Reusability of filtering facepiece respirators after decontamination through drying and germicidal UV irradiation

Recycling of Anti-COVID-19 Filtering Facepiece Respirators for Use as Preliminary Water Filters

Although the United Nations has set sustainable management of water as an important worldwide goal, methods to supply clean water to underdeveloped countries are generally lacking. The ongoing COVID-19 pandemic as increased the worldwide use of filtering facepiece respirators (FFRs), resulting in enormous amounts of plastic waste. The present study tested whether FFRs could be recycled for use as preliminary water filters. Filtering of contaminated water with FFRs significantly reduced its turbidity, as well as concentrations of total organic carbon and major pollutants such as P, K, Mg, and Fe. Most of the filtered samples satisfied the drinking water quality standards of the World Health Organization. The additional use of FFRs decontamination process with hydrogen peroxide or ultraviolet germicidal irradiation, and sterilization with water purification tablets can eliminate disease-causing microorganisms and further reduce turbidity that would make water suitable for drinking. Recycling anti-COVID-19 FFRs for use as preliminary water filters is an effective and sustainable method for solving both drinking water problems and waste due to FFRs.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s41742-023-00526-w.

Evaluating the effects of air disinfectants in decontamination of COVID-19 aerosols

Introduction

Airborne transmission is the most  crucial mode of COVID-19 transmission. Therefore, disinfecting the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) aerosols float can have important implications in limiting COVID-19 transmission. Herein, we aimed to review the studies that utilized various disinfectants to decontaminate and inactivate the SARS-CoV-2 aerosols.

Methods

This study was a review that studied related articles published between December 1, 2019 and August 23, 2022. We searched the online databases of PubMed, Scopus, Web of Science, Cochrane, on August 23, 2021. The studies were downloaded into the EndNote software, duplicates were removed, and then the studies were screened based on the inclusion/exclusion criteria. The screening process involved two steps; first, the studies were screened based on their title and abstract and then their full texts. The included studies were used for the qualitative analysis.

Results

From 664 retrieved records, only 31 met the inclusion criteria and were included in the final qualitative analysis. Various materials like Ozone, H₂O₂, alcohol, and TiO₂ and methods like heating and using Ultraviolet were described in these studies to disinfect places contaminated by COVID-19. It appeared that the efficacy of these disinfectants varies considerably depending on the situation, time, and ultimately their mode of application.

Conclusion

Following reliable protocols in combination with the proper selection of disinfectant agents for each purpose would serve to achieve desired elimination of the SARS-CoV-2 transmission.

What We Are Learning from COVID-19 for Respiratory Protection: Contemporary and Emerging Issues

Infectious respiratory diseases such as the current COVID-19 have caused public health crises and interfered with social activity. Given the complexity of these novel infectious diseases, their dynamic nature, along with rapid changes in social and occupational environments, technology, and means of interpersonal interaction, respiratory protective devices (RPDs) play a crucial role in controlling infection, particularly for viruses like SARS-CoV-2 that have a high transmission rate, strong viability, multiple infection routes and mechanisms, and emerging new variants that could reduce the efficacy of existing vaccines. Evidence of asymptomatic and pre-symptomatic transmissions further highlights the importance of a universal adoption of RPDs. RPDs have substantially improved over the past 100 years due to advances in technology, materials, and medical knowledge. However, several issues still need to be addressed such as engineering performance, comfort, testing standards, compliance monitoring, and regulations, especially considering the recent emergence of pathogens with novel transmission characteristics. In this review, we summarize existing knowledge and understanding on respiratory infectious diseases and their protection, discuss the emerging issues that influence the resulting protective and comfort performance of the RPDs, and provide insights in the identified knowledge gaps and future directions with diverse perspectives.

Acaricidal efficacy of ultraviolet-C irradiation of Tetranychus urticae adults and eggs using a pulsed krypton fluoride excimer laser

BACKGROUND

Pulsed ultraviolet (UV)-C light sources, such as excimer lasers, are used in emerging non-thermal food-decontamination methods and also have high potential for use in a wide range of microbial decontamination applications. The acaricidal effect of an experimental UV-C irradiation device was assessed using female adults and eggs of a model organism, the two-spotted spider mite Tetranychus urticae.

METHODS

UV-C light was generated by a pulsed krypton fluoride excimer laser operating at 248-nm emission wavelength. The pulse energy and pulse repetition rate were 5 mJ and up to 100 Hz, respectively. The distance from the light source to the target was 150 mm; the target surface area was 2.16 cm2. The exposure time for the mites and fresh eggs varied from 1 to 4 min at 5-300 mW, which corresponded to UV doses of 5-80 kJ/m2. Post-irradiation acaricidal effects (mite mortality) were assessed immediately and also measured at 24 h. The effects of UV-C irradiation on the hatchability of eggs were observed daily for up to 12 days post-irradiation.

RESULTS

The mortality of mites at 5 and 40 kJ/m2 was 26% and 92%, respectively. Mite mortality reached 98% at 80 kJ/m2. The effect of exposure duration on mortality was minimal. The effect of irradiation on egg hatchability was even more significant than that on adult mite mortality, i.e. about 100% egg mortality at an accumulated dose of as little as 5 kJ/m2 for each exposure time.

CONCLUSIONS

A high rate of mite mortality and lethal egg damage were observed after less than 1 min of exposure to 5 mJ UV-C pulsed irradiation at 60 Hz. Pending further developments (such as beam steering, beam shaping and miniaturisation) and feasibility studies (such as testing with mites in real-life situations), the reported results and characteristics of the UV-C generator (modulation of energy output and adaptability to varying spot sizes) open up the use of this technology for a vast field of acaricidal applications that require long-range radiation.

Decontaminating N95/FFP2 masks for reuse during the COVID-19 epidemic: a systematic review

BACKGROUND

With the current COVID-19 pandemic, many healthcare facilities have been lacking a steady supply of filtering facepiece respirators. To better address this challenge, the decontamination and reuse of these respirators is a strategy that has been studied by an increasing number of institutions during the COVID-19 pandemic.

METHODS

We conducted a systematic literature review in PubMed, PubMed Central, Embase, and Google Scholar. Studies were eligible when (electronically or in print) up to 17 June 2020, and published in English, French, German, or Spanish. The primary outcome was reduction of test viruses or test bacteria by log3 for disinfection and log6 for sterilization. Secondary outcome was physical integrity (fit/filtration/degradation) of the respirators after reprocessing. Materials from the grey literature, including an unpublished study were added to the findings.

FINDINGS

Of 938 retrieved studies, 35 studies were included in the analysis with 70 individual tests conducted. 17 methods of decontamination were found, included the use of liquids (detergent, benzalkonium chloride, hypochlorite, or ethanol), gases (hydrogen peroxide, ozone, peracetic acid or ethylene oxide), heat (either moist with or without pressure or dry heat), or ultra violet radiation (UVA and UVGI); either alone or in combination. Ethylene oxide, gaseous hydrogen peroxide (with or without peracetic acid), peracetic acid dry fogging system, microwave-generated moist heat, and steam seem to be the most promising methods on decontamination efficacy, physical integrity and filtration capacity.

INTERPRETATION

A number of methods can be used for N95/FFP2 mask reprocessing in case of shortage, helping to keep healthcare workers and patients safe. However, the selection of disinfection or sterilization methods must take into account local availability and turnover capacity as well as the manufacturer; meaning that some methods work better on specific models from specific manufacturers.

SYSTEMATIC REGISTRATION NUMBER

CRD42020193309.

The COVID-19 pandemic and N95 masks: reusability and decontamination methods

BACKGROUND

With the current SARS-CoV-2 pandemic, many healthcare facilities are lacking a steady supply of masks worldwide. This emergency situation warrants the taking of extraordinary measures to minimize the negative health impact from an insufficient supply of masks. The decontamination, and reuse of healthcare workers' N95/FFP2 masks is a promising solution which needs to overcome several pitfalls to become a reality.

AIM

The overall aim of this article is to provide the reader with a quick overview of the various methods for decontamination and the potential issues to be taken into account when deciding to reuse masks. Ultraviolet germicidal irradiation (UVGI), hydrogen peroxide, steam, ozone, ethylene oxide, dry heat and moist heat have all been methods studied in the context of the pandemic. The article first focuses on the logistical implementation of a decontamination system in its entirety, and then aims to summarize and analyze the different available methods for decontamination.

METHODS

In order to have a clear understanding of the research that has already been done, we conducted a systematic literature review for the questions: what are the tested methods for decontaminating N95/FFP2 masks, and what impact do those methods have on the microbiological contamination and physical integrity of the masks? We used the results of a systematic review on the methods of microbiological decontamination of masks to make sure we covered all of the recommended methods for mask reuse. To this systematic review we added articles and studies relevant to the subject, but that were outside the limits of the systematic review. These include a number of studies that performed important fit and function tests on the masks but took their microbiological outcomes from the existing literature and were thus excluded from the systematic review, but useful for this paper. We also used additional unpublished studies and internal communication from the University of Geneva Hospitals and partner institutions.

RESULTS

This paper analyzes the acceptable methods for respirator decontamination and reuse, and scores them according to a number of variables that we have defined as being crucial (including cost, risk, complexity, time, etc.) to help healthcare facilities decide which method of decontamination is right for them.

CONCLUSION

We provide a resource for healthcare institutions looking at making informed decisions about respirator decontamination. This informed decision making will help to improve infection prevention and control measures, and protect healthcare workers during this crucial time. The overall take home message is that institutions should not reuse respirators unless they have to. In the case of an emergency situation, there are some safe ways to decontaminate them.

Ultraviolet-C as a Viable Reprocessing Method for Disposable Masks and Filtering Facepiece Respirators

In normal conditions, discarding single-use personal protective equipment after use is the rule for its users due to the possibility of being infected, particularly for masks and filtering facepiece respirators. When the demand for these protective tools is not satisfied by the companies supplying them, a scenario of shortages occurs, and new strategies must arise. One possible approach regards the disinfection of these pieces of equipment, but there are multiple methods. Analyzing these methods, Ultraviolet-C (UV-C) becomes an exciting option, given its germicidal capability. This paper aims to describe the state-of-the-art for UV-C sterilization in masks and filtering facepiece respirators. To achieve this goal, we adopted a systematic literature review in multiple databases added to a snowball method to make our sample as robust as possible and encompass a more significant number of studies. We found that UV-C's germicidal capability is just as good as other sterilization methods. Combining this characteristic with other advantages makes UV-C sterilization desirable compared to other methods, despite its possible disadvantages.