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1.
Rheum Dis Clin North Am ; 48(4): 827-843, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2132208

ABSTRACT

Systemic lupus erythematosus (SLE) is a complex, chronic autoimmune disease. The etiology of SLE is multifactorial and includes potential environmental triggers, which may occur sequentially (the "multi-hit" hypothesis). This review focuses on SLE risk potentially associated with environmental factors including infections, the microbiome, diet, respirable exposures (eg, crystalline silica, smoking, air pollution), organic pollutants, heavy metals, and ultraviolet radiation.


Subject(s)
Environmental Exposure , Lupus Erythematosus, Systemic , Humans , Environmental Exposure/adverse effects , Ultraviolet Rays/adverse effects , Lupus Erythematosus, Systemic/epidemiology , Lupus Erythematosus, Systemic/etiology , Smoking , Risk Factors
2.
PLoS One ; 17(11): e0268863, 2022.
Article in English | MEDLINE | ID: covidwho-2112689

ABSTRACT

BACKGROUND: The reprocessing of daily used medical devices is often inadequate, making them a potential source of infection. In addition, there are usually no consistent and technically standardized procedures available for this purpose. Hence, the aim of this study is to analyze the bacterial contamination and the effectiveness of Ultraviolet light-based (UV light-based) reprocessing of daily used medical devices. MATERIAL AND METHODS: Six different everyday medical devices (20 each; stethoscopes, tourniquets, bandage scissors, reflex hammers, tuning forks, and nystagmus glasses) were tested for bacterial contamination. All medical devices were then exposed to UV-C light for 25 seconds. Medical devices with a smooth surface were pre-cleaned with a water-based wipe. Contact samples were taken before and after reprocessing. RESULTS: Immediately after clinical use, 104 of 120 contact samples showed an average bacterial contamination of 44.8±64.3 colony forming units (CFU) (0-300 CFU), also including potentially pathogenic bacteria. Two further culture media were completely overgrown with potentially pathogenic bacteria. The stethoscopes were found to have the highest average contamination of 90±91.6 CFU. After reprocessing, 118 of 120 samples were sterile, resulting in an average residual contamination of 0.02±0.1 CFU in two samples, whereby only bacteria of the ordinary skin flora were found. CONCLUSION: The present study shows the potentially clinically relevant bacterial contamination of everyday used medical devices. The reprocessing method tested here using UV light appears to be a suitable method for disinfection, especially for objects that up to now have been difficult to disinfect or cannot be disinfected in a standardized manner.


Subject(s)
Equipment Contamination , Ultraviolet Rays , Equipment Contamination/prevention & control , Disinfection/methods , Bacteria , Drug Contamination
3.
Sci Rep ; 12(1): 18640, 2022 Nov 04.
Article in English | MEDLINE | ID: covidwho-2106472

ABSTRACT

Disinfection eliminates pathogenic microorganisms and ensures a biosafe environment for human beings. The rapid spread of COVID-19 is challenging traditional disinfection methods in terms of reducing harmful side effects and conducting faster processes. Spraying large-scale chemical disinfectants is harmful to individuals and the environment, while UV lamp and light-emitting diode (LED) disinfection still requires a long exposure time due to the low irradiance and highly divergent beam characteristics. Given that a laser maintains a high irradiance over a long distance, we studied the effectiveness of lasers as a new disinfection method, and the results show the capability for ultrafast inactivation of SARS-CoV-2 virus with a 266 nm laser. This work confirms UV lasers as a good candidate for disinfection.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Ultraviolet Rays , Disinfection/methods , Lasers , Virus Inactivation
4.
In Vivo ; 36(6): 2689-2699, 2022.
Article in English | MEDLINE | ID: covidwho-2100678

ABSTRACT

BACKGROUND/AIM: The rapid spread of COVID-19 resulted in the revision of the value of ultraviolet C (UVC) sterilization in working spaces. This study aimed at re-evaluating the anti-UVC activity of four groups of natural products against human melanoma COLO679 and human normal dermal fibroblast (HDFa) cells, based on chemotherapeutic index. MATERIALS AND METHODS: Various cell lines were exposed to UVC for 3 min in the presence of increasing concentrations of test compounds and viable cell numbers were determined with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The anti-UVC activity was quantified by the ratio of the 50% cytotoxic concentration (determined without irradiation) to the 50% effective concentration (which abolished by 50% the UVC-induced loss of viability). Apoptosis was quantified as the subG1 population proportion following cell-cycle analysis. RESULTS: Among four groups of major natural products, six phenylpropanoids showed the highest anti-UVC activity, followed by the lignified products and alkaline products that contain lignin and its degradation products. On the other hand, tannins and flavonoids showed lower activity due to their higher cytotoxicity. UVC-sensitive COLO679 cells lack dectin-1 protein expression. CONCLUSION: These data suggest the prominent anti-UVC activity of lignin degradation products, and the possible involvement of dectin-1 expression in UVC-sensitivity.


Subject(s)
Biological Products , COVID-19 , Melanoma , Humans , Lignin/pharmacology , Ultraviolet Rays , Biological Products/pharmacology
6.
Int J Environ Res Public Health ; 19(21)2022 Oct 23.
Article in English | MEDLINE | ID: covidwho-2081863

ABSTRACT

In the context of ongoing and future pandemics, non-pharmaceutical interventions are critical in reducing viral infections and the emergence of new antigenic variants while the population reaches immunity to limit viral transmission. This study provides information on efficient and fast methods of disinfecting surfaces contaminated with different human coronaviruses (CoVs) in healthcare settings. The ability to disinfect three different human coronaviruses (HCoV-229E, MERS-CoV, and SARS-CoV-2) on dried surfaces with light was determined for a fully characterized pulsed-xenon ultraviolet (PX-UV) source. Thereafter, the effectiveness of this treatment to inactivate SARS-CoV-2 was compared to that of conventional low-pressure mercury UVC lamps by using equivalent irradiances of UVC wavelengths. Under the experimental conditions of this research, PX-UV light completely inactivated the CoVs tested on solid surfaces since the infectivity of the three CoVs was reduced up to 4 orders of magnitude by PX-UV irradiation, with a cumulated dose of as much as 21.162 mJ/cm2 when considering all UV wavelengths (5.402 mJ/cm2 of just UVC light). Furthermore, continuous irradiation with UVC light was less efficient in inactivating SARS-CoV-2 than treatment with PX-UV light. Therefore, PX-UV light postulates as a promising decontamination measure to tackle the propagation of future outbreaks of CoVs.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Ultraviolet Rays , Xenon , Pandemics/prevention & control , Disinfection/methods
7.
Sci Rep ; 12(1): 16664, 2022 Oct 05.
Article in English | MEDLINE | ID: covidwho-2050544

ABSTRACT

The spread of SARS-CoV-2 infections and the severity of the coronavirus disease of 2019 (COVID-19) pandemic have resulted in the rapid development of medications, vaccines, and countermeasures to reduce viral transmission. Although new treatment strategies for preventing SARS-CoV-2 infection are available, viral mutations remain a serious threat to the healthcare community. Hence, medical devices equipped with virus-eradication features are needed to prevent viral transmission. UV-LEDs are gaining popularity in the medical field, utilizing the most germicidal UVC spectrum, which acts through photoproduct formation. Herein, we developed a portable and rechargeable medical device that can disinfect SARS-CoV-2 in less than 10 s by 99.9%, lasting 6 h. Using this device, we investigated the antiviral effect of UVC-LED (275 nm) against SARS-CoV-2 as a function of irradiation distance and exposure time. Irradiation distance of 10-20 cm, < 10 s exposure time, and UV doses of > 10 mJ/cm2 were determined optimal for SARS-CoV-2 elimination (≥ 99.99% viral reduction). The UVC-LED systems have advantages such as fast-stabilizing intensity and insensitivity to temperature, and may contribute to developing medical devices capable of containing SARS-CoV-2 infection. By demonstrating SARS-CoV-2 inactivation with very short-term UVC-LED irradiation, our study may suggest guidelines for securing a safer medical environment.


Subject(s)
COVID-19 , SARS-CoV-2 , Antiviral Agents , COVID-19/prevention & control , Disinfection/methods , Humans , Pandemics , Ultraviolet Rays , Virus Inactivation/radiation effects
8.
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
9.
Appl Environ Microbiol ; 88(19): e0122122, 2022 Oct 11.
Article in English | MEDLINE | ID: covidwho-2038232

ABSTRACT

The objective of this study was to evaluate the effectiveness of UV technology for virus disinfection to allow FFR reuse. UV is a proven decontamination tool for microbial pathogens, including the SARS-CoV-2 virus. Research findings suggest that the impacts of UV-C treatment on FFR material degradation should be confirmed using microbial surrogates in addition to the commonly performed abiotic particle testing. This study used the surrogates, E. coli and MS-2 bacteriophage, as they bracket the UV response of SARS-CoV-2. Lower log inactivation was observed on FFRs than predicted by aqueous-based UV dose-response data for MS-2 bacteriophage and E. coli. In addition, the dose-response curves did not follow the trends commonly observed with aqueous data for E. coli and MS-2. The dose-response curves for the respirators in this study had a semicircle shape, where the inactivation reached a peak and then decreased. This decrease in UV inactivation is thought to be due to the degradation of the fibers of the FFR and allows for more viral and bacterial cells to wash through the layers of the respirator. This degradation phenomenon was observed at UV doses at and above 2,000 mJ/cm2. Results have demonstrated that FFR materials yield various results in terms of effective disinfection in experiments conducted on KN95 and N95 face respirators. The highest inactivation for both surrogates was observed with the KN95 respirator made by Purism, yielding 3 and 2.75 log inactivation for E. coli and MS-2 at UV doses of 1,500 mJ/cm2. The KN95 made by Anboruo yielded the lowest inactivation for MS-2 at 0.75 log when exposed to 1,000 mJ/cm2. To further test the degradation theory, experiments used a collimated beam device to test the hypothesis further that degradation is occurring at and above UV doses of 1,500 mJ/cm2. The experiment aimed to determine the effect of "predosing" a respirator with UV before inoculating the respirator with MS-2. In this test, quantification of the penetrated irradiance value and the ability of each layer to retain MS-2 were quantified. The results of the experiments varied from the intact FFR degradation experiments but displayed some data to support the degradation theory. IMPORTANCE Research suggests degradation of FFR materials at high UV doses is important. There appears to be a peak inactivation dose at approximately 1,500 mJ/cm2. The subsequent dose increases appear to have the reverse effect on inactivation values; these trends have shown true with both the N95 and KN95-Purism respirators.


Subject(s)
COVID-19 , Disinfection , COVID-19/prevention & control , Decontamination/methods , Disinfection/methods , Escherichia coli , Humans , N95 Respirators , SARS-CoV-2 , Ultraviolet Rays , Ventilators, Mechanical
10.
Sci Total Environ ; 850: 157851, 2022 Dec 01.
Article in English | MEDLINE | ID: covidwho-2036502

ABSTRACT

The rapid spread of coronavirus disease 2019 has increased the consumption of some antiviral drugs, wherein these are discharged into wastewater, posing risks to the ecosystem and human health. Therefore, efforts are being made for the development of advanced oxidation processes (AOPs) to remediate water containing these pharmaceuticals. Here, the toxicity evolution of the antiviral drug ribavirin (RBV) was systematically investigated during its degradation via the UV/TiO2/H2O2 advanced oxidation process. Under optimal conditions, RBV was almost completely eliminated within 20 min, although the mineralization rate was inadequate. Zebrafish embryo testing revealed that the ecotoxicity of the treated RBV solutions increased at some stages and decreased as the reaction time increased, which may be attributed to the formation and decomposition of various transformation products (TPs). Liquid chromatography-mass spectrometry analysis along with density functional theory calculations helped identify possible toxicity increase-causing TPs, and quantitative structure activity relationship prediction revealed that most TPs exhibit higher toxicity than the parent compound. The findings of this study suggest that, in addition to the removal rate of organics, the potential ecotoxicity of treated effluents should also be considered when AOPs are applied in wastewater treatment.


Subject(s)
COVID-19 , Water Pollutants, Chemical , Water Purification , Animals , Antiviral Agents/analysis , Antiviral Agents/toxicity , Ecosystem , Humans , Hydrogen Peroxide/chemistry , Oxidation-Reduction , Pharmaceutical Preparations , Ribavirin/toxicity , Ultraviolet Rays , Waste Water/chemistry , Water/analysis , Water Pollutants, Chemical/analysis , Water Purification/methods , Zebrafish
11.
Viruses ; 14(9)2022 09 14.
Article in English | MEDLINE | ID: covidwho-2033148

ABSTRACT

The current pandemic caused by severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) has encouraged the evaluation of novel instruments for disinfection and lowering infectious pressure. Ultraviolet subtype C (UVC) excimer lamps with 222 nm wavelength have been tested on airborne pathogens on surfaces and the exposure to this wavelength has been considered safer than conventional UVC. To test the efficacy of UVC excimer lamps on coronaviruses, an animal model mimicking the infection dynamics was implemented. An attenuated vaccine based on infectious bronchitis virus (IBV) was nebulized and irradiated by 222 nm UVC rays before the exposure of a group of day-old chicks to evaluate the virus inactivation. A control group of chicks was exposed to the nebulized vaccine produced in the same conditions but not irradiated by the lamps. The animals of both groups were sampled daily and individually by choanal cleft swabs and tested usign a strain specific real time RT-PCR to evaluate the vaccine replication. Only the birds in the control group were positive, showing an active replication of the vaccine, revealing the efficacy of the lamps in inactivating the vaccine below the infectious dose in the other group.


Subject(s)
COVID-19 , Ultraviolet Rays , Animals , Chickens , Disease Models, Animal , Disinfection , SARS-CoV-2 , Vaccines, Attenuated
12.
In Vivo ; 36(5): 2116-2125, 2022.
Article in English | MEDLINE | ID: covidwho-2030531

ABSTRACT

BACKGROUND/AIM: Rapid spread of COVID-19 resulted in the revision of the value of ultraviolet C (UVC) sterilization in working spaces. This study aimed at investigating the UVC sensitivity of eighteen malignant and nonmalignant cell lines, the protective activity of sodium ascorbate against UVC, and whether Dectin-2 is involved in UVC sensitivity. MATERIALS AND METHODS: Various cell lines were exposed to UVC for 3 min, and cell viability was determined using the MTT assay. Anti-UV activity was determined as the ratio of 50% cytotoxic concentration (determined with unirradiated cells) to 50% effective concentration (that restored half of the UV-induced loss of viability). Dectin-2 expression was quantified using flow cytometry. RESULTS: The use of culture medium rather than phosphate-buffered saline is recommended as irradiation solution, since several cells are easily detached during irradiation in phosphate-buffered saline. Oral squamous cell carcinoma cell lines showed the highest UV sensitivity, followed by neuroblastoma, glioblastoma, leukemia, melanoma, lung carcinoma cells, and normal oral and dermal fibroblasts. Human dermal fibroblasts were more resistant than melanoma cell lines; however, both expressed Dectin-2. Sodium ascorbate at micromolar concentrations eliminated the cytotoxicity of UVC in these cell lines. CONCLUSION: Normal cells are generally UVC-resistant compared to corresponding malignant cells, which have higher growth potential. Dectin-2 protein expression itself may not be determinant of UVC sensitivity.


Subject(s)
COVID-19 , Carcinoma, Squamous Cell , Melanoma , Mouth Neoplasms , Ascorbic Acid/pharmacology , Humans , Lectins, C-Type , Phosphates , Ultraviolet Rays
13.
Sci Rep ; 12(1): 14545, 2022 08 25.
Article in English | MEDLINE | ID: covidwho-2016826

ABSTRACT

There is an urgent need for evidence-based engineering controls to reduce transmission of SARS-CoV-2, which causes COVID-19. Although ultraviolet (UV) light is known to inactivate coronaviruses, conventional UV lamps contain toxic mercury and emit wavelengths (254 nm) that are more hazardous to humans than krypton chlorine excimer lamps emitting 222 nm (UV222). Here we used culture and molecular assays to provide the first dose response for SARS-CoV-2 solution exposed to UV222. Culture assays (plaque infectivity to Vero host) demonstrated more than 99.99% disinfection of SARS-CoV-2 after a UV222 dose of 8 mJ/cm2 (pseudo-first order rate constant = 0.64 cm2/mJ). Immediately after UV222 treatment, RT-qPCR assays targeting the nucleocapsid (N) gene demonstrated ~ 10% contribution of N gene damage to disinfection kinetics, and an ELISA assay targeting the N protein demonstrated no contribution of N protein damage to disinfection kinetics. Molecular results suggest other gene and protein damage contributed more to disinfection. After 3 days incubation with host cells, RT-qPCR and ELISA kinetics of UV222 treated SARS-CoV-2 were similar to culture kinetics, suggesting validity of using molecular assays to measure UV disinfection without culture. These data provide quantitative disinfection kinetics which can inform implementation of UV222 for preventing transmission of COVID-19.


Subject(s)
COVID-19 , Disinfection , COVID-19/prevention & control , Chlorine , Disinfection/methods , Humans , SARS-CoV-2 , Ultraviolet Rays
14.
PLoS One ; 17(9): e0273078, 2022.
Article in English | MEDLINE | ID: covidwho-2009692

ABSTRACT

A growing number of studies suggest that climate may impact the spread of COVID-19. This hypothesis is supported by data from similar viral contagions, such as SARS and the 1918 Flu Pandemic, and corroborated by US influenza data. However, the extent to which climate may affect COVID-19 transmission rates and help modeling COVID-19 risk is still not well understood. This study demonstrates that such an understanding is attainable through the development of regression models that verify how climate contributes to modeling COVID-19 transmission, and the use of feature importance techniques that assess the relative weight of meteorological variables compared to epidemiological, socioeconomic, environmental, and global health factors. The ensuing results show that meteorological factors play a key role in regression models of COVID-19 risk, with ultraviolet radiation (UV) as the main driver. These results are corroborated by statistical correlation analyses and a panel data fixed-effect model confirming that UV radiation coefficients are significantly negatively correlated with COVID-19 transmission rates.


Subject(s)
COVID-19 , Influenza, Human , COVID-19/epidemiology , Climate , Climate Change , Humans , Ultraviolet Rays/adverse effects
15.
J Virol Methods ; 309: 114610, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2007918

ABSTRACT

Inactivation of human respiratory viruses in air and on surfaces is important to control their spread. Exposure to germicidal ultraviolet (UV-C) light damages viral nucleic acid rendering them non-infectious. Most of the recent viral inactivation studies have not considered potential artifacts caused by interactions between UV-C light and culture media used to suspend and deposit virus on surfaces. We show that the reactive oxygen and nitrogen species (ROS and RNS) form when commonly used virus culture media is exposed to 265 nm irradiation from light emitting diodes (LEDs) at UV-C doses (4 or 40 mJ/cm2) commonly considered to achieve multiple log-inactivation of virus. Surface viral inactivation values were enhanced from 0.49 to 2.92 log10 of viruses in DMEM, EMEM or EMEM-F as compared to absence of culture media (only suspended in Tris-buffer). The mechanisms responsible for the enhanced surface inactivate is hypothesized to involve photo-activation of vitamins and dyes present in the culture media, deposited with the virus on surfaces to be disinfected, which produce ROS and RNS. Given the rapidly growing research and commercial markets for UV-C disinfecting devices, there is a need to establish surface disinfecting protocols that avoid viral inactivation enhancement artifacts associated with selection and use of common cell culture media in the presence of UV-C light. This study addresses this weak link in the literature and highlights that inadequate selection of virus suspension media may cause a bias (i.e., over-estimation) for the UV-C dosages required for virus inactivation on surfaces.


Subject(s)
Nucleic Acids , Viruses , Bias , Cell Culture Techniques , Coloring Agents , Culture Media , Disinfection/methods , Humans , Nitrogen , Oxygen , Reactive Oxygen Species , Ultraviolet Rays , Virus Inactivation/radiation effects , Vitamins
16.
Int J Biol Macromol ; 221: 71-82, 2022 Nov 30.
Article in English | MEDLINE | ID: covidwho-2007741

ABSTRACT

The spreading of coronavirus from contacting surfaces and aerosols created a pandemic around the world. To prevent the transmission of SARS-CoV-2 virus and other contagious microbes, disinfection of contacting surfaces is necessary. In this study, a disinfection box equipped with infrared (IR) radiation heating and ultraviolet-C (UV-C) radiation is designed and tested for its disinfection ability against pathogenic bacteria and SARS-CoV-2 spike protein. The killing of a Gram-positive, namely, S. aureus and a Gram-negative namely, S. typhi bacteria was studied followed by the inactivation of the spike protein. The experimental parameters were optimized using a statistical tool. For the broad-spectrum antibacterial activity, the optimum condition was holding at 65.61 °C for 13.54 min. The killing of the bacterial pathogen occurred via rupturing the cell walls as depicted by electron microscopy. Further, the unfolding of SARS-CoV-2 spike protein and RNase A was studied under IR and UV-C irradiations at the aforesaid optimized condition. The unfolding of both the proteins was confirmed by changes in the secondary structure, particularly an increase in ß-sheets and a decrease in α-helixes. Remarkably, the higher penetration depth of IR waves up to subcutaneous tissue resulted in lower optimum disinfection temperature, <70 °C in vogue. Thus, the combined UV-C and IR radiation is effective in killing the pathogenic bacteria and denaturing the glycoproteins.


Subject(s)
COVID-19 , Spike Glycoprotein, Coronavirus , Humans , Disinfection/methods , SARS-CoV-2 , Staphylococcus aureus , Respiratory Aerosols and Droplets , Ultraviolet Rays
17.
Int J Pharm Compd ; 26(5): 432-435, 2022.
Article in English | MEDLINE | ID: covidwho-2006864

ABSTRACT

Airborne infectious diseases have been a major worldwide concern for many years. The sudden and fast spread of the severe acute respiratory syndrome 2, causing the coronavirus disease 2019 in a pandemic form, has intensified the necessity of constant environmental disinfection. Among the possible technologies that can be used for air disinfection is the ultraviolet germicidal irradiation through the use of ultraviolet C light. The main mechanism involved in ultraviolet C light inactivation of microorganisms such as viruses, bacteria, protozoa, fungi, yeasts, and others is mainly due to its capacity to promote dimerization of pyrimidine, disturbing the microorganism's DNA (and RNA) replication and transcription, therefore leading to cell death. The aim of this study was to validate the efficacy of a new ultraviolet C light disinfection system to deactivate viruses such as coronavirus in different environmental conditions. The device was effective in the neutralization of airborne particles containing coronavirus genus samples, presenting >99.99% of inactivation rate in an aerosolization test, simulating the real conditions in which this virus is most transmitted in different environments.


Subject(s)
COVID-19 , Disinfection , Bacteria , COVID-19/prevention & control , Fungi , Humans , Ultraviolet Rays
18.
J Photochem Photobiol B ; 235: 112551, 2022 Oct.
Article in English | MEDLINE | ID: covidwho-2004277

ABSTRACT

A thin, 30 µm, flexible, robust low-density polyethylene, LDPE, film, loaded with 30 wt% P25 TiO2, is extruded and subsequently rendered highly active photocatalytically by exposing it to UVA (352 nm, 1.5 mW cm-2) for 144 h. The film was tested for anti-viral activity using four different viruses, namely, two strains of Influenza A Virus (IAV), WSN, and a recombinant PR8, encephalomyocarditis virus (EMCV), and SARS-CoV-2 (SARS2). The film was irradiated with either UVA radiation (352 nm, 1.5 mW cm-2; although only 0.25 mW cm-2 for SARS2) or with light from a cool white fluorescent lamp (UVA irradiance: 365 nm, 0.047 mW cm-2). In all cases the films exhibited an average virus inactivation rate of >1.5log/h. In the case of SARS2, the rates were > 2log/h, with the rate determined using a dedicated, low intensity UVA source (0.25 mW cm-2) only 1.3 x's faster than that for a cool white lamp (UVA irradiance = 0.047 mW cm-2), which suggests that SARS2 is particularly prone to photocatalytic inactivation even under low UV irradiation conditions, such as found in a room lit with just white fluorescent tubes. This is the first example of a flexible, very thin, photocatalytic plastic film, produced by a scalable process (extrusion), for virus inactivation. The potential of such a film for use as a disposable, self-sterilising thin plastic material alternative to the common, non-photocatalytic, inert equivalent used currently for curtains, aprons and table coverings in healthcare is discussed briefly.


Subject(s)
COVID-19 , Titanium , Catalysis , Humans , Plastics , Polyethylene , SARS-CoV-2 , Ultraviolet Rays
19.
Environ Sci Technol ; 56(17): 12424-12430, 2022 09 06.
Article in English | MEDLINE | ID: covidwho-2000844

ABSTRACT

Behavioral and medical control measures have not been effective in containing the spread of SARS-CoV-2 in large part due to the unwillingness of populations to adhere to "best practices". Ultraviolet light with wavelengths of between 200 and 280 nm (UV-C) and, in particular, germicidal ultraviolet light, which refers to wavelengths around 254 nm, have the potential to unobtrusively reduce the risk of SARS-CoV-2 transmission in enclosed spaces. We investigated the effectiveness of a strategy using UV-C light to prevent airborne transmission of the virus in a hamster model. Treatment of environmental air with 254 nm UV-C light prevented transmission of SARS-CoV-2 between individuals in a model using highly susceptible Syrian golden hamsters. The prevention of transmission of SARS-CoV-2 in a natural system by treating elements of the surrounding environment is one more weapon in the arsenal to combat COVID. The results presented indicate that coupling mitigation strategies utilizing UV-C light, along with current methods to reduce transmission risk, have the potential to allow a return to normal indoor activities.


Subject(s)
COVID-19 , SARS-CoV-2 , Animals , Cricetinae , Humans , Respiratory Aerosols and Droplets , Ultraviolet Rays
20.
Am J Infect Control ; 50(8): 947-953, 2022 08.
Article in English | MEDLINE | ID: covidwho-2000206

ABSTRACT

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.


Subject(s)
Radiology , Robotics , Disinfection/methods , Hospitals , Humans , Ultraviolet Rays
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