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1.
Environmental Science and Technology Letters ; 2022.
Article in English | Scopus | ID: covidwho-2211876

ABSTRACT

Ultraviolet germicidal irradiation (UVGI) is known to inactivate various viruses and bacteria, including SARS-CoV-2, and is widely applied especially in medical facilities. This inactivation results from the high photon energies causing molecular bonds to break, but when nonpathogen molecules are affected, unwanted effects may occur. Here, we explored the effect of a commercial high-intensity (∼2 kW) UVC disinfection device on the composition and concentration of gases and particles in indoor air. We find that the UVC (254 nm) caused dramatic increases in particle number concentrations, and nearly all (∼1000) monitored gas phase species also increased. These responses were unsurprising when considering the typical impacts of UVC on atmospheric chemistry. High particle concentrations are associated with adverse health effects, suggesting that the impact of UVGI devices on indoor air quality (IAQ) should be studied in much more detail. The high-intensity device in this study was intended for short durations in unoccupied rooms, but lower-intensity devices for continuous use in occupied rooms are also widely applied. This makes further studies even more urgent, as the potential IAQ effects of these approaches remain largely unexplored. © 2023 The Authors. Published by American Chemical Society.

2.
Int J Environ Sci Technol (Tehran) ; : 1-10, 2022 Oct 25.
Article in English | MEDLINE | ID: covidwho-2094821

ABSTRACT

Indoor environments such as healthcare centers are known as one of the key centers in the outbreak of viral infectious diseases. In the present study, the pathogenic agents' treatment system (PATS) was designed by the combination of non-thermal plasma (NTP) with the ultraviolet germicidal irradiation (UVGI) processes. Then, the treatment efficiency of PATS was measured for the "SARS-Co-V2." The exhaled air of the confirmed case of "COVID-19" was considered as the viral source of "SARS-Co-V2" and directed to the upstream of PATS. The treatment process was done by passing directed air through two steps of treatment (NTP and UVGI). The treatment efficiency of PATS was measured by sampling at the sampling points (before and after the treatment process). According to the energy emission pattern (corona discharge, UV rays) in the designed system, during two steps, the high efficiency of treatment for the collected pathogens was achieved. Based on the real-time polymerase chain reaction (RT-PCR) results, the CT value was lower than 29 (CTs < 29), and after the treatment using PATS was upper than 40 (CTs > 40) confirming the highest removal efficiency of "SARS-Co-V2." Also, the treatment efficiency of each reactor in individual operation was at the optimum level. The findings suggested, the present PATS may eliminate the viral pathogens with hospital sources and also, be applicable in the other intensive care unit (ICU) wards with the same risk thus, significantly reducing the possible exposure risk of healthcare and sick companions, and preventing the outbreak of infectious diseases.

3.
J Occup Environ Hyg ; : 1-20, 2022 Oct 18.
Article in English | MEDLINE | ID: covidwho-2077491

ABSTRACT

In emergencies like the COVID-19 pandemic, reuse or reprocessing of filtering facepiece respirators (FFRs) may be required to mitigate exposure risk. Research gap: Only a few studies evaluated decontamination effectiveness against SARS-CoV-2 that are practical for low-resource settings. This study aimed to determine the effectiveness of a relatively inexpensive ultraviolet germicidal irradiation chamber to decontaminate FFRs contaminated with SARS-CoV-2. A custom design UVGI chamber was constructed to determine the ability to decontaminate seven FFR models including N95s, KN95 and FFP2s inoculated with SARS-CoV-2. Vflex was excluded due to design folds/pleats and UVGI shadowing inside the chamber. Structural and functional integrity tolerated by each FFR model on repeated decontamination cycles was assessed. Twenty-seven participants were fit tested over 30 cycles for each model and passed if the fit factor was ≥100. Of the FFR models included for testing, only the KN95 model failed filtration. The 3M™ 3M 1860 and Halyard™ duckbill 46727 (formerly Kimberly Clark) models performed better on fit testing than other models for both pre-and-post decontaminations. Fewer participants (0.3 and 0.7%, respectively) passed fit testing for Makrite 9500 N95 and Greenline 5200 FFP2 and only two for the KN95 model post decontamination. Fit testing appeared to be more affected by donning & doffing, as some passed with adjustment and repeat fit testing. A ≥ 3 log reduction of SARS-CoV-2 was achieved for worn-in FFRs namely Greenline 5200 FFP2. Conclusion: The study showed that not all FFRs tested could withstand 30 cycles of UVGI decontamination without diminishing filtration efficiency or facial fit. In addition, SARS-CoV-2 log reduction varied across the FFRs, implying that the decontamination efficacy largely depends on the decontamination protocol and selection of FFRs. We demonstrated the effectiveness of a low-cost and scalable decontamination method for SARS-CoV-2 and the effect on fit testing using people instead of manikins. It is recognised that extensive experimental evidence for the reuse of decontaminated FFRs is lacking, and thus this study would be relevant and of interest in crisis-capacity settings, particularly in low-resource facilities.

4.
Building and Environment ; : 109699, 2022.
Article in English | ScienceDirect | ID: covidwho-2068748

ABSTRACT

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

5.
20th International Conference on Ship and Maritime Research, NAV 2022 ; 6:610-621, 2022.
Article in English | Scopus | ID: covidwho-2054924

ABSTRACT

The actual, global pandemic situation has dramatically involved every aspect of our lives. This also greatly affected the cruise ship industry. At first, cruise companies tried to face the problem by adapting existing ships at the situation, with no time to rethink completely their project. The opinion of scientists, architects and field experts highlighted the need to devise a new way to design cruise ships, considering passenger management, marketing and medical aspects. Particular attention must be paid to public areas, where individuals would be most vulnerable to airborne transmission. The sanitizing operations have now to follow even stricter operational protocols than in the past. A constant update monitoring of the passenger flows through the so-called smart technologies would allow, when dealing with a suspected case, to trace a timeline of its activities on board and, therefore, to avoid the rise of an outbreak. An implementation of the overall efficiency of vertical connections (which helps the management of potentially contaminated waste) and on-board medical spaces such as the hospital and the pharmacy shall be advised. From an anthropological point of view, it is essential to consider in more depth issues such as social distancing and the possibility of permanently decreasing the number of passengers, in favour of safety and on-board liveability. In the post COVID-19 era, the cruise ship can become a 'health bubble', a microcosm where people can enjoy an even more rewarding and safe experience. © 2022 The authors and IOS Press. All rights reserved.

6.
2022 ASABE Annual International Meeting ; 2022.
Article in English | Scopus | ID: covidwho-2040428

ABSTRACT

Since COVID-19 became a global pandemic, improving air quality has been increasingly important to mitigate the transmission of pathogenic aerosols. Air filters such as MERV filters have been widely used in heating, ventilation, and air conditioning (HVAC) systems to clean inlet air. In recent years, ultraviolet (UV) light has been used for decontamination and disinfection in various applications, including indoor air cleaning, e.g., upper-room ultraviolet germicidal irradiation (UVGI). There are a variety of air purification devices available in the market, with some incorporating UV technology. However, many of them are not formally tested and certified for their effectiveness in mitigating airborne pathogens and particulate matter. The research's objectives are to (1) evaluate, design, and upgrade an existing air filtration device (~2,200 CFM) with the addition of UV-C lamps;(2) test the effectiveness of the upgraded device in mitigating airborne pathogens (bacteria) and particulate matter (PM) in real scenario (poultry farm). The testing results of air quality are expressed in particular matter (PM) levels and colony-forming units (CFUs). The preliminary data showed that both MERV-8 & MERV 13 and UV-C lamps can inactivate up to 100% of airborne bacteria, and the device can remove over 95% of total PM after treatment in a ~150-layer room. © 2022 ASABE. All Rights Reserved.

7.
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
8.
Int J Environ Res Public Health ; 19(16)2022 08 11.
Article in English | MEDLINE | ID: covidwho-1987754

ABSTRACT

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


Subject(s)
Air Pollution, Indoor , COVID-19 , Cough , Humans , Hydrodynamics , Pandemics
9.
Light-Emitting Devices, Materials, and Applications XXVI 2022 ; 12022, 2022.
Article in English | Scopus | ID: covidwho-1891705

ABSTRACT

Ultraviolet Germicidal Irradiation (UVGI) is a proven method of disinfection for both bacterial and viral pathogens. Since the acceleration of the COVID-19 pandemic caused by SARS-CoV-2, the industry has witnessed significant technological innovation and an influx of UV-C LEDs, devices, and disinfectant enclosures. To ensure germicidal efficacy, UV-C LEDs and associated devices need accurate characterization of their optical power and irradiance. When UV-C sources are installed in enclosures and rooms, additional challenges arise that need to be evaluated to ensure germicidal efficacy is maintained. These challenges include 1) under- and over-dosing due to non-uniformity of UV-C dosage, 2) poorly understood room/chamber dynamics and reflectance, 3) shadowing, and 4) sensor, material, and source degradation. Here, we introduce a new detector portfolio that is calibrated at critical UV-C wavelengths, such as 265 nm, and enables real time UV-C Irradiance measurements at near-field and far-field. Temporal monitoring of irradiance allows for real time dosage calculation. Seasoned optical components ensure accurate detector performance and enable source output degradation monitoring. An adaptable API, network capability, and a dashboard facilitate simultaneous monitoring of multiple detectors and easy integration with existing installation infrastructure. With a proprietary cosine diffuser, these detectors include an exceptional f2 directional response making them ideal for deployment in rooms, enclosures, and HVAC systems. © COPYRIGHT SPIE. Downloading of the is permitted for personal use only.

10.
MAPAN |Journal of Metrology Society of India ; 37(2):237-249, 2022.
Article in English | ProQuest Central | ID: covidwho-1889067

ABSTRACT

Ultraviolet-C (UVC) radiation-based sanitization has globally gained enormous importance in the current COVID-19 (caused by SARS-COV-2 virus) pandemic situation. The effectiveness of radiation sanitization is quantified in terms of ‘radiation dose’, which in turn is derived from a radiometric parameter ‘irradiance’, measured using UVC radiometer. Metrological traceability of irradiance/dose measurement is essentially required for achieving requisite accuracy of measurements, and hence germicidal efficacy. In the present article, the derivation of traceability for irradiance measurement using UVC radiometer is demonstrated. The critical conditions to be considered while using detector/radiometer for measuring UVC irradiance/dose in practical conditions are elaborated, avoiding which, significant errors in the UVC irradiance/dose may arise, and hence, may compromise the performance of the Ultraviolet Germicidal Irradiation (UVGI) devices.

11.
Materials Today Sustainability ; : 100161, 2022.
Article in English | ScienceDirect | ID: covidwho-1867617

ABSTRACT

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

12.
Science & Technology for the Built Environment ; : 1-21, 2022.
Article in English | Academic Search Complete | ID: covidwho-1860770

ABSTRACT

The article describes a model for calculating the killing ratio of different pathogens with an in-duct ultraviolet (UV) device. The model is based on the radiosity method adapted for the UV radiation range and can be used for analysing any lamp distribution. The paper provides the necessary view factors and the influence of environmental variables (temperature, humidity and air velocity) in the analysis.The model has been validated using the results of four commercial equipment certificates issued by the US Environmental Protection Agency (EPA). The model results show a high precision on the test results, with a maximum deviation of 9%. In all cases, the model results are lower than that of the test, which allows being on the side of safety in the design.The model has been programmed in software used by Steril-Air for designing its equipment. Finally, an example of calculating the SARS-CoV-2 killing ratio with a 4x2 lamps arrangement is shown. [ FROM AUTHOR] Copyright of Science & Technology for the Built Environment is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

13.
J. Res. Natl. Inst. Stand. Technol. ; 126:29, 2022.
Article in English | Web of Science | ID: covidwho-1791942

ABSTRACT

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

14.
Heliyon ; 8(3): e09001, 2022 Mar.
Article in English | MEDLINE | ID: covidwho-1701202

ABSTRACT

The globally occurring recurrent waves of the COVID-19 pandemic, primarily caused by the transmission of aerosolized droplets from an infected person to a healthy person in the indoor environment, has led to the urgency of designing new modes of indoor ventilation. To prevent cross-contaminations due to airborne viruses, bacteria, and other pollutants in indoor environments, heating ventilation and air-conditioning (HVAC) systems need to be redesigned with anti-pandemic components. The three vital anti-pandemic components for the post-COVID-19 HVAC systems, as identified by the authors, are: a biological contaminant inactivation unit, a volatile organic compound decomposition unit, and an advanced air filtration unit. The purpose of the current article is to provide an overview of the latest research outcomes toward designing these anti-pandemic components and pointing out the future promises and challenges. In addition, the role of personalized ventilation in minimizing the risk of indoor cross-contamination by employing various air terminal devices is discussed. The authors believe that this article will encourage HVAC designers to develop effective anti-pandemic components to minimize the indoor airborne transmission.

15.
Energy (Oxf) ; 244: 122709, 2022 Apr 01.
Article in English | MEDLINE | ID: covidwho-1520890

ABSTRACT

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

16.
J Occup Environ Hyg ; 19(1): 67-77, 2022 Jan.
Article in English | MEDLINE | ID: covidwho-1467257

ABSTRACT

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 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.


Subject(s)
Air Pollution, Indoor , COVID-19 , Air Microbiology , Disinfection , Humans , SARS-CoV-2 , Ultraviolet Rays
17.
Int J Environ Res Public Health ; 18(19)2021 09 27.
Article in English | MEDLINE | ID: covidwho-1463639

ABSTRACT

This study aimed to detect airborne Mycobacterium tuberculosis (MTB) at nine public health facilities in three provinces of South Africa and determine possible risk factors that may contribute to airborne transmission. Personal samples (n = 264) and stationary samples (n = 327) were collected from perceived high-risk areas in district, primary health clinics (PHCs) and TB facilities. Quantitative real-time (RT) polymerase chain reaction (PCR) was used for TB analysis. Walkabout observations and work practices through the infection prevention and control (IPC) questionnaire were documented. Statistical analysis was carried out using Stata version 15.2 software. Airborne MTB was detected in 2.2% of samples (13/572), and 97.8% were negative. District hospitals and Western Cape province had the most TB-positive samples and identified risk areas included medical wards, casualty, and TB wards. MTB-positive samples were not detected in PHCs and during the summer season. All facilities reported training healthcare workers (HCWs) on TB IPC. The risk factors for airborne MTB included province, type of facility, area or section, season, lack of UVGI, and ineffective ventilation. Environmental monitoring, PCR, IPC questionnaire, and walkabout observations can estimate the risk of TB transmission in various settings. These findings can be used to inform management and staff to improve the TB IPC programmes.


Subject(s)
Mycobacterium tuberculosis , Occupational Exposure , Tuberculosis , Delivery of Health Care , Health Personnel , Humans , Infection Control , Mycobacterium tuberculosis/genetics , Occupational Exposure/analysis , South Africa/epidemiology , Tuberculosis/epidemiology
18.
J Photochem Photobiol ; 8: 100072, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1446893

ABSTRACT

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.

19.
J Photochem Photobiol ; 8: 100068, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1415593

ABSTRACT

A significant amount of epidemiological evidence has underlined that human-to-human transmission due to close contacts is considered the main pathway of transmission, however since the SARS-CoV-2 can also survive in aerosols, water, and surfaces, the development and implementation of effective decontamination strategies are urgently required. In this regard, ultraviolet germicidal irradiation (UVGI) using ultraviolet C (UVC) has been proposed to disinfect different environments and surfaces contaminated by SARS-CoV-2. Herein, we performed a systematic scoping review strictly focused on peer-reviewed studies published in English that reported experimental results of UVC-based technologies against the SARS-CoV-2 virus. Studies were retrieved from PubMed and the Web of Science database. After our criterious screening, we identified 13 eligible articles that used UVC-based systems to inactivate SARS-CoV-2. We noticed the use of different UVC wavelengths, technologies, and light doses. The initial viral titer was also heterogeneous among studies. Most studies reported virus inactivation in well plates, even though virus persistence on N95 respirators and different surfaces were also evaluated. SARS-CoV-2 inactivation reached from 90% to 100% depending on experimental conditions. We concluded that there is sufficient evidence to support the use of UVC-based technologies against SARS-CoV-2. However, appropriate implementation is required to guarantee the efficacy and safety of UVC strategies to control the COVID-19 pandemic.

20.
Build Environ ; 197: 107852, 2021 Jun 15.
Article in English | MEDLINE | ID: covidwho-1163455

ABSTRACT

The rapid increase in global cases of COVID-19 illness and death requires the implementation of appropriate and efficient engineering controls to improve indoor air quality. This paper focuses on the use of the ultraviolet germicidal irradiation (UVGI) air purification technology in HVAC ducts, which is particularly applicable to buildings where fully shutting down air recirculation is not feasible. Given the poor understanding of the in-duct UVGI system regarding its working mechanisms, designs, and applications, this review has the following key research objectives:•Identifying the critical parameters for designing a UVGI system, including the characterization of lamp output, behavior of the target microbial UV dose-response, and evaluation of the inactivation performance and energy consumption.•Elucidating the effects of environmental factors (air velocity, air temperature, and humidity) on the UVGI system design parameters and optimization of the in-duct UVGI design.•Summarizing existing UVGI system designs in the literature and illustrating their germicidal and energy performance in light of COVID-19 mitigation.

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