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2.
Opt Mater (Amst) ; 140: 113866, 2023 Jun.
Article in English | MEDLINE | ID: covidwho-2315983

ABSTRACT

Disinfection with far UV-C radiation (<230 nm) is an effective method to inactivate harmful microorganisms like the SARS-CoV2 virus. Due to the stronger absorption than regular UV-C radiation (254 nm) and hence limited penetration into human tissues, it has the promise of enabling disinfection in occupied spaces. The best far-UV sources so far are discharge lamps based on the KrCl* excimer discharge peaking at 222 nm, however they produce longer wavelength radiation as a by-product. In current KrCl* excimer lamps usually a dichroic filter is used to suppress these undesired longer wavelengths. A phosphor-based filter is an alternative which is cheaper and easier to apply. This paper describes the results of our exploration of this opportunity. Various compounds were synthesized and characterized to find a replacement for the dichroic filter. It was found that Bi3+-doped ortho-borates with the pseudo-vaterite crystal structure exhibit the best absorption spectrum i.e. high transmission around 222 nm and strong absorption in the 235-280 nm range. Y0.24Lu0.75Bi0.01BO3 showed the best absorption spectrum in the UV-C. To suppress the unwanted Bi3+ emission (UV-B), the excitation energy can be transferred to a co-dopant. Ho3+ turned out to be the best co-dopant, and Ho0.24Lu0.75Bi0.01BO3 appeared to be the best overall candidate for the phosphor filter material. A suitable formulation for a coating suspension containing this material was found, and quite homogeneous coatings were achieved. The efficiency of these filter layers was investigated and the results in terms of exposure limit increase i.e. gain factor vs. no filter were compared with the dichroic filter. We achieved a gain factor for the Ho3+ containing sample of up to 2.33, i.e. not as good as that of the dichroic filter (∼4.6), but a very relevant improvement, making Ho0.24Lu0.75Bi0.01BO3 an interesting material for a cost-effective filter for KrCl* far UV-C lamps.

3.
Food Environ Virol ; 2023 May 04.
Article in English | MEDLINE | ID: covidwho-2315543

ABSTRACT

Monitoring the circulation of enteric viruses in environmental wastewater is a valuable tool for preventing the emergence of waterborne and food-borne diseases in humans. The detection of viruses was performed in five Tunisian wastewater treatment plants, three located in the Grand Tunis City (WWTP 1, WWTP 2, WWTP 3) and two in the Sahel of Tunisia (WWTP 4, WWTP 4), known as very developed and crowded zones, to assess the effectiveness of three biological wastewater treatment procedures namely natural oxidizing lagoons, rotating biodisks procedure, activated sludge procedure, and one tertiary sewage treatment using UV-C254 reactor for this enteric viruses' removal. Thus, 242 sewage samples were collected between June 2019 and May 2020 from different lines of wastewater treatment procedures implemented in the five wastewater treatment plants investigated. SARS-CoV-2 was analyzed using real-time multiplex reverse-transcription polymerase chain reaction (multiplex real-time RT-PCR) and enteroviruses using reverse-transcription polymerase chain reaction (RT-PCR). The enteroviruses detection showed 93% and 73% respective high frequencies only in the two WWTPs of the Grand Tunis (WWTP 1 and WWTP 2). SARS-CoV-2 was detected in 58% of the all wastewater samples collected from the five studied WWTPs with a respective dominance of N gene (47%), S gene (42%), RdRp gene (42%) and at last E gene (20%). These enteroviruses and SARS-CoV-2 detection were revealed in all steps of the wastewater treatment procedures, so poor virological quality is found at the exit of each biological and tertiary step of treatment investigated. For the first time in Tunisia, these results highlighted the enterovirus and SARS-CoV-2 detection with high rates, and the ineffectiveness of the biological and UV-C254 treatment implemented to remove these viruses. The preliminary results of SARS-CoV-2 circulation in Tunisian wastewater confirmed the wide positivity rate underlined by other works worldwide and allowed showing a move towards integrating wastewater as a way for this virus to spread in different areas and environments. So, this last result about SARS-CoV-2 circulation allowed us to caution about the strong probability of diffusion of this hazardous virus through water and sewage; despite its enveloped character and nature, as a labile and sensitive virus in these environments. Thus, establishing a national surveillance strategy is needed to improve the sanitary quality of treated wastewater and prevent public health problems related to these viruses in treated wastewater.

4.
Pathogens ; 11(1)2022 Jan 10.
Article in English | MEDLINE | ID: covidwho-2315199

ABSTRACT

The arrival of SARS-CoV-2 to Aotearoa/New Zealand in February 2020 triggered a massive response at multiple levels. Procurement and sustainability of medical supplies to hospitals and clinics during the then upcoming COVID-19 pandemic was one of the top priorities. Continuing access to new personal protective equipment (PPE) was not guaranteed; thus, disinfecting and reusing PPE was considered as a potential alternative. Here, we describe part of a local program intended to test and implement a system to disinfect PPE for potential reuse in New Zealand. We used filtering facepiece respirator (FFR) coupons inoculated with SARS-CoV-2 or clinically relevant multidrug-resistant pathogens (Acinetobacter baumannii Ab5075, methicillin-resistant Staphylococcus aureus USA300 LAC and cystic-fibrosis isolate Pseudomonas aeruginosa LESB58), to evaluate the potential use of ultraviolet-C germicidal irradiation (UV-C) or dry heat treatment to disinfect PPE. An applied UV-C dose of 1000 mJ/cm2 was sufficient to completely inactivate high doses of SARS-CoV-2; however, irregularities in the FFR coupons hindered the efficacy of UV-C to fully inactivate the virus, even at higher UV-C doses (2000 mJ/cm2). Conversely, incubating contaminated FFR coupons at 65 °C for 30 min or 70 °C for 15 min, was sufficient to block SARS-CoV-2 replication, even in the presence of mucin or a soil load (mimicking salivary or respiratory secretions, respectively). Dry heat (90 min at 75 °C to 80 °C) effectively killed 106 planktonic bacteria; however, even extending the incubation time up to two hours at 80 °C did not completely kill bacteria when grown in colony biofilms. Importantly, we also showed that FFR material can harbor replication-competent SARS-CoV-2 for up to 35 days at room temperature in the presence of a soil load. We are currently using these findings to optimize and establish a robust process for decontaminating, reusing, and reducing wastage of PPE in New Zealand.

5.
Polymers (Basel) ; 15(8)2023 Apr 21.
Article in English | MEDLINE | ID: covidwho-2291212

ABSTRACT

During the initial stages of the COVID-19 pandemic, healthcare facilities experienced severe shortages of personal protective equipment (PPE) and other medical supplies. Employing 3D printing to rapidly fabricate functional parts and equipment was one of the emergency solutions used to tackle these shortages. Using ultraviolet light in the UV-C band (wavelengths of 200 nm to 280 nm) might prove useful in sterilizing 3D printed parts, enabling their reusability. Most polymers, however, degrade under UV-C radiation, so it becomes necessary to determine what 3D printing materials can withstand the conditions found during medical equipment sterilization with UV-C. This paper analyzes the effect of accelerated aging through prolonged exposure to UV-C on the mechanical properties of parts 3D printed from a polycarbonate and acrylonitrile butadiene styrene polymer (ABS-PC). Samples 3D printed using a material extrusion process (MEX) went through a 24-h UV-C exposure aging cycle and then were tested versus a control group for changes in tensile strength, compressive strength and some selected material creep characteristics. Testing showed minimal mechanical property degradation following the irradiation procedure, with tensile strength being statistically the same for irradiated parts as those in the control group. Irradiated parts showed small losses in stiffness (5.2%) and compressive strength (6.5%). Scanning electron microscopy (SEM) was employed in order to assess if any changes occurred in the material structure.

6.
International Journal on Advanced Science, Engineering and Information Technology ; 13(1):276-282, 2023.
Article in English | Scopus | ID: covidwho-2279779

ABSTRACT

Airborne microorganisms must be controlled, especially during the COVID-19 pandemic, to prevent infectious diseases. This research was conducted to prepare a clean room and eliminate infectious pathogens. This study studied a 36-watt UV C commercial lamp to examine its effectiveness in controlling airborne microorganisms in rooms at Universitas Indonesia. The germicide effect of lamp (100 mJ/cm2) predicted by the UV-C test card could be achieved at a distance of 2 to 3 meter after exposure for 60 minutes. UVC's effectiveness as a germicide was also tested on bacteria, yeast, and mold. No germicides were observed in A. parasiticus and C. lunata after being exposed to the UV-C light at 1 to 2 meters distance for 60 minutes. The germicides UV-C lamps were also applied in examined rooms. Active and passive sampling methods measured airborne microorganisms before and after the treatment of UV-C lamp. The lowest germicide effect of UV-C lamp was 37.66% in the collaboration laboratory, and the highest was 86.12% obtained in seminar room at Department of Biology. Many factors, such as the type of group of microorganisms, air circulation, and equipment in the room, influence the germicide effect of UV-C lamp. Based on existing microorganism populations, the examined indoor air has good quality under 1,000 CFU/m3 © IJASEIT is licensed under a Creative Commons Attribution-Share Alike 4.0 International License

7.
3rd IEEE International Conference on Computing, Communication, and Intelligent Systems, ICCCIS 2022 ; : 372-376, 2022.
Article in English | Scopus | ID: covidwho-2279318

ABSTRACT

SARS-CoV-2 started a global epidemic that resulted in COVID-19, a real infectious disease that disrupted regular living all over the world. Sterilizing our hands is crucial since the virus and other diseases are spread by touching contaminated surfaces. In this manuscript, a prototype for low-cost sterilisation is created that uses an IR thermal sensor to measure temperature and UV C light rays to disinfect our hands. Numerous bacteria are affected throughout the sanitization process, which has a number of advantages over chemical-based sanitization techniques. In contrast to relevant, it is also easy to customise. There are proprietary devices that can be purchased commercially. This gadget is an excellent illustration of open-source technology. automatic, quick, and safe hand sanitising device. © 2022 IEEE.

8.
Appl Biosaf ; 28(1): 1-10, 2023 Mar 01.
Article in English | MEDLINE | ID: covidwho-2252031

ABSTRACT

Introduction: The widespread transmission of the SARS-CoV-2 virus has increased scientific and societal interest in air cleaning technologies, and their potential to mitigate the airborne spread of microorganisms. Here we evaluate room scale use of five mobile air cleaning devices. Methods: A selection of air cleaners, containing high efficiency filtration, was tested using an airborne bacteriophage challenge. Assessments of bioaerosol removal efficacy were undertaken using a decay measurement approach over 3 h, with air cleaner performance compared with bioaerosol decay rate without an air cleaner in the sealed test room. Evidence of chemical by-product emission was also checked, as were total particle counts. Results: Bioaerosol reduction, exceeding natural decay, was observed for all air cleaners. Reductions ranged between devices from <2-log per m3 room air for the least effective, to a >5-log reduction for the most efficacious systems. One system generated detectable ozone within the sealed test room, but ozone was undetectable when the system was run in a normally ventilated room. Total particulate air removal trends aligned with measured airborne bacteriophage decline. Discussion: Air cleaner performance differed, and this could relate to individual air cleaner flow specifications as well as test room conditions, such as air mixing during testing. However, measurable reductions in bioaerosols, beyond natural airborne decay rate, were observed. Conclusion: Under the described test conditions, air cleaners containing high efficiency filtration significantly reduced bioaerosol levels. The best performing air cleaners could be investigated further with improved assay sensitivity, to enable measurement of lower residual levels of bioaerosols.

9.
Critical Reviews in Environmental Science and Technology ; 53(6):733-753, 2023.
Article in English | Scopus | ID: covidwho-2239235

ABSTRACT

Far UV-C, informally defined as electromagnetic radiation with wavelengths between 200 and 230 nm, has characteristics that are well-suited to control of airborne pathogens. Specifically, Far UV-C has been shown to be highly effective for inactivation of airborne pathogens;yet this same radiation has minimal potential to cause damage to human skin and eye tissues. Critically, unlike UV-B, Far UV-C radiation does not substantially penetrate the dead cell layer of skin (stratum corneum) and does not reach germinative cells in the basal layer. Similarly, Far UV-C radiation does not substantially penetrate through corneal epithelium of the eye, thereby preventing exposure of germinative cells within the eye. The most common source of Far UV-C radiation is the krypton chloride excimer (KrCl*) lamp, which has a primary emission centered at 222 nm. Ozone production from KrCl* lamps is modest, such that control of indoor ozone from these systems can be accomplished easily using conventional ventilation systems. This set of characteristics offers the potential for Far UV-C devices to be used in occupied spaces, thereby allowing for improved effectiveness for inactivation of airborne pathogens, including those that are responsible for COVID-19. © 2022 The Author(s). Published with license by Taylor & Francis Group, LLC.

10.
Gondwana Res ; 2022 Aug 02.
Article in English | MEDLINE | ID: covidwho-2232142

ABSTRACT

The high rate of transmission of the COVID-19 virus has brought various types of disinfection techniques, for instance, hydrogen peroxide vaporization, microwave generating steam, UV radiation, and dry heating, etc. to prevent the further transmission of the virus. The chemical-based techniques are predominantly used for sanitization of hands, buildings, hospitals, etc. However, these chemicals may affect the health of humans and the environment in unexplored aspects. Furthermore, the UV lamp-based radiation sanitization technique had been applied but has not gained larger acceptability owing to its limitation to penetrate different materials. Therefore, the optical properties of materials are especially important for the utilization of UV light on such disinfection applications. The germicidal or microorganism inactivation application of UV-C has only been in-use in a closed chamber, due to its harmful effect on human skin and the eye. However, it is essential to optimize UV for its use in an open environment for a larger benefit to mitigate the virus spread. In view of this, far UV-C (222nm) based technology has emerged as a potential option for the sanitization in open areas and degradation of microorganisms present in aerosol during the working conditions. Hence, in the present review article, efforts have been made to evaluate the technical aspects of UV (under the different spectrum and wavelength ranges) and the control of COVID 19 virus spread in the atmosphere including the possibilities of the human body sanitization in working condition.

11.
J Hosp Infect ; 132: 85-92, 2023 Feb.
Article in English | MEDLINE | ID: covidwho-2229414

ABSTRACT

Ultraviolet (UV)-C light for disinfection has experienced a surge in popularity since the outbreak of COVID-19. Currently, many different UV-C systems, with varied properties that impact disinfection performance, are available on the market. Therefore this review aims to bundle the available information on UV-C disinfection to obtain an overview of its advantages, disadvantages, and performance-influencing parameters. A literature search was performed using the snowball search method in Google Scholar and PubMed with the following keywords: UV-C disinfection, UV-C dose, UV-C light source, UV-C repair mechanism, UV-C photoreactivation, and UV-C disinfection standards. The main parameters of UV-C disinfection are wavelength, dose, relative humidity, and temperature. There is no consensus about their optimal values, but, in general, light at a high dose and a spectrum of wavelengths containing 260 nm is preferred in an environment at room temperature with low relative humidity. This light can be generated by mercury-vapour, light-emitting diode (LED), pulsed-xenon, or excimer lamps. Multiple factors are detrimental to disinfection performance such as shadowing, a rough surface topography, a high level of contamination, repair mechanisms, and the lack of standardization. Also, there are health and safety risks associated with the UV-C technology when used in the proximity of people. UV-C disinfection systems have promising features and the potential to improve in the future. However, clarifications surrounding the different parameters influencing the technologies' effectiveness in hospital environment are needed. Therefore UV-C disinfection should currently be considered for low-level rather than high-level disinfection.


Subject(s)
COVID-19 , Humans , COVID-19/prevention & control , Ultraviolet Rays , Hospitals , Disinfection/methods , Temperature
12.
J Hosp Infect ; 135: 11-17, 2023 May.
Article in English | MEDLINE | ID: covidwho-2220982

ABSTRACT

BACKGROUND: Ultraviolet (UV)-light-emitting diodes (UV-LEDs) are energy efficient and of special interest for the inactivation of micro-organisms. In the context of the coronavirus disease 2019 pandemic, novel UV technologies can offer a powerful alternative for effective infection prevention and control. METHODS: This study assessed the antimicrobial efficacy of UV-C LEDs on Escherichia coli, Pseudomonas fluorescens and Listeria innocua, as well as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), human immunodeficiency virus-1 (HIV-1) and murine norovirus (MNV), dried on inanimate surfaces, based on European Standard EN 17272. RESULTS: This study found 90% inactivation rates for the tested bacteria at mean UV-C doses, averaged over all three investigated UV-C wavelengths, of 1.7 mJ/cm2 for E. coli, 1.9 mJ/cm2 for P. fluorescens and 1.5 mJ/cm2 for L. innocua. For the tested viruses, UV doses <15 mJ/cm2 resulted in 90% inactivation at wavelengths of 255 and 265 nm. Exposure of viruses to longer UV wavelengths, such as 275 and 285 nm, required much higher doses (up to 120 mJ/cm2) for inactivation. Regarding inactivation, non-enveloped MNV required much higher UV doses for all tested wavelengths compared with SARS-CoV-2 or HIV-1. CONCLUSION: Overall, the results support the use of LEDs emitting at shorter wavelengths of the UV-C spectrum to inactivate bacteria as well as enveloped and non-enveloped viruses by exposure to the appropriate UV dose. However, low availability and excessive production costs of shortwave UV-C LEDs restricts implementation at present, and supports the use of longwave UV-C LEDs in combination with higher irradiation doses.


Subject(s)
Anti-Infective Agents , COVID-19 , Norovirus , Viruses , Humans , Animals , Mice , Escherichia coli , SARS-CoV-2 , Ultraviolet Rays , Bacteria , Disinfection/methods , Virus Inactivation
13.
2nd IEEE Mysore Sub Section International Conference, MysuruCon 2022 ; 2022.
Article in English | Scopus | ID: covidwho-2192041

ABSTRACT

The COVID-19 pandemic demanded innovative approaches to handle the situation around the globe. The Coronavirus challenged the effectiveness and practice of conventional surface disinfection methods. Existing disinfection methods rely on the manual administration of disinfectants. They are time-consuming, costly, and subject to human error. The paper proposes the implementation of an Ultraviolet Disinfection module that can be attached to any autonomous mobile robot. The autonomous Ultraviolet-C (UV-C) disinfection robot helps the user disinfect the premise without human intervention. The proposed system ensures proper disinfection by discovering near-optimal paths through the environment in minimum time. © 2022 IEEE.

14.
6th International Conference on Advanced Production and Industrial Engineering , ICAPIE 2021 ; : 261-272, 2023.
Article in English | Scopus | ID: covidwho-2173870

ABSTRACT

Rising air pollution is a cause of concern throughout the world. With rapid industrialization, growth of transportation industry, increasing construction activities, all has taken a toll on the air quality. The air quality in most parts of our country remains poor to moderately pollute for maximum part of the year. P.M. 2.5, P.M. 10, NOx, and SOx are the primary pollutants. Along with the poor quality of air, COVID-19 has added to the misery by affecting the respiratory tract and further worsening the condition of a patient. Through this project, we aim to build a economical solar powered air purifier that can be installed in each and every household as well as outdoors, catering to the air quality indoors, and contributing in purification of the air in the surrounding environment. The air purifier would be capable of providing air filtration as well as sterilization be powered by solar energy and be available at an affordable price. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

15.
Adv Eng Softw ; 175: 103330, 2023 Jan.
Article in English | MEDLINE | ID: covidwho-2122264

ABSTRACT

The COVID-19 pandemic made robot manufacturers explore the idea of combining mobile robotics with UV-C light to automate the disinfection processes. But performing this process in an optimum way introduces some challenges: on the one hand, it is necessary to guarantee that all surfaces receive the radiation level to ensure the disinfection; at the same time, it is necessary to minimize the radiation dose to avoid the damage of the environment. In this work, both challenges are addressed with the design of a complete coverage path planning (CCPP) algorithm. To do it, a novel architecture that combines the glasius bio-inspired neural network (GBNN), a motion strategy, an UV-C estimator, a speed controller, and a pure pursuit controller have been designed. One of the main issues in CCPP is the deadlocks. In this application they may cause a loss of the operation, lack of regularity and high peaks in the radiation dose map, and in the worst case, they can make the robot to get stuck and not complete the disinfection process. To tackle this problem, in this work we propose a preventive deadlock processing algorithm (PDPA) and an escape route generator algorithm (ERGA). Simulation results show how the application of PDPA and the ERGA allow to complete complex maps in an efficient way where the application of GBNN is not enough. Indeed, a 58% more of covered surface is observed. Furthermore, two different motion strategies have been compared: boustrophedon and spiral motion, to check its influence on the performance of the robot navigation.

16.
J Photochem Photobiol ; 12: 100151, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-2120218

ABSTRACT

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.

17.
2nd International Congress on Advances in Mechanical and Systems Engineering, CAMSE 2021 ; : 157-164, 2023.
Article in English | Scopus | ID: covidwho-2059746

ABSTRACT

Society is under tremendous tension and pressure due to the Coronavirus (COVID-19) pandemic. Coronavirus pandemic-2019 is a critical health emergency with respect to the international concern. Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-1) disease first came in 2002 and then Middle East Respiratory Syndrome Coronavirus (MERS-CoV) affects us in 2012. SARS-CoV-2 is the third coronavirus to emerge in the past two decades, which are acting as a serious warning to humans. These pandemic presents major challenges to scientist and international medical agencies to save the earth by this global life-threatening pandemic. Fighting with these major issues, scientists and doctors pointed out the solutions for COVID and Related pandemics, in which the most populated solution, such as ultraviolet (UV)-based disinfection systems. This article is presenting a unique technology for the COVID-19 infected surfaces to either sides. The proposed research is the providing the solutions with the integration/merging of two different technologies in the portable form to provide a unique disinfection system to disinfect the infected/suspected surfaces by ‘Coronavirus disease’ from top and bottom side by exposing the specified samples like currencies/hand held devices/mobile phones/various types of cards, etc. According to the various literatures, ultraviolet-C light as well as 650 nm laser light has the power to destroy the COVID-19 and related viruses. The proposed system is developed to disinfect the above-mentioned items surfaces from COVID-19 like issues and has the ability to disinfect the items in few second (within 3–5 s). The proposed system has the capability to serve the nation at different level as it may be designed and developed in different sizes as per the application. This integrated technology can serve the society in most of the applications like, the major field for disinfection is food and agriculture sectors. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

18.
6th International Conference on System-Integrated Intelligence, SysInt 2022 ; 546 LNNS:116-125, 2023.
Article in English | Scopus | ID: covidwho-2048151

ABSTRACT

The global COVID-19 pandemic has stimulated the use of disinfection robots: in September 2021, following a European Commission’s action, 200 disinfection robots were delivered to European Hospitals. UV-C light is a common disinfection method, however, direct exposure to UV-C radiation is harmful and disinfection can be operated only in areas strictly forbidden to human personnel. We believe more advanced safety mechanisms are needed to increase the operational flexibility and safety level. We propose a safety mechanism based on vision and artificial intelligence, optimised for execution on mobile robot platforms. It analyses in real-time four video streaming and disables UV-C lamps when needed. Concerning other detection methods, it has a relatively wider and deeper range, and the capability to operate in a dynamic environment. We present the development of the method with a performance comparison of different implementation solutions, and an on-field evaluation through integration on a mobile disinfection robot. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

19.
Indoor Air ; 32(9): e13115, 2022 09.
Article in English | MEDLINE | ID: covidwho-2042837

ABSTRACT

Surface residing SARS-CoV-2 is efficiently inactivated by UV-C irradiation. This raises the question whether UV-C-based technologies are also suitable to decontaminate SARS-CoV-2- containing aerosols and which doses are needed to achieve inactivation. Here, we designed a test bench to generate aerosolized SARS-CoV-2 and exposed the aerosols to a defined UV-C dose. Our results demonstrate that the exposure of aerosolized SARS-CoV-2 with a low average dose in the order of 0.42-0.51 mJ/cm2 UV-C at 254 nm resulted in more than 99.9% reduction in viral titers. Altogether, UV-C-based decontamination of aerosols seems highly effective to achieve a significant reduction in SARS-CoV-2 infectivity.


Subject(s)
Air Pollution, Indoor , COVID-19 , Humans , Respiratory Aerosols and Droplets , SARS-CoV-2 , Ultraviolet Rays
20.
Frontiers of Environmental Science & Engineering ; 17(3), 2023.
Article in English | ProQuest Central | ID: covidwho-2027649

ABSTRACT

The COVID-19 pandemic remains ever prevalent and afflicting—partially because one of its transmission pathways is aerosol. With the widely used central air conditioning systems worldwide, indoor virus aerosols can rapidly migrate, thus resulting in rapid infection transmission. It is therefore important to install microbial aerosol treatment units in the air conditioning systems, and we herein investigated the possibility of combining such filtration with UV irradiation to address virus aerosols. Results showed that the removal efficiency of filtration towards f2 and MS2 phages depended on the type of commercial filter material and the filtration speed, with an optimal velocity of 5 cm/s for virus removal. Additionally, it was found that UV irradiation had a significant effect on inactivating viruses enriched on the surfaces of filter materials;MS2 phages had greater resistance to UV-C irradiation than f2 phages. The optimal inactivation time for UV-C irradiation was 30 min, with higher irradiation times presenting no substantial increase in inactivation rate. Moreover, excessive virus enrichment on the filters decreased the inactivation effect. Timely inactivation is therefore recommended. In general, the combined system involving filtration with UV-C irradiation demonstrated a significant removal effect on virus aerosols. Moreover, the system is simple and economical, making it convenient for widespread implementation in air-conditioning systems.

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