Microwave- and Heat-Based Decontamination of N95 Filtering Facepiece Respirators: A Systematic Review

Abstract

Background: In pandemic situations such as COVID-19, shortages of proper protective equipment are common. One solution may be to decontaminate equipment such as facemasks for reuse.Aim: The aim of this review was 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) and fit.Methods: A systematic review (PROSPERO ID pending) of literature available on Medline, Embase, Global Health, JISRP and JEFF was conducted. Records were screened independently by two reviewers, and data was extracted and analyzed from studies that reported on the effects of microwave- or heat-based decontamination on N95 FFR performance and/or microbial load. Results: All interventions successfully destroyed viral/bacterial contaminants. Other than autoclaving, which significantly increased aerosol penetration, moist and dry microwave and heat conditions did not significantly impact functional parameters or fit. However, several conditions caused physical damage to at least one N95 model. Conclusions: Microwave irradiation and heat provides safe and effective decontamination options for N95 FFR reuse during critical shortages. However, autoclaving masks is not recommended by the evidence in this review. Any mask disinfected using these methods should be inspected for physical degradation before reuse.NOTE: The experiments summarized in this manuscript are performed under specialized laboratory conditions. Household appliances should not be used for any purposes that are not indicated in their manufacturer-supplied guidelines, including mask decontamination. Doing so may lead to damage or injury.

Heat-treated virus inactivation rate depends strongly on treatment procedure: illustration with SARS-CoV-2

“…In addition, the impact of procedure is likely to differ across microbes, in particular when considering enveloped versus non-enveloped viruses, or viruses versus bacteria [ 30 ]. Finally, another critical aspect to consider is the potential impact on the integrity of the decontaminated equipment or specimen, notably for PPE and biological samples [ 11 , 35 , 36 ]. Any effort to translate inactivation rates (or even relative patterns) from one setting to another should thus be undertaken cautiously, accounting for these factors.…”

Increased plastic pollution due to COVID-19 pandemic: Challenges and recommendations

“…combination of materials as composites) [87]. The use of UV-C light, ozone gas, ionised hydrogen peroxide, and microwave-and heat-based seem to be valid decontamination approaches to apply to PPE and N95 masks, improving their reusability and reducing the production of waste [82][83][84][85][86]88,89].…”

“…Therefore, municipalities responsible for waste collection and treatment should create guidelines and procedures to apply during pandemics regarding waste reduction recommendations, protective measures, collection frequency, and end-of-life.ii) Disinfection of medical wastes and PPE allowing for safe recyclingDuring pandemic events, all medical waste and PPE should be carefully monitored by specialised personnel to guarantee health safety. Disinfection technology, including UV, ozone or bioengineering approaches, can offer a sustainable strategy to treat waste and wastewaters[82][83][84][85][86]. The choice of an appropriate disinfection technology should rely on the amount of waste, type of waste, costs and maintenance.…”

“…For high volumes of infectious medical waste (> 10 t/d) the incineration continues to be the best option as it completely kills pathogens due to the high-temperature applied (over 800ºC). If the amount of medical waste is not too high (< 10 t/d), chemical disinfection (i.e., use of chemical disinfectants) or physical disinfection (microwave or high temperature steam) might be an option[84].…”

Efficacy and safety of disinfectants for decontamination of N95 and SN95 filtering facepiece respirators: a systematic review

“…To help inform FFR-reuse policies and procedures, our team has conducted three systematic reviews to synthesize existing published data regarding the effectiveness of UVGI[ 24 ], heat and microwave irradiation[ 25 ], and chemical disinfectants for decontamination of National Institute for Occupational Safety and Health (NIOSH)-approved N95 FFRs. This review will focus on chemical disinfectants, with the following objectives: (1) to assess the impact of the each disinfectant method on FFR performance, with a specific focus on aerosol penetration and airflow resistance; (2) to determine the effectiveness of each disinfectant method at reducing viral or bacterial load; (3) to describe observations related to changes in physical traits following decontamination with a disinfectant; (4) to determine the impact of each disinfectant on FFR fit; and (5) to describe findings or observations related to potential health risks or irritation from residual disinfectant remaining on FFRs following decontamination.…”