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

Successful establishment and evaluation of a reprocessing concept via steam at 105 °C for FFP masks in hospitals in case of logistic shortages

Filtering face piece (FFP) masks according to EN 149 Respiratory protective devices - Filtering half masks to protect against particles - Requirements, testing, marking are essential components of personal protective equipment against biological agents from an occupational health and hospital hygiene perspective. Therefore, shortages due to increased demand or supply bottlenecks can lead to staff threats due to the risk of infection. To determine whether FFP masks could be made reusable in a hospital setting, a thermal reprocessing concept (steam at 105 °C with a holding phase of 10 min) was evaluated in a bed reprocessing chamber. The results indicate that it is logistically possible to establish a reprocessing concept. Of 267 reprocessed masks, 48 were rejected by inspection because of defect strapping, trapped hair, misfolding, and missing lot number or deformation, and 22 masks were rejected by bacteriological examination because of contamination > 10 CFU of total bacteria per 25 cm2 or the presence of Staphylococcus aureus. Two selected mask models maintained the expected mask performance equivalent to the FFP2 standard after reprocessing. Thermal reprocessing resulted in a virucidal effect. The results show that reprocessing of FFP masks in hospitals is possible. However, the success of reprocessing depends on the type of mask used. This study identified a suitable mask type for which the reported method is bactericidal and virucidal without impairing mask performance. The reported method required the use of a stationary hospital bed reprocessing chamber (sanitizing washer), so it cannot be used everywhere. Other methods and procedures should be tested to be independent of a bed reprocessing chamber and therefore may be more mobile and flexible.

In their own words: a qualitative survey of healthcare providers' experiences with personal protective equipment during the COVID-19 pandemic

BACKGROUND

At the beginning of the coronavirus disease (COVID-19) pandemic, healthcare personnel (HCP) faced a dire shortage of personal protective equipment (PPE). This shortage has been identified as a major source of distress among HCP during the early COVID-19 pandemic, though the specific consequences of this shortage have not been identified in the qualitative literature.

METHODS

We sought to fill this gap by conducting a qualitative analysis of PPE related free-text comments from online surveys completed by 923 HCP during Spring 2020.

RESULTS

We found that HCP used words such as "required" and "had" to describe how their use of non-standard PPE was imposed on them by their workplace, suggesting that they felt little control over their protection at work. HCP described cleaning PPE with novel methods, such as bleach, alcohol, hydrogen peroxide, and UV light, in addition to creating their own PPE out of materials such as garbage bags, sheets, and cloth. Furthermore, HCP expressed frustration with PPE policies at their workplaces, which continued throughout the early pandemic due to the rapidly changing guidelines and the inability to express their opinions to their institutions. The combination of these concerns left HCP scared of being infected with COVID-19 while at work and subsequently infecting their loved ones at home.

CONCLUSION

It is critical that healthcare institutions understand HCP's experiences with and feelings towards PPE, as providing the proper protection is vital in ensuring an adequate HCP workforce.

Bioburden Variation of Filtering Face Piece Respirators over Time: A Preliminary Study

BACKGROUND

The microbial contamination of a respirator can be evaluated through a count of the number of bacteria living on a non-sterilized surface (bioburden). This preliminary study investigated the external contamination of two different FFP2s over time by studying the bioburden values in increasing exposure times.

METHODS

FFP2 respirators of two different brands were used during routine clinical settings and examined through the bioburden test; for each brand, three devices were tested at 8, 16, and 30 h.

RESULTS

No significant differences were observed between mask brands (p = 0.113). There were only significant CFU differences between each mask and its control (p = 0.027 and p = 0.004).

CONCLUSIONS

Both brands of respirators were found to be contaminated and this contamination increased with the increase in exposure time. Further studies are needed to investigate the exact amount of contamination that could be considered acceptable before discarding each used mask.

Decontamination Assessment of Nanofiber-based N95 Masks

As the world battles with the outbreak of the novel coronavirus, it also prepares for future global pandemics that threaten our health, economy, and survivor. During the outbreak, it became evident that use of personal protective equipment (PPE), specially face masks, can significantly slow the otherwise uncontrolled spread of the virus. Nevertheless, the outbreak and its new variants have caused shortage of PPE in many regions of the world. In addition, waste management of the enormous economical and environmental footprint of single use PPE has proven to be a challenge. Therefore, this study advances the theme of decontaminating used masks. More specifically, the effect of various decontamination techniques on the integrity and functionality of nanofiber-based N95 masks (i.e. capable of at least filtering 95% of 0.3 μm aerosols) were examined. These techniques include 70% ethanol, bleaching, boiling, steaming, ironing as well as placement in autoclave, oven, and exposure to microwave (MW) and ultraviolet (UV) light. Herein, filtration efficiency (by Particle Filtration Efficiency equipment), general morphology, and microstructure of nanofibers (by Field Emission Scanning Electron microscopy) prior and after every decontamination technique were observed. The results suggest that decontamination of masks with 70% ethanol can lead to significant unfavorable changes in the microstructure and filtration efficiency (down to 57.33%) of the masks. In other techniques such as bleaching, boiling, steaming, ironing and placement in the oven, filtration efficiency dropped to only about 80% and in addition, some morphological changes in the nanofiber microstructure were seen. Expectedly, there was no significant reduction in filtration efficiency nor microstructural changes in the case of placement in autoclave and exposure to the UV light. It was concluded that, the latter methods are preferable to decontaminate nanofiber-based N95 masks.

Surface Inactivation of Human Coronavirus by MACOMA™ UVA-TiO2 Coupled Photocatalytic Disinfection System

There is an immense healthcare challenge and financial pressure due to the COVID-19 pandemic caused by a newly identified human coronavirus, SARS-CoV-2. Effective COVID-19 prevention efforts in healthcare, home, and community settings highlight the need for rapid, efficient, and no-contact SARS-CoV-2 inactivation strategies. Here, we examined the photocatalytic and virucidal activity of the MACOMA™ TiO2 photocatalytic film activated by an UVA-LED-12V-367 nm (MA-717836-1) lamp against the HCoV-OC43, a member of the beta coronaviruses family, like SARS-CoV-2, using quantitative RT-qPCR and virus infectivity assays. The UVA radiation-responsive TiO2 film accelerated virus inactivation (decreased viral titer) compared to the uncoated glass surface when placed at a vertical distance of 1.2 feet (~14 inches) from virus samples for 10, 30, and 60 min. UVA-LED exposure for both 10 and 30 min effectively reduced the viral RNA copies and the infectious virus in samples on TiO2-coated surfaces compared to the control surfaces. Importantly, a 60 min exposure of samples on the TiO2 completely eliminated HCoV-OC43. These results confirmed that the MACOMA™ UVA/TiO2-based disinfection system provides a rapid and complete surface inactivation of tested human coronavirus in a human-safe manner and has great potential for limiting the virus spread in poorly ventilated as well as high-traffic public places.