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The long-term refrigerated storage of melted snow and/or ice samples for analyses of insoluble microparticles (hereafter, microparticles) may be limited by increases in the biological particle concentration caused by microbial growth after ~1–2 weeks. In this study, we examined an ultraviolet (UV) disinfection method for the storage of melted snow and/or ice samples and determined the effects of this method on microparticles. Surface snow obtained from Glacier No. 31 in the Suntar-Khayata Range, eastern Siberia, Russia was divided into two portions for UV treatment and untreated controls. Microparticle concentrations and size distributions (in the range of 0.52–12.0 μm) in the samples were measured using a Coulter counter. Whereas the microparticle concentration in untreated samples increased, no obvious increase was observed over 53 d in the samples subjected to UV treatment. Microbial growth was detected in only untreated samples using a viable particle counter. In addition, the original microparticle concentrations and size distributions were unaffected by UV treatment. Our results demonstrated that the microparticle size distribution in untreated melted water samples reflects the growth, decomposition and succession of microorganisms over time and further indicate that UV irradiation is effective for long-term storage for microparticle analysis.

One early problem during the height of the COVID‐19 global pandemic, caused by severe acute respiratory syndrome 2 (SARS‐CoV‐2), was the shortage of personal protective equipment donned by healthcare workers, particularly N95 respirators. Given the known virucidal, bactericidal, and fungicidal properties of ultraviolet irradiation, in particular ultraviolet C (UVC) radiation, our photomedicine and photobiology unit explored the role of ultraviolet germicidal irradiation (UVGI) using UVC in effectively decontaminating N95 respirators. The review highlights the important role of photobiology and photomedicine in this pandemic. Namely, the goals of this review were to highlight: UVGI as a method of respirator disinfection—specifically against SARS‐CoV‐2, adverse reactions to UVC and precautions to protect against exposure, other methods of decontamination of respirators, and the importance of respirator fit testing.

Mitigating the spread of infectious diseases such as the one associated with the COVID-19 pandemic demands simple and effective disinfection techniques. Ultraviolet germicidal irradiation (UVGI) is one such method, in common use for decontamination of hospital rooms. Practical technologies designed to monitor UVGI ensure the delivery of sufficient doses for germicidal efficacy. Existing UVGI dosimeters rely on intermittent measurements of intensity as the basis for a numerical integration scheme that approximates dose. Traditional devices are ineffective, particularly with pulsed UVGI lamps that emit pulses of light with durations shorter than the interval of measurement. Here, we present a compact, accumulation mode dosimeter (AMD) that detects continuously, as opposed to intermittently, at single or multiple UVGI wavelengths. The AMD utilizes an array of photodiodes and supercapacitors to passively transduce and capture photocurrent generated by UVGI without the use of external power. The accumulated voltage across the supercapacitors then serves as a measure of UVGI dose. A key result is that sampling intervals of AMD do not constrain measurement accuracy. When implemented with a wireless transponder, AMD supports a light-adaptive sampling scheme designed to adjust the sampling interval to the intensity and period of UVGI exposure. Compared to time-based sampling schemes adopted by conventional sensors, light-adaptive approaches autonomously optimize battery life by minimizing current consumption during periods of low or no UVGI. Benchtop studies of the use of this technology with pulsed Xenon lamps (pulse ~5 ms) sampled at long intervals (>1s) highlight the key features of operation. Demonstration of AMD during UVGI of ${E}$ . Coli cultures represents an example in dose dependent effects on disinfection.

Ultraviolet germicidal irradiation (UVGI) is an effective technique that can sterilize bacteria and viruses by UV light. Far UVC lamps of short wavelengths can prevent infectious diseases because they sterilize while minimizing cell damage in mammals. Here, E. coli inactivation by far UVC light with peak wavelength of 230 nm made of carbon nanotube (CNT) emitters and sapphire anode was studied. The κ-Al2O3 phase of sapphire with a direct band gap of 5.4 eV was excited with CNT-based cold cathode electron beam (C-beam) to generate far UVC light. It was confirmed that the inactivation of E. coli by far UVC light based on the C-beam was reduced by 5 log reduction within 60 s.

The information in this document is useful for HVAC professionals, facility engineers and specialists like employers and building owners and administrators seeking basic knowledge about ultraviolet germicidal irradiation (UVGI) technology. This article explains the specific terms used in the UV field, reasons why UVGI is used for virus inactivation and the main features of UV-C lamps. UVGI device typology is presented, and some general rules and limitations for safe usage are provided. Given the complexity of the UV transmission physics, specific software is needed for sizing UV systems. The sizing guidelines and design examples for different UV-C devices are not included in this document. This annexe scope is general and not limited to any specific building category (e.g., office buildings, educational buildings, shopping areas, sports premises, hospitals, healthcare settings, even residences). However, considering the negative effects on human health and some materials that UV-C radiation could generate when the design is defective, the most important rule is to use only certified products that are properly sized and tested.

To meet the educational, physical, social, and emotional needs of children, many U.S. schools opened for in-person learning during fall 2020 by implementing strategies to prevent transmission of SARS-CoV-2, the virus that causes COVID-19 (1,2). To date, there have been no U.S. studies comparing COVID-19 incidence in schools that varied in implementing recommended prevention strategies, including mask requirements and ventilation improvements* (2). Using data from Georgia kindergarten through grade 5 (K-5) schools that opened for in-person learning during fall 2020, CDC and the Georgia Department of Public Health (GDPH) assessed the impact of school-level prevention strategies on incidence of COVID-19 among students and staff members before the availability of COVID-19 vaccines.† Among 169 K-5 schools that participated in a survey on prevention strategies and reported COVID-19 cases during November 16-December 11, 2020, COVID-19 incidence was 3.08 cases among students and staff members per 500 enrolled students.§ Adjusting for county-level incidence, COVID-19 incidence was 37% lower in schools that required teachers and staff members to use masks, and 39% lower in schools that improved ventilation, compared with schools that did not use these prevention strategies. Ventilation strategies associated with lower school incidence included methods to dilute airborne particles alone by opening windows, opening doors, or using fans (35% lower incidence), or in combination with methods to filter airborne particles with high-efficiency particulate absorbing (HEPA) filtration with or without purification with ultraviolet germicidal irradiation (UVGI) (48% lower incidence). Multiple strategies should be implemented to prevent transmission of SARS-CoV-2 in schools (2); mask requirements for teachers and staff members and improved ventilation are important strategies that elementary schools could implement as part of a multicomponent approach to provide safer, in-person learning environments. Universal and correct mask use is still recommended by CDC for adults and children in schools regardless of vaccination status (2).

Background A major concern among health care experts is a shortage of N95 filtering facepiece respirators (FFRs) during a pandemic. One option for mitigating an FFR shortage is to decontaminate and reuse the devices. The focus of this study was to develop a new evaluation technique based on 3 major decontamination requirements: (1) inactivating viruses, (2) not altering the respirator properties, and (3) not leaving any toxic byproduct on the FFR. Methods Hydrophilic and hydrophobic FFRs were contaminated with MS2 virus. In the solution-based deposition, the virus-containing liquid droplets were spiked directly onto FFRs, while in the vapor-based and aerosol-based depositions, the viral particles were loaded onto FFRs using a bio-aerosol testing system. Ultraviolet germicidal irradiation (UVGI) and moist heat (MH) decontamination methods were used for inactivation of viruses applied to FFRs. Results Both UVGI and MH methods inactivated viruses (>5-log reduction of MS2 virus; in 92% of both method experiments, the virus was reduced to levels below the detection limit), did not alter the respirator properties, and did not leave any toxic byproduct on the FFRs. Conclusions Both UVGI and MH methods could be considered as promising decontamination candidates for inactivation of viruses for respirator reuse during shortages.

The COVID‐19 pandemic has greatly heightened interest in ultraviolet germicidal irradiation (UVGI) as an important intervention strategy to disinfect air in medical treatment facilities and public indoor spaces. However, a major drawback of UVGI is the challenge posed by assuring safe installation of potentially hazardous short‐wavelength (UV‐C) ultraviolet lamps. Questions have arisen regarding what appear to be unusually conservative exposure limit values in the UV‐C spectral band between 180 and 280 nm. We review the bases for the current limits and proposes some adjustments that would provide separate limits for the eye and the skin at wavelengths less than 300 nm and to increase both skin and eye limits in the UV‐C below 250 nm., The COVID‐19 pandemic revived interest in ultraviolet germicidal irradiation (UVGI) as an important intervention strategy to disinfect air in populated spaces. However, a major drawback of UVGI is the challenge posed by assuring safe installation of potentially hazardous short‐wavelength (UV‐C) ultraviolet lamps. Our review shows some unusually conservative exposure limit values in the UV‐C spectral band between 180 and 280 nm. We review the bases for current limits and propose separate limits for the eye and the skin for wavelengths less than 300 nm and propose increasing both skin and eye limits in the far UV‐C below 250 nm.

Ultraviolet germicidal irradiation uses ultraviolet C (UV-C) energy to disinfect surfaces in clinical settings. Verifying that the doses of UV-C energy received by surfaces are adequate for proper disinfection levels can be difficult and expensive. Our study aimed to test commercially available colorimetric labels, sensitive to UV-C energy, and compare their precision with an accepted radiometric technique. The color-changing labels were found to predictably change color in a dose-dependent manner that would allow them to act as a qualitative alternative to radiometry when determining the minimum UV-C energy dosage received at surfaces. If deployed using careful protective techniques to avoid unintentional exposure to sunlight or other light sources, the use of colorimetric labels could provide inexpensive, easy, and accurate verification of effective UV-C dosing in clinical spaces.

The response to the challenges arising during the COVID-19 pandemic has seen the rapid implementation of innovative technological solutions which have been built on established knowledge and resources. This has been reflected in infection, prevention and control practices (IPC) to minimise the transmission of the disease. In this article, we review ultraviolet germicidal irradiation (UVGI) as such a technology. We illustrate the way it has traditionally been used in airborne and surface disinfection strategies, and how it has, more recently, been adapted. UVGI has been widely used as an environmental IPC measure against tuberculosis in South Africa, though challenges have been experienced in the implementation of the technology in public healthcare facilities. This has resulted in the development of a knowledge and infrastructure base. We posit that, given the established UVGI resources in South Africa, the technology may be a viable environmental IPC solution for the COVID-19 period and beyond.

Objective. To monitor the number of bacterial colonies in the air of computed tomography (CT) room for COVID-19 using different disinfection methods and to identify the most effective method for disinfection and protection of equipment. Methods. Three methods for disinfection using ultraviolet germicidal irradiation (group A), plasma circulation air sterilizer (group B), and ultraviolet germicidal irradiation plus plasma circulation air sterilizer (group C) were utilized to sanitize the air in the CT room dedicated to COVID-19 cases. Single-factor ANOVA was used to evaluate and compare the disinfection effect of the three air disinfection methods; an air microbial sampler was used to sample and measure the number of bacteria in the air of the machine room. Results. The number of bacteria in the air immediately after disinfection was significantly lower than before disinfection ( p < 0.01 ). All three disinfection methods met the disinfection requirement. No significant differences in the number of air bacteria in the machine room immediately after disinfection were observed among the three methods ( p > 0.05 ). In addition, the effect of disinfection after 2 h was compared, and the number of bacteria in group C after 2 h was significantly lower than that in group A and group B. Conclusions. All three disinfection methods have significant disinfection effects. In addition, using ultraviolet disinfection lamps combined with a plasma air disinfection machine to sterilize the air in CT machine room has the best disinfection effect for the longest duration. Therefore, we recommend the combined disinfection method (ultraviolet disinfection lamps plus plasma air disinfection), as well as formulating relevant disinfection management norms, which should thus be the method to use during pandemics.

Purpose To investigate the feasibility and practicality of ultraviolet (UV) germicidal irradiation of the inner bore of a computed tomography (CT) gantry as a means of viral decontamination. Method A UV lamp (PADNUT 38 W, 253 nm UV‐C light tube) and UV‐C dosimeter (GENERAL UV‐C Digital Light Meter No. UV512C) were used to measure irradiance throughout the inner bore of a CT scanner gantry. Irradiance (units μW/cm2) was related to the time required to achieve 6‐log viral kill (10−6 survival fraction). Results A warm‐up time of ~120 s was required for the lamp to reach stable irradiance. Irradiance at the scan plane (z = 0 cm) of the CT scanner was 580.9 μW/cm2, reducing to ~350 μW/cm2 at z = ±20 cm toward the front or back of the gantry. The angular distribution of irradiation was uniform within 10% coefficient of variation. A conservative estimate suggests at least 6‐log kill (survival fraction ≤ 10−6) of viral RNA within ±20 cm of the scan plane with an irradiation time of 120 s from cold start. More conservatively, running the lamp for 180 s (3 min) or 300 s (5 min) from cold start is estimated to yield survival fraction <

BackgroundIn the context of the ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, the supply of personal protective equipment remains under severe strain. To address this issue, re-use of surgical face masks and filtering facepiece respirators has been recommended; prior decontamination is paramount to their re-use.AimWe aim to provide information on the effects of three decontamination procedures on porcine respiratory coronavirus (PRCV)-contaminated masks and respirators, presenting a stable model for infectious coronavirus decontamination of these typically single-use-only products.MethodsSurgical masks and filtering facepiece respirator coupons and straps were inoculated with infectious PRCV and submitted to three decontamination treatments, UV irradiation, vaporised H2O2, and dry heat treatment. Viruses were recovered from sample materials and viral titres were measured in swine testicle cells.FindingsUV irradiation, vaporised H2O2 and dry heat reduced infectious PRCV by more than three orders of magnitude on mask and respirator coupons and rendered it undetectable in all decontamination assays.ConclusionThis is the first description of stable disinfection of face masks and filtering facepiece respirators contaminated with an infectious SARS-CoV-2 surrogate using UV irradiation, vaporised H2O2 and dry heat treatment. The three methods permit demonstration of a loss of infectivity by more than three orders of magnitude of an infectious coronavirus in line with the FDA policy regarding face masks and respirators. It presents advantages of uncomplicated manipulation and utilisation in a BSL2 facility, therefore being easily adaptable to other respirator and mask types.

Ultraviolet germicidal irradiation (UVGI) N95 filtering facepiece respirator (FFR) treatment is considered an effective decontamination approach to address the supply shortage of N95 FFRs during the ongoing Covid-19 pandemic. In this study, we investigated the nanomechanical and topographic properties of filtration fibers that have been exposed to different doses of UVC radiation. UVC exposure was shown to decrease both Young’s modulus (E), hardness (H) and fiber width, as measured on individual polypropylene (PP) fibers. Our results also show that the PP microfiber layer loses its strength when N95 respirators are exposed to an accumulated UVC dose during the process of decontamination, and the PP fiber width also exhibits a logarithmic decrease during UVC exposure. The nanoscale measurement results on individual fibers suggest that maximum cycles of UVC disinfection treatment should be limited due to excessive accumulated dose, which has the potential to decrease the fiber breaking strength.

We outline a simple, low-cost design—both scalable and adaptable worldwide—to decontaminate filtering facepiece respirators (FFRs) using ultraviolet bulbs and supplies found in most hardware stores. The setup will help health care workers safely reuse FFRs in light of the shortages during the COVID-19 pandemic., Key Messages Ultraviolet germicidal irradiation (UVGI) systems can be used to decontaminate filtering facepiece respirators that are in short supply during the current COVID-19 pandemic, but are costly and scarce.Custom-built UVGI systems can be easily and affordably created using common items found in hardware stores and within research institutions.Health care workers and administrators should consider this setup as a cost-effective option to combat personal protective equipment (PPE) shortages during the current pandemic.Academic institutions should consider fostering collaborations with local health care institutions to provide idle resources to front line health care workers facing PPE shortages., As the current COVID-19 pandemic illustrates, not all hospitals and other patient care facilities are equipped with enough personal protective equipment to meet the demand in a crisis. Health care workers around the world use filtering facepiece respirators to protect themselves and their patients, yet during this global pandemic they are forced to reuse what are intended to be single-use masks. This poses a significant risk to these health care workers along with the people they are trying to protect. Ultraviolet germicidal irradiation (UVGI) has been validated previously as a method to effectively decontaminate these masks between use. However, not all facilities have access to the expensive commercial ultraviolet type C (UV-C) lamp decontamination equipment required for UVGI. UV-C bulbs are sitting idle in biosafety cabinets at universities and research facilities around the world that have been shuttered to slow the spread of COVID-19. These bulbs may also be available in existing medical centers where infectious diseases are commonly treated. We developed a method to modify existing light fixtures or create custom light fixtures that are compatible with new or existing UV-C bulbs. This system is scalable; can be created for less than US$50, on site and at the point of need; and leverages resources that are currently untapped and sitting unused in public and private research facilities during the pandemic. The freely accessible design can be easily modified for use around the world. Health care facilities can obtain this potentially lifesaving UVGI resource with minimal funds by collaborating with research facilities to obtain the UV-C meters and UV-C bulbs if they are unavailable from other sources. Although mask reuse is not ideal, we must do what we can in emergency situations to protect our health care workers responding to the pandemic and the communities they serve.

En este trabajo se presentan criterios que permiten estimar parámetros de desinfección mediante el uso de luz ultravioleta UV-C de onda corta, en agua, aire y superficies. Se indican métodos para evaluar la dosificación en función de la potencia de la lámpara empleada. Este tipo de estrategia permiten resultados de hasta 99.9% de desinfección, inactivando diferentes tipos de microorganismos. Estas referencias sirven de base para el diseño de dispositivos de utilidad en la presente emergencia por COVID-19, cuyo origen, al ser viral, es susceptible al mismo método de desinfección debido al proceso de dimerización del ADN, donde el daño producido en la estructura celular, afecta la capacidad de reproducción y de funcionalidad. Palabras Clave: luz UV-C o germicida, desinfección UV, dimerización del ADN. Referencias [1]R. Wallace, M. Ouellette and J. Jean, "Effect of UV‐C light or hydrogen peroxide wipes on the inactivation of methicillin resistant Staphylococcus aureus , Clostridium difficile spores and norovirus surrogate", Journal of Applied Microbiology, vol. 127, no. 2, pp. 586-597, 2019. [2]J. Vargas, "Efecto de la radiación gamma sobre las características físico - químicas, sensoriales y microbiológicas en páprika en polvo (Capsicum annuum L.)", Revista ECIPeru, pp. 68-71, 2019. [3]M. Ángeles García y P. Fernández, "Luz ultravioleta e inmunidad", Piel, vol. 21, no. 8, pp. 367-368, 2016. [4]W. Pachuau y R. Tiwari, "(Invited) Deep Ultraviolet Light Emitting Diodes: Physics, Performance, and Applications", ECS Meeting Abstracts, 2014. [5]W. Kowalski, Ultraviolet Germicidal Irradiation Handbook, 5th ed. Berlin: Springer Berlin, 2014, pp. 1-13. [6]W. Kowalski, Ultraviolet Germicidal Irradiation Handbook, 5th ed. Berlin: Springer Berlin, 2014, pp. 17-47. [7]"Germicidal Ultraviolet (GUV)", Media.ies.org, 2020. [En línea]. Disponible en: https://media.ies.org/docs/standards/IES%20CR-2-20-V1a-20200507.pdf. [Último acceso: 16 de junio de 2020]. [8]J. Bolton y C. Cotton, The ultraviolet disinfection handbook, 3rd ed. Denver, Colo.: American Water Works Association, 2008, pp. 13-33. [9]W. Kowalski, Ultraviolet Germicidal Irradiation Handbook, 5th ed. Berlin: Springer Berlin, 2014, pp. 8-9. [10]P. Aguirre, J. García y R. Mujeriego Sahuquillo, "Desinfección con cloro y luz UV en un proceso convencional de regeneración de agua", Ingeniería del agua, vol. 11, no. 1, p. 75, 2004.

Personal protective equipment (PPE) has been an invaluable yet limited resource when it comes to protecting healthcare workers against infection during the 2019 coronavirus (COVID-19) pandemic. In the US, N95 respirator supply chains are severely strained and conservation strategies are needed. A multidisciplinary team at the Washington University School of Medicine, Barnes Jewish Hospital, and BJC Healthcare was formed to implement a program to disinfect N95 respirators. The process described extends the life of N95 respirators using vaporized hydrogen peroxide (VHP) disinfection and allows healthcare workers to retain their own N95 respirator across a large metropolitan healthcare system.

The purpose of this investigation was to identify, synthesize, and compare all the current information on the efficacy of dental masks, emphasizing their use, types, and filters to prevent the spread and infection of COVID-19 and other infectious diseases. A bibliographic search of the main scientific databases was carried out using the words “masks, COVID-19, and dentistry.” Articles without language restriction up to May 31, 2020, were obtained. The types of masks, their half-life, method to use, sterilization, and proposed alternatives for dental masks were analyzed. Most of the articles refer to the use of N95 or FFP2 respirators presented as a strategy to extend the life of the masks and limited reuse. Regarding sterilization, most of the articles presented studies using ultraviolet germicidal irradiation as the sterilization method. Regarding respirator mask half-life, we recommend prolonged use, combined with a disposable surgical mask over the respirator mask. Finally, the use of N95 or FFP2 respirators are recommended as part of personal protective equipment for dental use.

In-duct ultraviolet germicidal irradiation systems are effective systems that are used in disinfection of pathogenic particles transported by air that moving through the ventilation systems. Proper...

OBJECTIVE To determine whether exposure to UV germicidal irradiation (UVGI) reduces concentrations of viable aerosolized microorganisms (attenuated strains of common veterinary pathogens) in a simulated heating, ventilation, and air conditioning (HVAC) system. SAMPLE 42 air samples seeded with bacteriophage MS2 or attenuated strains of Bordetella bronchiseptica, feline calicivirus, feline herpesvirus-1, canine parvovirus, or canine distemper virus (6/microorganism) or with no microorganisms added (6). PROCEDURES A simulated HVAC unit was built that included a nebulizer to aerosolize microorganisms suspended in phosphate-buffered water, a fan to produce airflow, 2 UVGI bulb systems, and an impinger for air sampling. Ten-minute trials (3 with UVGI, 3 without UVGI, and 1 negative control) were conducted for each microorganism. Impingers collected microorganisms into phosphate-buffered water for subsequent quantification with culture-based assays. Results for samples yielding no target microorganisms were recorded as the assay's lower limit of detection. Statistical analysis was not performed. RESULTS The UVGI treatment resulted in subjectively lower concentrations of viable MS2, B bronchiseptica, and canine distemper virus (arithmetic mean ± SD log10 microorganism reduction, 2.57 ± 0.47, ≥ 3.45 ± 0.24, and ≥ 1.50 ± 0.25, respectively) collected from air. Feline herpesvirus-1 was detected in only 1 sample without and no samples with UVGI treatment. Feline calicivirus and canine parvovirus were not detectable in any collected samples. CONCLUSIONS AND CLINICAL RELEVANCE Results for some surrogates of veterinary pathogens suggested a potential benefit to supplementing manual disinfection practices with UVGI-based air cleaning systems in animal care environments. Further research is needed to investigate the utility of UVGI in operating HVAC systems.

During global health emergencies such as the current COVID-19 pandemic, the decontamination of single-use personal protective equipment (PPE) becomes a necessary means to keep up with the growing demand from healthcare workers and patients alike. Many unverified methods are being considered, which can pose the risk of incomplete decontamination and lead to catastrophic results. Several factors come into play when determining the suitability of such methods including the quality of the decontamination technique, the targeted pathogen, cost, ease of installation and use, rate of sterilization, and the surface or material to be sterilized. The germicidal properties of ultraviolet-C are well known. This review will cover the most commonly described methods for the sterilization of N95 respirators, namely, ultraviolet germicidal irradiation, hydrogen peroxide vaporization, microwave-generated steaming, and dry heating. These techniques have been tested previously and have demonstrated efficacy in reducing or inactivating viral and bacterial pathogens, although testing against SARS-CoV-2 specifically has not been done. Moreover, it must be emphasized that proper disposal after a single use is still ideal under normal circumstances.

A link to the video summarizing the study may be found here: https://calhoun.nps.edu/handle/10945/68659. A poster describing the work may be found here: https://calhoun.nps.edu/handle/10945/70986. This thesis explores the feasibility of using ultraviolet germicidal irradiation (UVGI) to help clean the air aboard U.S. Navy ships. Recent airborne-related infections on naval vessels, including the COVID-19 outbreak aboard a United States aircraft carrier, highlight the need to improve disinfection techniques used aboard naval vessels. Application of 200-280 nm wavelength UVC light to the ship's heating, ventilation, air conditioning (HVAC) system in using specific exposure profiles makes inactivation and termination of airborne pathogens possible. Research has shown that UVGI is also successful at destroying biological warfare agents such as anthrax. Proper implementation of UVGI within a ship's ventilation system and in-room spaces can achieve high disinfection rates of airborne pathogens, reduce airborne-related illnesses, and increase operational availability. Commercial maritime employment of UVGI is also instructive. Recommendations include completing a multi-disciplinary design effort to install commercial-based prototypes on naval ships. Civilian, Department of the Navy Approved for public release. Distribution is unlimited.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is mainly transmitted by airborne droplets generated by infected individuals. Since this and many other pathogens are able to remain viable on inert surfaces for extended periods of time, contaminated surfaces play an important role in SARS-CoV-2 fomite transmission. Cosmetic products are destined to be applied on infection-sensitive sites, such as the lips and eyelids. Therefore, special biosafety precautions should be incorporated into the routine procedures of beauty parlors and shops. Indeed, innovative cosmetics companies are currently searching for disinfection protocols that ensure the customers’ safety in makeup testing. Here, we propose an ultraviolet germicidal irradiation (UVGI) strategy that can be used to reduce the odds of COVID-19 fomite transmission by makeup testers. It is well-known that UVGI effectively inactivates pathogens on flat surfaces and clear fluids. However, ultraviolet-C (UVC) radiation at 254 nm penetrates poorly in turbid and porous materials, such as makeup and lipstick formulations. Thus, we investigated the virucidal effect of UVGI against SARS-CoV-2 deposited on such substrates and compared their performance to that of flat polystyrene surfaces, used as controls. Concentrated infectious SARS-CoV-2 inoculum (106 PFU/mL) deposited on lipstick and makeup powder was completely inactivated (>5log10 reduction) following UVC exposures at 1,260 mJ/cm2, while flat plastic surfaces required 10 times less exposure (126 mJ/cm2) to reach the same microbicidal performance. We conclude that UVGI comprises an effective disinfection strategy to promote biosafety for cosmetics testers. However, appropriate UVC dosimetry must be implemented to overcome inefficiencies caused by the optical properties of turbid materials in lipsticks and makeup powders.

In the preparation and response to the COVID-19 pandemic, a sufficient supply of personal protective equipment (PPE), particularly the face mask, is essential. Shortage of PPE due to growing demand leaves health workers at significant risk as they fight this pandemic on the frontline. As a mitigation measure to overcome potential mask shortages, these masks could be decontaminated and prepared for reuse. This review explored past scientific research on various methods of decontamination of the N95-type respirators and their efficiency against the SARS-CoV-2 virus. Ultraviolet germicidal irradiation (UVGI) and hydrogen peroxide vapor (HPV) show great potential as an effective decontamination system. In addition, UVGI and HPV exhibit excellent effectiveness against the SARS-CoV-2 virus on the N95 respirator surfaces.

Respiratory viruses are capable of transmitting via an aerosol route. Emerging evidence suggests that SARS-CoV-2 which causes COVID-19 can be spread through airborne transmission, particularly in indoor environments with poor ventilation. Heating, ventilation, and air conditioning (HVAC) systems can play a role in mitigating airborne virus transmission. Ultraviolet germicidal irradiation (UVGI), a feature that can be incorporated into HVAC systems, can be used to impede the ability of viruses to replicate and infect a host. We conducted a systematic review of the scientific literature examining the effectiveness of HVAC design features in reducing virus transmission—here we report results for ultraviolet (UV) radiation. We followed international standards for conducting systematic reviews and developed an a priori protocol. We conducted a comprehensive search to January 2021 of published and grey literature using Ovid MEDLINE, Compendex, and Web of Science Core. Two reviewers were involved in study selection, data extraction, and risk of bias assessments. We presented study characteristics and results in evidence tables, and synthesized results across studies narratively. We identified 32 relevant studies published between 1936 and 2020. Research demonstrates that: viruses and bacteriophages are inactivated by UV radiation; increasing UV dose is associated with decreasing survival fraction of viruses and bacteriophages; increasing relative humidity is associated with decreasing susceptibility to UV radiation; UV dose and corresponding survival fraction are affected by airflow pattern, air changes per hour, and UV device location; and UV radiation is associated with decreased transmission in both animal and human studies. While UV radiation has been shown to be effective in inactivating viruses and reducing disease transmission, practical implementation of UVGI in HVAC systems needs to consider airflow patterns, air changes per hour, and UV device location. The majority of the scientific literature is comprised of experimental, laboratory-based studies. Further, a variety of viruses have been examined; however, there are few studies of coronaviruses and none to date of SARS-CoV-2. Future field studies of UVGI systems could address an existing research gap and provide important information on system performance in real-world situations, particularly in the context of the current COVID-19 pandemic. This comprehensive synthesis of the scientific evidence examining the impact of UV radiation on virus transmission can be used to guide implementation of systems to mitigate airborne spread and identify priorities for future research. Trial registration PROSPERO 2020 CRD42020193968.

Robots are being increasingly used in the fight against highly-infectious diseases such as Ebola, MERS, and SARS-CoV-2. Many of these robots use ultraviolet lights mounted on a mobile base to inactivate the pathogens. While the lights are generally effective at irradiating open spaces and walls, they are less effective when it comes to horizontal surfaces, because of the orientation of the light sources. This can be problematic for pathogens such as Ebola, where transmission via contaminated work surfaces, which are often horizontal, is a concern. In this paper, we describe the design, implementation, and testing of an ultraviolet light disinfection system implemented on a mobile manipulator robot designed to address the problem of horizontal surface disinfection. A human supervisor designates a surface for disinfection, the robot autonomously plans and executes an end-effector trajectory to disinfect the surface to the required certainty, and then displays the results for the supervisor to verify. We also provide some background information on Ultraviolet Germicidal Irradiation (UVGI) and describe how we constructed and validated models of ultraviolet radiation propagation and accumulation in our system. Finally, we describe our implementation on a Fetch mobile manipulation platform, and discuss how the practicalities of implementation on a real robot affect our models.

The use of ultraviolet germicidal irradiation (UVGI) to combat disease transmission has come into the international spotlight again because of the recent SARS-CoV-2 pandemic and ongoing outbreaks of MDROs (multidrug resistant organisms) in hospitals. Although the implementation of ultraviolet disinfection technology is widely employed in healthcare facilities and its effectiveness has been repeatedly demonstrated, the use of such technology in the commercial sector has been limited. Considering that most disease transmission occurs in commercial, public, and residential indoor environments as opposed to healthcare facilities, there is a need to understand whether ultraviolet (UV) disinfection technology can be effective for mitigating disease transmission in these environments. The results presented here demonstrate that the installation of fixed in-room UVGI air cleaners in commercial buildings, including restaurants and offices, can produce significant reductions in both airborne and surface borne bacterial contamination. Total airborne reductions after UV implementation at six separate commercial sites averaged 73% (p < 0.0001) with a range of 71-88%. Total non-high touch surface reductions after implementation averaged 55% (p < 0.0001) with a range of 28-88%. All reductions at the mitigated sites were statistically significant. The mean value of indoor airborne bacteria was 320 CFU/m3 before intervention and 76 CFU/m3 after. The mean value of indoor non-high touch surface borne bacteria was 131 CFU/plate before intervention and 47 CFU/plate after. All test locations and controls had their required pandemic cleaning procedures in place for pre- and post-sampling events. Outdoor levels of airborne bacteria were monitored and there was no significant correlation between the levels of airborne bacteria in the outside air as opposed to the indoor air. Rooms with fixed in-room UVGI air cleaners installed had significant CFU reductions on local surface contamination, which is a novel and important finding. Installation of fixed in-room UVGI air cleaners in commercial buildings will decontaminate the indoor environment and reduce hazardous exposure to human pathogens.

During the coronavirus disease 2019 (COVID-19) pandemic, the use of ultraviolet (UV) rays to disinfect skin areas, clothes and other objects at the entry/exit points of public spaces has been widely discussed by stakeholders. While ultraviolet germicidal irradiation (UVGI) has been shown to effectively inactivate coronaviruses, including severe acute respiratory syndrome coronavirus (SARS-CoV)-1 and Middle East respiratory syndrome coronavirus (MERS-CoV), no specific evidence proves that it effectively inactivates the new SARS-CoV-2 virus that causes COVID-19. Because UV rays damage human tissue, UVGI should be used with caution and not directly on human skin. Various guidelines recommend that UVGI should not be used as a sole agent for disinfecting surfaces or objects but as an adjunct to the latest standard disinfecting procedures.