VAPOUR COUGH VISUALIZATION FOR COVID-19 – COMPUTATIONAL MODELLING APPROACH

New Zealand and many countries gained heightened awareness of indoor air quality (IAQ) issues, and increased investment, according to the World Health Organization (WHO) guidelines, to improve their IAQ and reduce air pollution in commercial and residential buildings. Additionally, some countries have introduced new standards for indoor environments, such as the New Zealand "healthy homes” standard. At the same time, COVID-19 pandemic forced many people to spend much more time in indoor spaces, due to stay-at-home, or lockdown orders by governments. This increased attention on other aspects of indoor environmental quality, such as occupants' satisfaction with thermal comfort parameters, presents an additional parameter for research and in the development of standards. From a medical perspectives, infectious respiratory diseases, such as influenza or COVID-19, are transmitted by airborne droplets. In this work, we assess a Polyester Filter and UV light (PFUV) dehumidifier device performance in an office with two occupants (one uninfected and the other one infected with a disease with airborne transmission using computational fluid dynamics (CFD) approach. Two positions for locating the PFUV dehumidifier in an office with a scenario in which one person is exhaling infected air and the other occupant must inhale and exhale from the shared air. The CFD model illustrated the best position of the device to distribute the air velocity contours. Further, based on the CFD model which was validated via the IAQ and comfort kit (Testo 400) thermal comfort analysis showed that the room is slightly cold. Copyright © 2022 by ASME.

Model Evaluation of Secondary Chemistry due to Disinfection of Indoor Air with Germicidal Ultraviolet Lamps

Air disinfection using germicidal ultraviolet light (GUV) has received increasing attention during the COVID-19 pandemic. GUV uses UVC lamps to inactivate microorganisms, but it also initiates photochemistry in air. However, GUV's indoor-air-quality impact has not been investigated in detail. Here, we model the chemistry initiated by GUV at 254 ("GUV254”) or 222 nm ("GUV222”) in a typical indoor setting for different ventilation levels. Our analysis shows that GUV254, usually installed in the upper room, can significantly photolyze O3, generating OH radicals that oxidize indoor volatile organic compounds (VOCs) into more oxidized VOCs. Secondary organic aerosol (SOA) is also formed as a VOC-oxidation product. GUV254-induced SOA formation is of the order of 0.1-1 μg/m3 for the cases studied here. GUV222 (described by some as harmless to humans and thus applicable for the whole room) with the same effective virus-removal rate makes a smaller indoor-air-quality impact at mid-to-high ventilation rates. This is mainly because of the lower UV irradiance needed and also less efficient OH-generating O3 photolysis than GUV254. GUV222 has a higher impact than GUV254 under poor ventilation due to a small but significant photochemical production of O3 at 222 nm, which does not occur with GUV254. © 2022 American Chemical Society.

COVID-19 pandemic lesson learned- critical parameters and research needs for UVC inactivation of viral aerosols.

The COVID-19 pandemic highlighted public awareness of airborne disease transmission in indoor settings and emphasized the need for reliable air disinfection technologies. This increased awareness will carry in the post-pandemic era along with the ever-emerging SARS-CoV variants, necessitating effective and well-defined protocols, methods, and devices for air disinfection. Ultraviolet (UV)-based air disinfection demonstrated promising results in inactivating viral bioaerosols. However, the reported data diversity on the required UVC doses has hindered determining the best UVC practices and led to confusion among the public and regulators. This article reviews available information on critical parameters influencing the efficacy of a UVC air disinfection system and, consequently, the required dose including the system's components as well as operational and environmental factors. There is a consensus in the literature that the interrelation of humidity and air temperature has a significant impact on the UVC susceptibility, which translate to changing the UVC efficacy of commercialized devices in indoor settings under varying conditions. Sampling and aerosolization techniques reported to have major influence on the result interpretation and it is recommended to use several sampling methods simultaneously to generate comparable and conclusive data. We also considered the safety concerns and the potential safe alternative of UVC, far-UVC. Finally, the gaps in each critical parameter and the future research needs of the field are represented. This paper is the first step to consolidating literature towards developing a standard validation protocol for UVC air disinfection devices which is determined as the one of the research needs.

A review on indoor environmental quality in sports facilities: Indoor air quality and ventilation during a pandemic

Because of COVID-19, the indoor environmental quality (IEQ) in sports facilities has been a concern to environmental health practitioners. To develop an overall understanding of the available guidelines and standards and studies performed on IEQ in sports facilities, an extensive literature study was conducted, with the aim of identifying: (1) indicators that are being used to assess IEQ in different sports facilities;(2) indicators that are potentially interesting to be used to assess indoor air, in particular;(3) gaps in knowledge to determine whether sports facilities are safe, healthy and comfortable for people to stay and perform their activities. The outcome indicates that most current standards and previous investigations on IEQ in sports facilities mainly focused on dose-related indicators (such as ventilation rate), while building-related indicators (such as ventilation regime) and occupant-related indicators (such as IEQ preferences) were rarely considered. Little attention is given to the fact that ventilation systems may play an important role in the air quality of the location, and few investigations have been performed on the transmission of SARS-CoV-2. This study recommends more research into both occupant and building-related indicators as well as cross-modal effects between various IEQ factors for developing future standards on sports facilities.

Model Evaluation of Secondary Chemistry due to Disinfection of Indoor Air with Germicidal Ultraviolet Lamps

Air disinfection using germicidal ultraviolet light (GUV) has received increasing attention during the COVID-19 pandemic. GUV uses UVC lamps to inactivate microorganisms, but it also initiates photochemistry in air. However, GUV's indoor-air-quality impact has not been investigated in detail. Here, we model the chemistry initiated by GUV at 254 ("GUV254") or 222 nm ("GUV222") in a typical indoor setting for different ventilation levels. Our analysis shows that GUV254, usually installed in the upper room, can significantly photolyze O3, generating OH radicals that oxidize indoor volatile organic compounds (VOCs) into more oxidized VOCs. Secondary organic aerosol (SOA) is also formed as a VOC-oxidation product. GUV254-induced SOA formation is of the order of 0.1-1 mu g/m3 for the cases studied here. GUV222 (described by some as harmless to humans and thus applicable for the whole room) with the same effective virus-removal rate makes a smaller indoor-air-quality impact at mid-to-high ventilation rates. This is mainly because of the lower UV irradiance needed and also less efficient OH-generating O3 photolysis than GUV254. GUV222 has a higher impact than GUV254 under poor ventilation due to a small but significant photochemical production of O3 at 222 nm, which does not occur with GUV254.

Sterilizable and Reusable UV-Resistant Graphene-Polyurethane Elastomer Composites.

Shortages of personal protective equipment (PPE) at the start of the COVID-19 pandemic caused medical workers to reuse medical supplies such as N95 masks. While ultraviolet germicidal irradiation (UVGI) is commonly used for sterilization, UVGI can also damage the elastomeric components of N95 masks, preventing effective fit and thus weakening filtration efficacy. Although PPE shortage is no longer an acute issue, the development of sterilizable and reusable UV-resistant elastomers remains of high interest from a long-term sustainability and health perspective. Here, graphene nanosheets, produced by scalable and sustainable exfoliation of graphite in ethanol using the polymer ethyl cellulose (EC), are utilized as UV-resistant additives in polyurethane (PU) elastomer composites. By increasing the graphene/EC loading up to 1 wt %, substantial UV protection is imparted by the graphene nanosheets, which strongly absorb UV light and hence suppress photoinduced degradation of the PU matrix. Additionally, graphene/EC provides mechanical reinforcement, such as increasing Young's modulus, elongation at break, and toughness, with negligible changes following UV exposure. These graphene/EC-PU composites remain mechanically robust over at least 150 sterilization cycles, enabling safe reuse following UVGI. Beyond N95 masks, these UVGI-compatible graphene/EC-PU composites have potential utility in other PPE applications to address the broader issue of single-use waste.

Development and experimental validation of an improved mathematical irradiance model for in-duct ultraviolet germicidal irradiation (UVGI) applications

The application of ultraviolet germicidal irradiation (UVGI) technology inside the heating, ventilation, and air-conditioning (HVAC) air ducts to purify circulating air and improve indoor air quality has attracted extensive interest during the COVID-19 pandemic. In this study, a new view-factor-based mathematical model was developed to calculate the irradiation distribution for a typical twin-tube UV lamp placed at the center of a square duct, in which the contributions from direct emissive irradiance, specular reflection irradiance, and diffuse reflection irradiance were quantified. Furthermore, the “projection area” method was introduced to mathematically estimate the shadowing effects between the two lamps by considering multiple-lamp scenarios in real in-duct UVGI system designs. Subsequently, a computational fluid dynamics (CFD) simulation was employed to compute the average received UV dose and disinfection efficiency of the system. The mathematical model combined with the CFD simulation was validated using the experimental data. It is concluded that by increasing the UV lamps, UV lamp power, and using more reflective duct wall materials, the in-duct UVGI disinfection performance can be improved. For the multiple-lamp arrangements, placing lamps perpendicular to the airflow in the same row results in a more uniform irradiance distribution and higher overall irradiation than placing them in different rows along the duct, thus increasing the disinfection efficiency. In addition, the duct wall with highly diffusive reflection provides a more uniform irradiance distribution and overall higher average radiation, thus providing better disinfection performance for an in-duct UVGI reactor.

Rapid disinfection of radiology treatment rooms using an autonomous ultraviolet germicidal irradiation robot.

BACKGROUND: Ultraviolet germicidal irradiation (UVGI) technologies have emerged as a promising adjunct to manual cleaning, however, their potential to shorten cleaning times remains unexplored. METHODS: A <10-minute disinfection procedure was developed using a robotic UVGI platform. The efficacy and time to perform the UVGI procedure in a CT scan treatment room was compared with current protocols involving manual disinfection using biocides. For each intervention, environmental samples were taken at 12 locations in the room before and after disinfection on seven distinct occasions. RESULTS: The mean UVC dose at each sample location was found to be 13.01 ± 4.36 mJ/cm2, which exceeded published UVC thresholds for achieving log reductions of many common pathogens. Significant reductions in microbial burden were measured after both UVGI (P≤.001) and manual cleaning (P≤.05) conditions, with the UVGI procedure revealing the largest effect size (r = 0.603). DISCUSSION: These results support the hypothesis that automated deployments of UVGI technology can lead to germicidal performance that is comparable with, and potentially better than, current manual cleaning practices. CONCLUSIONS: Our findings provide early evidence that the incorporation of automated UVGI procedures into cleaning workflow could reduce turnaround times in radiology, and potentially other hospital settings.

Did You Just Cough? Visualization of Vapor Diffusion in an Office Using Computational Fluid Dynamics Analysis.

Awareness of indoor air quality (IAQ) in crowded places such as schools and offices has increased since 2020 due to the COVID-19 pandemic. In addition, countries' shifting away from containment and towards living with COVID-19 is expected to increase demand for risk mitigation via air-purification devices. In this work, we use Computational Fluid Dynamics (CFD) analysis to investigate the impact of adding an air-purification technology on airflow in an enclosed space. We model a Polyester Filter and UV light (PFUV) dehumidifier in an office with two occupants: one infected with an airborne infectious disease, such as COVID-19; and the other uninfected. We compare three cases where the infected occupant coughs: with no device, and with the device at two different orientations. We construct a CFD model using ANSYS® 2021 Fluent and the Discrete Phase Model (DPM) for the particle treatment. Thermal comfort is assessed using the Testo 400 IAQ and comfort kit. We find that both the device operation and the placement alter the airflow contours, significantly reducing the potential for the uninfected occupant to inhale the vapour expelled by the infected occupant, potentially impacting the likelihood of disease transmission. The device improved thermal comfort measured by Predicted Mean Vote (PMV), Predicted Percentage Dissatisfied (PPD).

A simple multiparametric analysis to guide, compare and optimize the design of "lensless" LED illuminators

LED lighting is becoming increasingly pervasive in many areas ranging from ambient lighting, up to applications such as microscope illumination, UV-LED curing and, UV disinfection for air, surfaces, and water. Irradiance uniformity is often a fundamental parameter for guiding the design, comparison, and optimization of the illuminator. To this end, many methods and procedures have been proposed to guide the arrangement of the LED sources, as well as to guide the design of ad-hoc lenses. Nevertheless, there are many applications in which it is important to be able to consider other aspects as well as the uniformity of the irradiance. For this purpose, we propose both a method that allows calculating the irradiance generated by the used LED sources and, performance indicators for guiding the design and comparing different optical layouts.

Field study of early implementation of UV sources and their relative effectiveness for public health and safety.

The emergence of COVID-19 and its corresponding public health burden has prompted industries to rapidly implement traditional and novel control strategies to mitigate the likelihood of SARS-CoV-2 transmission, generating a surge of interest and application of ultraviolet germicidal irradiation (UVGI) sources as disinfection systems. With this increased attention the need to evaluate the efficacy and safety of these types of devices is paramount. A field study of the early implementation of UVGI devices was conducted at the Space Needle located in Seattle, Washington. Six devices were evaluated, including four low-pressure (LP) mercury-vapor lamp devices for air and surface sanitation not designed for human exposure and two krypton chloride (KrCl*) excimer lamp devices to be operated on and around humans. Emission spectra and ultraviolet (UV) irradiance at different locations from the UV devices were measured and germicidal effectiveness against SARS-CoV-2 was estimated. The human safety of KrCl* excimer devices was also evaluated based on measured irradiance and estimated exposure durations. Our results show all LP devices emitted UV radiation primarily at 254 nm as expected. Both KrCl* excimers emitted far UVC irradiation at 222 nm as advertised but also emitted at longer, more hazardous wavelengths (228 to 262 nm). All LP devices emitted strong UVC irradiance, which was estimated to achieve three log reduction of SARS-CoV-2 within 10 sec of exposure at reasonable working distances. KrCl* excimers, however, emitted much lower irradiance than needed for effective disinfection of SARS-CoV-2 (>90% inactivation) within the typical exposure times. UV fluence from KrCl* excimer devices for employees was below the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) under the reported device usage and work shifts. However, photosensitive individuals, human susceptibility, or exposure to multiple UV sources throughout a worker's day, were not accounted for in this study. Caution should be used when determining the acceptability of UV exposure to workers in this occupational setting and future work should focus on UVGI sources in public settings.

Airborne Disinfection Solution During New Normal Face-To-Face Learning

Communities have had to make concerns when and how schools serving students in schools and campus should re-open against temporary closure to slow the spread of COVID-19 virus. Apart from continuing COVID-19 health protocols for all students, teachers and staffs, technology support needed for air circulation disinfection in crowded and inadequately ventilated space like a classroom. This study examines the impact of using UVC tools and combine with evidence-based source control practices, whether refine indoor air quality to best minimize exposure risk to COVID-19 for staff and students. This study found airborne disinfection can be solved through UVC irradiation with measured radiation 7,31 mW/cm2 since previous published research only need 5 mW/cm2 at least one second. The recommendation from this study, government need to raise public policy for education institutions to apply ultraviolet germicidal irradiation (UVGI) chamber to cut-off virus airborne transmission by circulating and disinfect indoor air during in-class activities all day long. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Numerical model of the irradiance field surrounding a UV disinfection robot.

Objective.New technologies, including robots comprising germ-killing UV lamps, are increasingly being used to decontaminate hospitals and prevent the spread of COVID-19 and other superbugs. Existing approaches for modelling the irradiance field surrounding mobile UV disinfection robots are limited by their inability to capture the physics of their bespoke geometrical configurations and do not account for reflections. The goal of this research was to extend current models to address these limitations and to subsequently verify these models using empirically collected data.Approach.Two distinct parametric models were developed to describe a multi-lamp robotic UV system and adapted to incorporate the effects of irradiance amplification from the device's reflectors. The first model was derived from electromagnetic wave theory while the second was derived from conservation of energy and diffusion methods. Both models were tuned using data from empirical testing of an existing UV robot, and then validated using an independent set of measurements from the same device.Results.For each parameter, predictions made using the conservation of energy method were found to closely approximate the empirical data, offering more accurate estimates of the 3D irradiance field than the electromagnetic wave theory model.Significance.The versatility of the proposed method ensures that it can be easily adapted to different embodiments, providing a systematic way for researchers to develop accurate numerical models of custom UV robots, which may be used to inform deployment and/or to improve the accuracy of virtual simulation.

Ultraviolet Germicidal Irradiation (UVGI) Application in Building Design to Terminate Pathogens Naturally

Advanced building design technology is being proposed to eliminate all pathogens, including COVID-19, inside buildings naturally before they attack the human body. Pathogens comprise viruses, fungi, molds, protozoans, and bacteria that cause deadly diseases in humans. Thus, in this research, the application of solar irradiance through an outer glazing wall of the building forming Ultraviolet Germicidal Irradiation (UVGI) derived from sunlight has been performed to eliminate all pathogens inside the buildings before the pathogens attack the human body to cause deadly disease. Based on the findings that all pathogens, including COVID-19, can be killed with short-range wavelengths of 254-280 UVGI by disrupting their nucleic acid bonds, the pathogens are forced to malfunction in their biochemical functions and eventually the pathogens are caused to die. Simply, utilization of the outer glazing wall of a building to kill pathogens by controlling the photophysical reaction shall indeed be an interesting field of science to eliminate pathogens inside the building before those pathogens penetrate the human body.

Disinfection of Respirators with Ultraviolet Radiation

Data for interpreting virus inactivation on N95 face filtering respirators (FFRs) by ultraviolet (UV) radiation are important in developing UV strategies for N95 FFR disinfection and reuse for any situation, whether it be everyday practices, contingency planning for expected shortages, or crisis planning for known shortages. Data regarding the integrity, form, fit, and function of N95 FFR materials following UV radiation exposure are equally important. This article provides these data for N95 FFRs following UV-C irradiation (200 nm to 280 nm) in a commercial UV-C enclosure. Viral inactivation was determined by examining the inactivation of OC43, a betacoronavirus, inoculated on N95 FFRs. Different metrological approaches were used to examine irradiated N95 FFRs to determine if there were any discernible physical differences between non-irradiated N95 FFRs and those irradiated using the UV-C enclosure. Material integrity was examined using high-resolution scanning electron microscopy. Form, fit, and function were examined using flow resistance, tensile strength, and particle filtration measurements. A separate examination of filter efficiency, fit, and strap tensile stress measurements was performed by the National Personal Protective Technology Laboratory. Data from these metrological examinations provide evidence that N95 FFR disinfection and reuse using the UV-C enclosure can be effective.

A comparative empirical analysis of low-cost decontamination methods for filtering facepiece respirators to address stock shortages during the COVID-19 Pandemic

Introduction: Filtering facepiece respirators (FFRs) reuse practices to address shortages during the COVID-19 pandemic received attention;however, evidence of SARS-CoV-2 inactivation on respirators is limited. Quality FFRs for use during outbreaks remains a priority to protect frontline and essential workers. This study aimed to compare the effectiveness of three relatively inexpensive methods to inactivate SARS-CoV-2 and ensuring respirator performance. Methods: Seven FFRs inoculated with SARS-CoV-2 were decontaminated with moist heat incubation (MHI), vapourised hydrogen peroxide (VHP), and ultraviolet germicidal irradiation (UVGI). G.stearothermophilus bioindicator was used as a control. FFR integrity, efficiency and user fit were assessed on 27 participants for 30 decontamination cycles. Ethical clearance was acquired from the University of the Witwatersrand (M200684). Results: Most participants failed fit testing for KN95 irrespective of method used except for two individuals. Participants completed more cycles after UVGI compared to VHP decontamination. Only KN95 failed filtration post-MHI, VHP and UVGI treatment. A ≥ 3 log reduction of SARS-CoV-2 was achieved using UVGI for worn FFRs (Greenline 5200 FFP2 and Makrite 9500 N95 using MHI;3M 8810SSA FFP2 using VHP;Greenline 5200 FFP2). UVGI and VHP methods achieved a 6 log reduction of G.stearothermophilus. Conclusion: Some FFRs could withstand 30 cycles of UVGI and VHP processing without diminishing filtration efficiency or fit. SARS-CoV-2 log reduction varied across the methods and FFRs models emphasing the importance of validation before reuse during a crisis.

Preventing Tuberculosis (TB) in health workers and silica-exposed occupations

The COVID-19 pandemic has reminded us of the importance of workplace exposures and transmission in the control of airborne infectious diseases. The importance of workplace transmission of Tuberculosis (TB) has been well documented for decades, yet these past lessons have largely gone unheeded for health workers and silica-exposed occupations which are some of the highest risk subpopulations. It is estimated that health care workers who represent 3% of the global population made up 14% of reported COVID-19 and the same front-line workers are at three times greater risk for active TB compared to the general population. Despite these known risks, multiple studies have demonstrated that few health workers are provided with training or protections. Workplace TB prevention measures overlap with measures known to reduce the spread of COVID-19 and include improved ventilation, UV germicidal irradiation, personal protective equipment and training. These dual pandemics present an opportunity to refocus investment in Infection Prevention Control (IPC) measures in healthcare settings. Silica dust exposures and silicosis are known to significantly increase the risk of active TB among miners, construction workers and other exposed occupations. Reducing silica dust exposures has been shown to reduce TB incidence in high-risk workers. Recent studies have demonstrated that informal sector miners experience much higher rates of TB infection than large-scale miners. However, low-cost dust controls have been shown to reduce respirable silica dust by 80% which can have a large impact in reducing TB and silicosis. Workplace interventions to reduce TB in healthcare setting and among silica-exposed workers are cost effective and are considerably less expensive than treatment. The International Commission on Occupational Health (ICOH) has been taking an active role in working to increase recognition of workplace interventions to reduce TB transmission. Starting in 2017 the organization spear-headed efforts at the United Nations (UN) to gain recognition for workplace interventions in the General Assembly TB declaration (2018) and has since engaged with UN agencies, the World Bank and other global TB funding organizations. There is a considerable need to expand primary prevention in the workplace as part of the global TB response.

An overview of solutions for airborne viral transmission reduction related to HVAC systems including liquid desiccant air-scrubbing.

The spread of the coronavirus SARS-CoV-2 affects the health of people and the economy worldwide. As air transmits the virus, heating, ventilation and air-conditioning (HVAC) systems in buildings, enclosed spaces and public transport play a significant role in limiting the transmission of airborne pathogens at the expenses of increased energy consumption and possibly reduced thermal comfort. On the other hand, liquid desiccant technology could be adopted as an air scrubber to increase indoor air quality and inactivate pathogens through temperature and humidity control, making them less favourable to the growth, proliferation and infectivity of microorganisms. The objectives of this study are to review the role of HVAC in airborne viral transmission, estimate its energy penalty associated with the adoption of HVAC for transmission reduction and understand the potential of liquid desiccant technology. Factors affecting the inactivation of pathogens by liquid desiccant solutions and possible modifications to increase their heat and mass transfer and sanitising characteristics are also described, followed by an economic evaluation. It is concluded that the liquid desiccant technology could be beneficial in buildings (requiring humidity control or moisture removal in particular when viruses are likely to present) or in high-footfall enclosed spaces (during virus outbreaks).

Efficacy and Safety of Weekly Ultraviolet Germicidal Irradiation for the Reuse of N95 Filtering Respirators.

Background During the ongoing coronavirus disease (COVID-19) pandemic, N95 filtering facepiece respirators (N95 respirators) are in short supply in many countries. Considering this, the Centers for Disease Control and Prevention suggested reusing N95 respirators and recommended the use of ultraviolet germicidal irradiation (UVGI) for sterilizing the respirators. However, only a few reports have described UVGI protocols for sterilizing the N95 respirators for reuse. Therefore, in this study, we aimed to develop and evaluate a novel method for the reuse of N95 respirators after sterilization by UVGI. Methods Before conducting the study, the function of N95 respirators after multiple UVGI with a total dose of up to 10 J (1 J/cm2 or more per dose) was assessed by measuring the particle collection efficiency and ventilation resistance. The participants used N95 respirators during work if they passed the fit test. After use, the respirators were sterilized using UVGI (1 J/cm2) and stored in a breathable paper bag for a week. The procedure was repeated up to three times after confirming the successful results of the fit tests. Results The particle collection efficiency without UVGI was 96.7%, while those after one, five, and 10 cycles of UGVI were 96.8%, 97.2%, and 97.2%, respectively. Ventilation resistance without UVGI was 42 Pa, and 43 Pa, 42 Pa, and 41 Pa after one, five, and 10 cycles of UVGI, respectively, which satisfied the Japanese national certification standard DS2. All 43 participants passed the fit test before the first reuse, and 39 participants (90.7%) completed the entire study protocol. The results of this study showed that N95 respirators could be used safely after repeated UVGI treatment. Conclusions This study developed a novel method for reusing the N95 respirators. A few cycles of UV radiation N95 masks retain their functionalities and can be reused with proper UVGI.

A Practical Approach to Filtering Facepiece Respirator Decontamination and Reuse: Ultraviolet Germicidal Irradiation.

Purpose of review: Prior outbreaks of respiratory viruses have demonstrated the need for adequate personal protective equipment (PPE) for healthcare workers, particularly filtering facepiece respirators (FFR). Due to shortfalls of PPE during the SARS CoV-2 pandemic, the need for FFR decontamination and reuse (FFR-DR) strategies is paramount. This paper aims to discuss primary decontamination strategies, with an in-depth analysis of ultraviolet germicidal irradiation (UVGI), arriving at the decontamination strategy utilized at the Nebraska Medical Center (NMC). Methods: Review of the primary literature in regard to FFR-DR as well as a synopsis of the current protocol for FFR-DR at NMC. Recent findings: UVGI demonstrates effective decontamination of multiple pathogens-including several human respiratory viruses-while maintaining mask integrity and filtering capacity. UVGI was associated with degradation of strap integrity at higher doses than that utilized for decontamination or with reuse beyond 20 times. Summary: UVGI effectively decontaminates N95 FFRs without significant reduction to fit or strap integrity and can be employed as a strategy for FFR-DR in times of emergency.