Decontamination of respirators amid shortages due to SARS-CoV-2

Abstract

The pandemic created by SARS-CoV-2 has caused a shortage in the supplies of N95 filtering facepiece respirators (FFRs), disposable respirators with at least 95% efficiency to remove non-oily airborne particles, due to increasing cases all over the world. The current article reviewed various possible decontamination methods for FFR reuse including ultraviolet germicidal irradiation (UVGI), hydrogen peroxide vapor (HPV), microwave-generated steam (MGS), hydrogen peroxide gas plasma (HPGP), and 70% or higher ethanol solution. HPV decontamination was effective against bacterial spores (6 log 10 reduction of Geobacillus stearothermophilus spores ) on FFRs and viruses (> 4 log 10 reduction of various types of viruses) on inanimate surfaces, and no degradation of respirator materials and fit has been reported. 70% or higher ethanol decontamination showed high efficacy in inactivation of coronaviruses on inanimate surfaces (> 3.9 log 10 reduction) but it was lower on FFRs which filtration efficiency was also decreased. UVGI method had good biocidal efficacy on FFRs (> 3 log 10 reduction of H1N1 virus) combined with inexpensive, readily available equipment; however, it was more time-consuming to ensure sufficient reduction in SARS-CoV-2. MGS treatment also provided good viral decontamination on FFRs (> 4 log 10 reduction of H1N1 virus) along with less time-intensive process and readily available equipment while inconsistent disinfection on the treated surfaces and deterioration of nose cushion of FFRs were observed. HPGP was a good virucidal system (> 6 log 10 reduction of Vesicular stomatitis virus ) but filtration efficiency after decontamination was inconsistent. Overall, HPV appeared to be one of the most promising methods based on the high biocidal efficacy on FFRs, preservation of respirator performance after multiple cycles, and no residual chemical toxicity. Nonetheless, equipment cost and time of the HPV process and a suitable operating room need to be considered.

Polarity‐Dominated Stable N97 Respirators for Airborne Virus Capture Based on Nanofibrous Membranes

“…To investigate the reusability of TFPNMs,five commonly home-exercisable methods were operated on cTFPNMs: [24] (1) heat treatment with temperature at 80 8 8C( High temperature above 70 8 8Cc ould lead to protein denaturation of SARS-CoV-2 over 5min); [25] (2) steam (100 8 8Ch eat-based protein denaturation);( 3) 75 %a lcohol (protein denaturation); [26] (4) domestic chlorine-based solution (cellular denaturation, with chemical damage); [27] (5) ultraviolet germicidal irradiation (DNA/RNAdisruption, UVC 254 nm). [28] As seen in Supporting Information, Table S4, all the filtration efficiencies remain unchanged at N97 level after the first treatment cycle with pressure drops maintained at 9-10 Pa. Theg eometry and loftiness of the cTFPNMs are unchanged (Supporting Information, Figure S7) and the surface polarities keep comparable (Supporting Information, Table S1), which further demonstrates that the TFPNMs are stable for reuse.I nc ontrast, the N95 FFRs show different filtration performances upon various treatments after the first cycle.As seen in Supporting Information, Table S5, heating and ultraviolet germicidal irradiation (UVGI) can preserve the filtration characteristics for most N95 FFRs.H owever,t he filtration efficiencies drastically decrease to 50-80 %u pon solu-tion-based treatments with ac omplete degradation on electrostatic charge quantity to 0kV, which is far beyond N95 grade.T aking the MEO-brand N95 FFR as an example, large pores randomly exist in the meltblown samples (Supporting Information, Figure S8), leading to an unacceptable filtration efficiencya t6 8.58 %a nd 57.33 %i n7 5% alcohol and chlorine-based solution, respectively.T he corresponding pressure drops change from 8Pat o1 0Pa( in 75 %a lcohol) and 5Pa( in chlorine-based solution), respectively (Supporting Information, Table S6).…”

Preparing for the Next Pandemic: Predicting UV Inactivation of Coronaviruses with Machine Learning

“…(3) data were directly or indirectly presented as virus residual titers after UV inactivation rather than reaction rate constants; (4) coronavirus sources, e.g., accession number of Genebank or Global Initiative of Sharing All Influenza Data (GISAID), or time and place of virus sampling should be provided; (5) information on virus propagation, e.g., culture medium types, additive, and duration, should be clear; (6) for coronaviruses in liquids, solutions should be culture medium, phosphate buffer solution (PBS), or other nonopaque liquids rather than plasma; for coronaviruses in air, air humidity and flow rate should be provided; for coronaviruses on surfaces, surface material and coronavirus condition (wet or dried) should be explicit. A more detailed explanation of these criteria is presented in Text S1, and the selected articles for data extraction are listed in Table S1.…”

“…2 To prevent infection by contaminated surroundings and inhibit viral transmission, UV irradiation has been widely applied in areas such as public transport, office spaces, and hospitals 3,4 and in particular for the decontamination of masks or respirators for reuse. 5,6 Therefore, it is critical to specify an effective UV dose for a given disinfection scenario to balance the cost of disinfection and the effectiveness of inactivation for coronaviruses. Previous studies have presented valuable contributions in predicting the rate constants of virus inactivation by UV irradiation.…”

“…After Severe Acute Respiratory Syndrome Coronavirus 1 (SARS-CoV-1) in 2003 with a 10% mortality rate and Middle East Respiratory Syndrome (MERS) in 2012 with a 35% mortality rate, SARS-CoV-2 has been unprecedentedly sweeping the world and causing millions of deaths and countless economic losses . To prevent infection by contaminated surroundings and inhibit viral transmission, UV irradiation has been widely applied in areas such as public transport, office spaces, and hospitals , and in particular for the decontamination of masks or respirators for reuse. , Therefore, it is critical to specify an effective UV dose for a given disinfection scenario to balance the cost of disinfection and the effectiveness of inactivation for coronaviruses. Previous studies have presented valuable contributions in predicting the rate constants of virus inactivation by UV irradiation.…”

Self‐reported Side‐effects ofUltraviolet‐CDisinfection Devices

“…The COVID‐19 pandemic has brought to the fore discussions regarding the effectiveness of UV‐C in inactivating viruses both via far‐UV‐C (1), which uses lower range wavelengths, and portable UV‐C devices. Specifically, there has been a rise in the sale of the latter for use in various settings (workplaces, homes, transport) and for purposes such as disinfecting the air, surfaces and objects (2‐7). However, the relative benefit of using portable UV‐C devices to reduce the risk of COVID‐19 transmission in individual settings, compared to other mitigation measures, is still unknown (8).…”