 reduction factor of at least three when applied for sufficient duration (>30s microwave, >60 min dry heat), with most studies assessing viral pathogens. Mask function (aerosol penetration <5% and airflow resistance <25mmH 2 O) was preserved after all treatments except autoclaving. Fit was maintained for most N95 models, though all treatment types caused observable physical damage to at least one model. Conclusions Microwave irradiation and heat may be safe and effective viral decontamination options for N95 FFR reuse during critical shortages. The evidence does not support autoclaving or high-heat (>90 o C) approaches. Physical degradation may be an issue for certain mask models, and more real-world evidence on fit is needed.

Mask decontamination methods (model N95) for respiratory protection: a rapid review

“…A previous systematic review that included 15 studies concluded that future studies are required in order to establish the e cacy and security the e cacy and safety of N95 decontamination methods. 18 Others systematic reviews have reported that masks can be decontaminated with microwave irradiation and moderate-temperature heat (up to 90°C), in both moist and dry conditions 19 and a single cycle of vaporized H 2 O 2 can be used as chemical disinfectant to remove viral pathogens without degrading the masks. 21 However there is not su cient evidence concerning UVGI as a safe decontamination method.…”

“…Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the coronavirus pandemic (COVID- 19), has affected the world and changed the way we live. [1][2][3][4][5] Aerosols, droplets, secretions, and direct contact with nasal mucosa are the main respiratory transmission routes of these viruses between humans.…”

“…A recent systematic review evaluated the e cacy and safety of N95 mask decontamination methods from SARS-CoV-2. 18 Other reviews were carried out evaluating speci c methods of decontamination, such as microwave and heat 19 , ultraviolet germicidal irradiation 20 and chemical disinfectants. 21 Concerns about e cacy and safety of methods of decontamination of personal protective equipment is, and will continue to be, relevant for scienti c evidence as there has been likelihood for a second wave of COVID-19 recently.…”

Extended use or reuse of single-use surgical masks and filtering face-piece respirators during the coronavirus disease 2019 (COVID-19) pandemic: A rapid systematic review

“…All were conducted in Canada; 3 were conducted by the same research team. These 3 focused on reprocessing of filtering face-piece respirators using different decontamination interventions (ie, heat-based treatments, disinfectant, and ultraviolet germicidal irradiation), [17][18][19] and 1 study covered reprocessing of surgical masks and 'precontamination' interventions applied before use to enable extended use or reuse. No reviews in our sample examined the impact of extended use or reuse of filtering facepiece respirators or surgical masks on the ability to meet technical standards or on healthcare worker acceptability outcomes such as comfort.…”

Evaluating the relationship between citation set size, team size and screening methods used in systematic reviews: a cross-sectional study

“…This would reduce the workload per reviewer, facilitating faster and potentially more valid and reliable work [ 18 , 19 ]. For example, our team of almost twenty reviewers completed four systematic reviews on mask decontamination during the COVID-19 pandemic, in an average time of two weeks from protocol development to manuscript dissemination on the Open Science Framework [ 20 – 23 ]. This large team or crowdsourcing approach can be helpful when SRs involve many tasks (e.g.…”