Fast inactivation of coronavirus in filtering-facepiece respirators in a reflective cylindrical UV-C chamber.

Objective: We report on the development and characterization of a UV-C (λ  =  200 - 280 nm, λpeak = 254 nm) chamber designed for the rapid disinfection of N95 class filtering-facepiece respirators contaminated with SARS-CoV-2 coronaviruses. The device was evaluated against Betacoronavirus strain MHV-3 and its virucidal capacity was evaluated as a function of different applied UV-C doses (UV-C exposure times of 60 s, 120 s, 180 s, and 240 s) using two types of respirators geometry (shell and two-panel shapes, 3M 8801 H and 9920 H, respectively), at eight points of the respirators. Background: Most chemical disinfection methods are not recommended for N95 masks. UV-C light provided by UVGI lamps (254 nm) is an effective physical agent against viruses and bacteria due to direct photochemical harming effect on DNA/RNA, and can provide rapid disinfection for personal protective equipment such as N95/PFF2 masks. Results: The device reached a mean elimination rate of 99.9999% of MHV-3 inoculated into all the assessed different points on the tested PFF2 respirator models in a UV-C cycle of just 60 s. Statistical analysis performed through Person´s chi-square test showed no correlation between the viral infectivity reduction and the viral inoculation point (p = 0.512) and the tested respirator models (p = 0.556). However, a correlation was found between the exposure time and the viral infectivity reduction (p = 0.000*), between UV-C and no UV-C exposure. All the tested UV-C exposure times (60 s, 120 s, 180 s, and 240 s) provided the same reduction in infection rates. Therefore, 60 s was confirmed as the minimum exposure time to achieve a 99.9999% or 6 Log reduction in MHV-3 coronavirus infection rates in the PFF2 samples tested in the device. Conclusions: We conclude that the assessed UV-C chamber for the inactivation of MHV-3 coronavirus in N95/PFF2 standard masks can be a promising tool for effective and rapid disinfection of coronaviruses, including SARS-CoV-2 virus.

Rapid SARS-CoV-2 disinfection on distant surfaces with UV-C: The inactivation is affected by the type of material.

SARS-CoV-2 is responsible for the COVID-19 pandemic, which has caused almost 570 million infections and over six million deaths worldwide. To help curb its spread, solutions using ultraviolet light (UV) for quick virus inactivation inside buildings without human intervention could be very useful to reduce chances of contagion. The UV dose must be sufficient to inactivate the virus considering the different materials in the room, but it should not be too high, not to degrade the environment. In the present study, we have analyzed the ability of a 254 nm wavelength UV-C lamp to inactivate dried samples of SARS-CoV-2 exposed at a distance of two meters, simulating a full-scale scenario. Our results showed that virus inactivation was extremely efficient in most tested materials, which included plastic, metal, wood, and textile, with a UV-C exposure of only 42 s (equivalent to 10 mJ/cm2). However, porous materials like medium density fibreboard, were hard to decontaminate, indicating that they should be avoided in hospital rooms and public places.

GLAMP: Low-cost ozone and UV-C light-emitting portable device for disinfection of environments

With the Covid-19 pandemic outbreak, the demand for high-quality, low-cost, and safe use equipment for disinfecting hospitals, offices, schools, restaurants, supermarkets, etc., is growing. Although for years it has been known that the ozone produced by the UV-C technology irradiation is highly germicidal, its commercial use for enclosed spaces disinfection as a source of bacteria and viruses' infections is recent. Motivated by the above, this article introduces a low-cost ozone and UV-C light-emission portable device to satisfy the growing demand for disinfection of enclosed and unoccupied spaces. gLAMP, the proposal of this work, offers users a safe-to-use disinfection process by incorporating a pair of sensors into the design to measure air quality, keep users out of the risk area and streamline the ozone diffusion and ventilation processes in the area to be disinfected. As well as a mobile application to control and monitor the equipment and disinfection service remotely. Preliminary tests were carried out to verify the functionality of gLAMP and its potential commercial impact. © 2022 ACM.

Prompt Inactivation of Coronavirus Using a 280 nm Light-Emitting Diode Cluster Device.

Objective: We report on the development and characterization of a UV-C light-emitting diode (LED) 280 nm cluster prototype device designed for the rapid disinfection of SARS-CoV-2 coronaviruses. The device was evaluated against the Betacoronavirus mouse hepatitis virus-3 strain, and its virucidal capacity was probed as a function of different applied UV-C doses versus different situations concerning irradiation distances. Background: UV-C LEDs are light emitters that offer advantages over low-pressure mercury lamps, such as quasimonochromaticity, lower electrical power consumption, instant on/off with the instant full-power operation, unlimited on/off cycles for disinfection schemes, and a much longer lifetime operation, in addition to portability aspects, as well as UV-C LEDs do not contain heavy metal in its composition such as mercury, found in ultraviolet germicidal irradiation (UVGI) lamps. Results: This novel device reached a 99.999% elimination rate at a distance of 9 cm at all the tested irradiation times (dose dependence), demonstrating that it took only 30 sec to achieve this inactivation rate. Its virucidal effectivity in rapid virus inactivation was demonstrated. Conclusions: We conclude that the HHUVCS cluster device (λp = 280 nm) provides a rapid virucidal effect against the SARS-CoV-2 coronavirus. The current research should encourage further advances in UV-C LED-based devices designed for the inactivation of SARS-CoV-2 virus on surfaces, in air, and in liquids.

Evaluation of UV-C Radiation Efficiency in the Decontamination of Inanimate Surfaces and Personal Protective Equipment Contaminated with Phage ϕ6.

To help halt the global spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), appropriate disinfection techniques are required. Over the last years, the interest in Ultraviolet-C (UV-C) radiation as a method to disinfect inanimate surfaces and personal protective equipment (PPE) has increased, mainly to efficiently disinfect and prevent SARS-CoV-2 from spreading and allow for the safe reuse of said equipment. The bacteriophage ϕ6 (or simply phage ϕ6) is an RNA virus with a phospholipid envelope and is commonly used in environmental studies as a surrogate for human RNA-enveloped viruses, including SARS-CoV-2. The present study investigated the use of two new UV irradiation systems ((2)2.4W and (8)5.5W)) constituted by conventional mercury UV-C lamps with a strong emission peak at ~254 nm to potentially inactivate phage ϕ6 on different surfaces (glass, plastic, stainless steel, and wood) and personal protective equipment, PPE, (surgical and filtering facepiece 2, FFP2, masks, a clear acetate visor, and disposable protective clothing). The results showed that both UV-C systems were effective in inactivating phage ϕ6, but the UV-C sterilizing chamber (8)5.5W had the best disinfection performance on the tested surfaces. The inactivation effectiveness is material-dependent on all surfaces, reaching the detection limit of the method at different times (between 60 and 240 s of irradiation). The glass surface needed less time to reduce the virus (30 s) when compared with plastic, stainless, and wood surfaces (60 s). The virus inactivation was more effective in the disposable surgical and FFP2 masks (60 and 120 s, respectively) than in the disposable vest and clear acetate visor (240 s). Overall, this study suggests that UV-C lamps with peak emission at ~254 nm could provide rapid, efficient, and sustainable sanitization procedures to different materials and surfaces. However, dosage and irradiation time are important parameters to be considered during their implementation as a tool in the fight against human coronaviruses, namely against SARS-CoV-2.

Study of Viral Photoinactivation by UV-C Light and Photosensitizer Using a Pseudotyped Model.

Different light-based strategies have been investigated to inactivate viruses. Herein, we developed an HIV-based pseudotyped model of SARS-CoV-2 (SC2) to study the mechanisms of virus inactivation by using two different strategies; photoinactivation (PI) by UV-C light and photodynamic inactivation (PDI) by Photodithazine photosensitizer (PDZ). We used two pseudoviral particles harboring the Luciferase-IRES-ZsGreen reporter gene with either a SC2 spike on the membrane or without a spike as a naked control pseudovirus. The mechanism of viral inactivation by UV-C and PDZ-based PDI were studied via biochemical characterizations and quantitative PCR on four levels; free-cell viral damage; viral cell entry; DNA integration; and expression of reporter genes. Both UV-C and PDZ treatments could destroy single stranded RNA (ssRNA) and the spike protein of the virus, with different ratios. However, the virus was still capable of binding and entering into the HEK 293T cells expressing angiotensin-converting enzyme 2 (ACE-2). A dose-dependent manner of UV-C irradiation mostly damages the ssRNA, while PDZ-based PDI mostly destroys the spike and viral membrane in concentration and dose-dependent manners. We observed that the cells infected by the virus and treated with either UV-C or PDZ-based PDI could not express the luciferase reporter gene, signifying the viral inactivation, despite the presence of RNA and DNA intact genes.

Evaluation of a portable Ultraviolet C (UV-C) device for hospital surface decontamination.

BACKGROUND: Surface decontamination of hospital environments is essential to ensure the safety of health professionals and patients. This process is usually performed through active chemicals substances with high toxicity, and new decontamination technologies that do not leave residues have been currently used, such as UV-C light. Thus, the objective of the present study is to evaluate the effectiveness of a portable UV-C light device on the viability of standard pathogenic strains and other microorganisms isolated from different surfaces of a public health hospital. METHODS: In vitro decontamination was performed by applying Biosept Home© UV-C to Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica and Candida albicans. In real conditions, the application was made on different surfaces of a hospital. The device used in the experiment haa a 254 nm UV-C light and a radiation intensity of 45.6 mW/cm2 over a distance of 1 cm from the surfaces. The light dose was 0.912 J/cm2 for 20 s of application in both conditions (in vitro and hospital). RESULTS: After in vitro decontamination with UV-C light no bacterial growth was observed, demonstrating 100 % of bacterial inactivation under the conditions tested. Additionally, there was a reduction of approximately 4 logs for the yeast C. albicans. In all hospital surfaces, the number of colonies of microorganisms was significantly reduced after the procedure. CONCLUSION: The results suggest that Biosept Home© UV-C is efficient and constitutes a promosing intervention for disinfection protocols in hospitals and clinics.

Transmission routes, preventive measures and control strategies of SARS-CoV-2 in the food factory.

SARS-CoV-2 virus represents a health threat in food factories. This infectious virus is transmitted by direct contact and indirectly via airborne route, whereas contamination through inanimate objects/surfaces/equipment is uncertain. To limit the potential spread of the pathogen in the food industry, close working between individuals should be avoided and both personal and respiratory hygiene activities should be enforced. Despite the high infectivity, SARS-CoV-2, being an enveloped virus with a fragile lipid envelop, is sensitive to biocidal products and sanitizers commonly used in the food factory. In the context of the building design, interventions that promote healthy air quality should be adopted, especially in food areas with high-occupancy rates for prolonged times, to help minimize the potential exposure to airborne SARS-CoV-2. Air ventilation and filtration provided by heating, ventilation and air conditioning systems, are effective and easy-to-organize tools to reduce the risk of transmission through the air. In addition to conventional sanitation protocols, aerosolization of hydrogen peroxide, UV-C irradiation or in-situ ozone generation are complementary techniques for an effective virucidal treatment of the air.

Biosafety Level 2 cabinet UV-C light exposure of sports antidoping human urine samples does not affect the stability of selected prohibited substances.

The current study examined the stability of several antidoping prohibited substances analytes in urine after 15-min exposure to UV-C light in a Biosafety Level 2 cabinet. The urine matrices were exposed within the original antidoping bottles with the aim to destroy DNA/RNA and possible SARS CoV-2. The analytes small molecules Phase I and Phase II metabolites and peptides, in total 444, endogenous, internal standards, and prohibited substances, pH, and specific gravity in urine were studied. The accredited analytical methods were used by Anti-Doping Laboratory Qatar for the comparison of data of the same urine samples analyzed with and without UV-C exposure. In the study conditions, no problems of stability were detected in the substances spiked in the urine samples exposed in the UV-C irradiation.