Screen-printing of chitosan and cationised cellulose nanofibril coatings for integration into functional face masks with potential antiviral activity.

Masks proved to be necessary protective measure during the COVID-19 pandemic, but they provided a physical barrier rather than inactivating viruses, increasing the risk of cross-infection. In this study, high-molecular weight chitosan and cationised cellulose nanofibrils were screen-printed individually or as a mixture onto the inner surface of the first polypropylene (PP) layer. First, biopolymers were evaluated by various physicochemical methods for their suitability for screen-printing and antiviral activity. Second, the effect of the coatings was evaluated by analysing the morphology, surface chemistry, charge of the modified PP layer, air permeability, water-vapour retention, add-on, contact angle, antiviral activity against the model virus phi6 and cytotoxicity. Finally, the functional PP layers were integrated into face masks, and resulting masks were tested for wettability, air permeability, and viral filtration efficiency (VFE). Air permeability was reduced for modified PP layers (43 % reduction for kat-CNF) and face masks (52 % reduction of kat-CNF layer). The antiviral potential of the modified PP layers against phi6 showed inhibition of 0.08 to 0.97 log (pH 7.5) and cytotoxicity assay showed cell viability above 70 %. VFE of the masks remained the same (~99.9 %), even after applying the biopolymers, confirming that these masks provided high level of protection against viruses.

Effectiveness of a Low-cost UVGI Chamber for Decontaminating Filtering Facepiece Respirators to Extend Reuse.

In emergencies like the COVID-19 pandemic, reuse or reprocessing of filtering facepiece respirators (FFRs) may be required to mitigate exposure risk. Research gap: Only a few studies evaluated decontamination effectiveness against SARS-CoV-2 that are practical for low-resource settings. This study aimed to determine the effectiveness of a relatively inexpensive ultraviolet germicidal irradiation chamber to decontaminate FFRs contaminated with SARS-CoV-2. A custom design UVGI chamber was constructed to determine the ability to decontaminate seven FFR models including N95s, KN95 and FFP2s inoculated with SARS-CoV-2. Vflex was excluded due to design folds/pleats and UVGI shadowing inside the chamber. Structural and functional integrity tolerated by each FFR model on repeated decontamination cycles was assessed. Twenty-seven participants were fit tested over 30 cycles for each model and passed if the fit factor was ≥100. Of the FFR models included for testing, only the KN95 model failed filtration. The 3M™ 3M 1860 and Halyard™ duckbill 46727 (formerly Kimberly Clark) models performed better on fit testing than other models for both pre-and-post decontaminations. Fewer participants (0.3 and 0.7%, respectively) passed fit testing for Makrite 9500 N95 and Greenline 5200 FFP2 and only two for the KN95 model post decontamination. Fit testing appeared to be more affected by donning & doffing, as some passed with adjustment and repeat fit testing. A ≥ 3 log reduction of SARS-CoV-2 was achieved for worn-in FFRs namely Greenline 5200 FFP2. Conclusion: The study showed that not all FFRs tested could withstand 30 cycles of UVGI decontamination without diminishing filtration efficiency or facial fit. In addition, SARS-CoV-2 log reduction varied across the FFRs, implying that the decontamination efficacy largely depends on the decontamination protocol and selection of FFRs. We demonstrated the effectiveness of a low-cost and scalable decontamination method for SARS-CoV-2 and the effect on fit testing using people instead of manikins. It is recognised that extensive experimental evidence for the reuse of decontaminated FFRs is lacking, and thus this study would be relevant and of interest in crisis-capacity settings, particularly in low-resource facilities.

Face masks and respirators in the fight against the COVID-19 pandemic: An overview of the standards and testing methods.

The COVID-19 outbreak has resulted in a shortage of personal protective equipment (PPE) throughout the world. This shortage has resulted in an increase in production of PPE to meet the demand, and as a result, several substandard equipment has entered the market. With face masks and respirators now beginning to see widespread use throughout the world, the standards and test with which they are required to undertake have become points of interest. The filtration efficiency of the masks is a key testing element that examines its ability to filter particles, bacteria and viruses; this examines the penetration efficiency percentage of each with lower results being preferable. Masks are also subjected to NaCl testing method, which allows a range of particle sizes to be examined and their penetration to be observed. The masks must also show considerable resistance to fluids and flames, to prevent the penetration of liquids and to be non-flammable. Various PPE testing protocols such as biological, chemical, fluid and flame resistances, protective ensemble, facepiece fit testing, NIOSH NaCl method and impact protection have been discussed. In addition, various tests involving bacterial and viral filtration efficiencies are also discussed. Differential pressure is examined to ascertain the comfort, airflow and breathability of the masks, whilst fit testing is examined to ensure a correct fit of the mask.