Germicidal Lamp Research Articles

Wireless, Accumulation Mode Dosimeters for Monitoring Pulsed and Non-Pulsed Germicidal Lamps

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

A Simple, Readily Accessible, and Effective Apparatus for the ­Photoisomerization of cis-Cyclooctenes to trans-Cyclooctenes

AbstractA simple, cost effective, and readily accessible apparatus for the photoisomerization of cis-cyclooctenes to trans-cyclooctenes is described. Utilizing only FEP tubing, aluminum vent pipe, a household germicidal lamp, and a flash chromatography system, trans-cyclooctenes can be prepared in good yield.

Output Reduction over Time of Germicidal UV-C Lamps Used for Treating Agricultural Crops

ABSTRACT It is important in understanding the potential benefits of ultraviolet (UV-C) field applications for control of powdery mildew to know how long the lamps will last before replacement. We conducted a laboratory evaluation of a sample of low-pressure discharge germicidal UV-C lamps that have been used in field trials to control strawberry powdery mildew. None of the lamps tested failed to start after more than a year of operation. The degradation of UV-C output followed trends similar to those described by the manufacturer. Based on these measurement data and on the long history of this lamp technology, we predict that these lamps can continue to perform in the field after the manufacturer’s rated life of approximately 10,000 hours of continuous operation, by reducing the speed of application to deliver the prescribed UV-C dose. With protective sleeves, these low pressure discharge UV-C lamps can be expected to last for many years of service.

Low-Cost Germicidal UV LED as Candidate Light Source for Portable and Field Spectrometer

Ultraviolet Light Emitting Diode (UV LED) is becoming popular, especially during the Covid-19 pandemic. UV LED has a specific wavelength with relatively narrow bandwidth, especially the one that has a shorter wavelength. On the other hand, UV LED has advantages in its low power consumption, compact size, and longer lifetime. This work shows that a wider bandwidth can be elicited by combining multiple UV LED sources. We have measured several low-cost UV LED, which is used as a germicidal lamp using a portable spectrometer that can detect a wavelength from 200 nm to 850 nm. The combined UV LED spectrum light ranges from 254 nm UVC to 400 nm UVA. The light spectrum produced by the LED shows a form of the Gaussian distribution model. Some LEDs have a peak wavelength at UVC around 270nm, and LEDs have a peak wavelength around 400nm at UVA. We can conclude that the low-cost UV LED can be used as a light source for portable or field spectrometers for specific wavelength.

Response of Escherichia coli minimal ter operon to UVC and auto-aggregation: pilot study.

AimThe study of minimal ter operon as a determinant of tellurium resistance (TeR) is important for the purpose of confirming the relationship of these genes to the pathogenicity of microorganisms. The ter operon is widespread among bacterial species and pathogens, implicated also in phage inhibition, oxidative stress and colicin resistance. So far, there is no experimental evidence for the role of the Escherichia coli (E. coli) minimal ter operon in ultraviolet C (UVC) resistance, biofilm formation and auto-aggregation. To identify connection with UVC resistance of the minimal ter operon, matched pairs of Ter-positive and -negative E. coli cells were stressed and differences in survival and whole genome sequence analysis were performed. This study was aimed also to identify differences in phenotype of cells induced by environmental stress.MethodsIn the current study, a minimal ter operon(terBCDEΔF) originating from the uropathogenic strain E. coli KL53 was used. Clonogenic assay was the method of choice to determine cell reproductive death after treatment with UVC irradiation at certain time intervals. Bacterial suspensions were irradiated with 254 nm UVC-light (germicidal lamp in biological safety cabinet) in vitro. UVC irradiance output was 2.5 mW/cm2 (calculated at the UVC device aperture) and plate-lamp distance of 60 cm. DNA damage analysis was performed using shotgun sequencing on Illumina MiSeq platform. Biofilm formation was measured by a crystal violet retention assay. Auto-aggregation assay was performed according to the Ghane, Babaeekhou & Ketabi (2020).ResultsA large fraction of Ter-positive E. coli cells survived treatment with 120-s UVC light (300 mJ/cm2) compared to matched Ter-negative cells; ∼5-fold higher resistance of Ter-positive cells to UVC dose (p = 0.0007). Moreover, UVC surviving Ter-positive cells showed smaller mutation rate as Ter-negative cells. The study demonstrated that a 1200-s exposure to UVC (3,000 mJ/cm2) was sufficient for 100% inhibition of growth for all the Ter-positive and -negative E. coli cells. The Ter-positive strain exhibited of 26% higher auto-aggregation activities and was able to inhibit biofilm formation over than Ter- negative strain (**** P < 0.0001).ConclusionOur study shows that Ter-positive cells display lower sensitivity to UVC radiation, corresponding to a presence in minimal ter operon. In addition, our study suggests that also auto-aggregation ability is related to minimal ter operon. The role of the minimal ter operon (terBCDEΔF) in resistance behavior of E. coli under environmental stress is evident.

Neutralization of the eye and skin irritant benzalkonium chloride using UVC radiation

Purpose Benzalkonium chloride (BAK) is a widely used disinfectant and preservative which is effective against a wide range of viruses (e.g. SARS-CoV and SARS-CoV-2), bacteria and fungi. However, it is toxic to the eye and skin. This study investigated the neutralization of BAK using ultraviolet C (UVC) radiation as an effort to reduce BAK toxicity potential. Methods BAK solutions were irradiated with a germicidal UVC lamp at various doses. Human corneal epithelial cells (HCEC) were then exposed to the UVC-irradiated BAK solutions for 5 minutes. After exposure, the cultures were assessed for metabolic activity using PrestoBlue; for cell viability using confocal microscopy with viability dyes; and for tight junction proteins using immunofluorescence staining for zonula occludens (ZO)-1. Results UVC radiation reduced BAK toxicity on cell metabolic activity in a dose-dependent manner. When the solution depth of BAK was 1.7 mm, the UVC doses needed to completely neutralize the toxicity of BAK 0.005% and 0.01% were 2.093 J/cm2 and 8.374 J/cm2, respectively. The cultures treated with UVC-neutralized BAK showed similar cell metabolic activity and cell viability to those treated with phosphate buffered saline (PBS) (p = 0.806 ∼ 1.000). The expression of ZO-1 was greatly disturbed by untreated BAK; in contrast, ZO-1 proteins were well maintained after exposure to UVC-neutralized BAK. Conclusions Our study demonstrates that the cell toxicity of BAK can be neutralized by UVC radiation, which provides a unique way of detoxifying BAK residues. This finding may be of great value in utilizing the antimicrobial efficacy of BAK (e.g. fighting against SARS-CoV-2) while minimizing its potential hazards to human health and the environment.

Low-cost device for active saliva droplet filtration and pathogen inactivation

This work presents a device capable of performing sanitization in environments using an electrostatic filter and ultraviolet light. Recognized techniques were employed in an innovative and low-cost construction model, like Corona Discharge and UVC germicidal light, using elements of easy acquisition and construction. The device consists of a tube with several electrostatic filters. On one side of the tube, an exhaust fan is installed to collect the air to be disinfected. So the air passes through the tubes with the electrostatic filter, which is responsible for collecting the particles suspended in the passing air, attracting them to the metal surface. Allied with this, UVC lights are also inserted in the structure, ensuring greater effectiveness in decontaminating the air that passes through the tubes. In the posterior side to the exhaust fan, the disinfected air is returned to the original environment. A Fluid dynamics simulation was made to investigate the airflow in a room. Standard strains for antimicrobial susceptibility testing were used for bioaerosols assay. The result is a low-cost equipment with great potential to deactivate several kinds of viruses, most especially the Sars-CoV-2 (Coronavirus), that is the main responsible for the global health crisis, designed to be used indoors with low ventilation.

PROTÓTIPO DE UMA CAMARA DE RADIAÇÃO UV-C PARA DESINFECÇÃO DE OBJETOS

Hospitals use germicidal lamps at ultraviolet wavelengths (UV-C -254 nm) to sterilize equipment, water and the environment in operating rooms. The food and medicine industries use them to disinfect various types of products, containers and packaging. Thistechnology is currently being used to disinfect environments, medical and hospital equipment and protective equipment in common use in the face of the current COVID-19 pandemic. In view of the UV-C applications to perform sterilization of environments andobjects, this project involves the development of a prototype using a hardware electronic prototyping platform of a chamber with portable UV lamps for disinfecting objectives. This prototype consists of a hardware module and a software module. In the hardware module, the necessary components for the assembly of the physical system were evaluated, as well as its basic functions, such as the activation of lamps and safety devices, while in the software module, the timing system, the activation and shutdown control were developed. of the lamps, the user interface and security, the exposure to radiation through a magnetic reed switch sensor to check the state of the door.

Enhancing Air Quality for Embedded Hospital Germicidal Lamps

The indoor air of a hospital is always full of bacteria and viruses due to patients with different diseases. These bacteria and viruses could be highly infectious to the people in the hospital irrespective of their health conditions, and could be hazardous to the patients, their care takers, and hospital staff. Thus, keeping a good hospital air quality is very essential to the operation of the hospital. This study aims at enhancing ventilation of the interior lighting of hospitals with germicidal capabilities. Air disinfection is accomplished by adding the specially designed disinfecting filters and fans to existing embedded lamps in the hospitals. The embedded lamp has a square shape of 601 mm in width and 112 mm in thickness. In the design stage, the air flow inside the embedded lamp with the added filters and fans was investigated by numerical simulation using a computational fluid dynamics (CFD) tool. Three designs, referred to as Types 1, 2, and 3, were evaluated using steady-state CFD flow simulations. The ventilation rate of the Type 1 design was about 251.9 CMH, and 348.3 CMH for the Type 2 design by increasing the fan outlet area. However, even though the ventilation was increased by 34%, the flow field of the Type 2 design was not uniform, resulting in flows being circulated around the side locations. Thus, the Type 3 design further treats this aspect by streamlining the outlet geometry and adding flow guiding vanes to reduce flow resistance and flow unsteadiness; the corresponding air ventilation rate reached 376.3 CMH. Hence, the Type 3 design was fabricated and tested. The test results confirm that the design not only has a higher ventilation rate but also operates under a smaller pressure drop, thus accomplishing the goal of providing good air quality in the hospital environment efficiently. Moreover, the associated flow noise is reduced by about 8 dBA. Hence, both an increase in the air ventilation rate and a reduction of noise are achieved simultaneously by the present method.

Photokeratitis following exposure to germicidal ultraviolet lamps during the COVID pandemic

Twelve patients presented with symptoms of pain, redness, watering, and photophobia following exposure to germicidal ultraviolet (UV) lamp. Anterior segment examination showed varying degrees of ciliary congestion and superficial corneal punctate epithelial erosions in all patients. Diagnosis of post-UV photokeratitis was made. Patients were treated with topical antibiotics and artificial lubricating drops. All patients were symptom free 1 week following presentation. The use of standard protective gear and closely following manufacturer guidelines can prevent such complications.

Exhaust unit and stamping machine

A five-lamp exhaust unit and a semi-automatic stamping machine for the production of germicidal ultraviolet lamps are described. Studies have shown that the introduction of this equipment makes it possible to increase the efficiency of the production of bactericidal ultraviolet lamps. These lamps ensure the fulfillment of sanitary and epidemiological requirements for water and air in rooms, multiple reducing the concentration of microorganisms in the air environment. It leads to the relevance of this topic, especially in the context of the COVID-2019 coronavirus pandemic. Keywords assembly; exhaust unit; electrode; filling; amalgam; tapping; stamping, machine

Alternative to High Pressure Mercury Vapor Lamp for Photo Induced Fluorescence Analytical Methods; Application to the Determination of Pesticides in Water.

The photo-induced fluorescence method is often applied to determine non-native fluorescent compounds. It typically uses UV irradiation from a high pressure mercury vapor discharge lamp to create photo-induced fluorescent compounds, which are then quantified by fluorescence spectroscopy. However, these mercury lamps require a high-voltage power supply and may accidentally induce electric shocks and the release of mercury vapors. As an alternative, we have evaluated in this technical note new UV-C germicidal lamps. These lamps exhibit a higher power at 254 nm and allowed us to obtain a far greater amount of photo-induced compounds in a shorter time. For the first time, this new irradiation system has been applied for the determination of pesticides in water and has shown a significant increase in the method sensitivity. These good results allowed us to conclude that the new UV-C lamps are a relevant alternative to high pressure mercury vapor discharge lamps for use with photo induced fluorescent methods.

Design of powered air purifying respirator used for healthcare workers in isolation room

From December 2019, the COVID-19 outbreak has rapidly spread throughout the whole world and become a devastating infectious diseases, with the risk of cross infection quickly and no drug treatment is available. Some countries have been facing shortage of medical equipment, which leads to millions of deaths and may put healthcare workers at risk of infection when they caring for patients sicked with COVID-19 in isolation room, so need to ensure their occupational health and safety. In order to solve this problem, the paper presents a design of Powered Air Purifying Respirator (PAPR) to prevent cross-contamination COVID-19 infection in isolation room, protect for occupational health and safety of healthcare workers. That is specialized equipment for medical industry using ambient air as energy source to operate, the device removes contaminated air through the filters and UVC germicidal light bulbs, then provides clean air to the user's face through blower. It creates continuous positive pressure, and this positive pressure prevents outside contaminated air to a face, but it must be com ply with the safety standards of NIOSH. Especially, this design can be used in case of an emergency, lack of medical supplies and equipment because it can be connected to commercially available masks through a hose connector and a respiratory hose. In case the device does not work or out of battery, a mask accompanied by a hose connector can be connected to the breathing tubes placed in isolation room, all these breathing tubes use clean air from heating, ventilating, and air conditioning (HVAC) of isolation room. Simulations and experiments are attached below to compare the difference between ideal parameters and actual results. From which to draw conclusions and development directions of the research.

UV-Photokeratitis Associated with Germicidal Lamps Purchased during the COVID-19 Pandemic

ABSTRACT Purpose To report photokeratitis caused by the improper use of germicidal lamps purchased during the COVID-19 pandemic. Methods Case series. Results Seven patients presented with acute ocular surface pain after exposure to UV-emitting germicidal lamps. Visual acuity was 20/30 or better in 13 of 14 eyes (93%). Anterior segment examination revealed varying degrees of conjunctival injection and diffusely distributed punctate epithelial erosions (PEEs) in every patient. No intraocular inflammation was identified across the cohort and all fundus examinations were normal. Treatment varied by provider and included artificial tears alone or in combination with antibiotic ointments and/or topical steroids. Five patients were followed via telehealth, one patient returned for an in-office visit, and one patient was lost to follow-up. Five of six patients endorsed complete resolution of symptoms within 2–3 days. Conclusions Patients should follow manufacturer recommendations when using UV-emitting germicidal lamps and avoid direct exposure to the ocular surface.

Photocatalytic Reactivity of Carbon–Nitrogen–Sulfur-Doped TiO2 Upconversion Phosphor Composites

Sol–gel synthesized N-doped and carbon–nitrogen–sulfur (CNS)-doped TiO2 solutions were deposited on upconversion phosphor using a dip coating method. Scanning electron microscopy (SEM) imaging showed that there was a change in the morphology of TiO2 coated on NaYF4:Yb,Er from spherical to nanorods caused by additional urea and thiourea doping reagents. Fourier transform infrared (FTIR) spectroscopy further verified the existence of nitrate–hyponitrite, carboxylate, and SO42− because of the doping effect. NaYF4:Yb,Er composites coated with N- and CNS-doped TiO2 exhibited a slight shift of UV-Vis spectra towards the visible light region. Photodecomposition of methylene blue (MB) was evaluated under 254 nm germicidal lamps and a 300 W Xe lamp with UV/Vis cut off filters. The photodegradation of toluene was evaluated on TiO2/NaYF4:Yb,Er and CNS-doped TiO2/NaYF4:Yb,Er samples under UV light illumination. The photocatalytic reactivity with CNS-doped TiO2/NaYF4:Yb,Er surpassed that of the undoped TiO2/NaYF4:Yb,Er for the MB solution and toluene. Photocatalytic activity is increased by CNS doping of TiO2, which improves light sensitization as a result of band gap narrowing due to impurity sites.

The ultraviolet offense: Germicidal UV lamps destroy vicious viruses. New tech might put them many more places without harming humans

WALK INTO THE CAMBRIDGE, ONT., OFFICE of health-care equipment company PrescientX and you probably wouldn't suspect you're entering one of the most sanitary places in North America. • In this otherwise-ordinary Toronto-area office suite, you can disinfect your keys, phone, and other portables at the reception area's ultraviolet-sterilization stand. In cooler months, the air you breathe is cleansed of mold and bacteria in UV-sterilized heating units as well as blasted by UV fixtures in the office air ducts to eliminate viruses. In-room UV fixtures pointing at the ceiling disinfect the air, while other UV lights that turn on only when no one's in the room zap pathogens on desks, keyboards, and high-touch surfaces in bathrooms and work spaces. • The office, says PrescientX founder and CEO Barry Hunt, represents a possible future in which pandemics like COVID-19 are more commonplace — but in which germicidal ultraviolet light is one of the most potent weapons we have to face them down.

Desinfección mediante el uso de luz UV-C germicida en diferentes medios como estrategia preventiva ante la COVID-19

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

Air Disinfection by UV Germicidal Radiation

Since 2005, in our country, the use of UV germicidal radiation for disinfection of the indoor air environment is regulated by the guidance of R3.5.1904–64 (as the recommendations). This radiation is dangerous for humans: skin and especially the eyes are affected. It is necessary to use closed irradiators (recirculators) with germicidal lamps, and not open ones, the radiation of which covers the entire volume of the room in order to avoid exposure of people during disinfection of indoor air. This requires taking people from the premises and observing all relevant safety measures. Unfortunately, in practice, there may occur, accidentally or out of ignorance of the rules for open irradiators operating by personnel, violations of safety rules leading to grave consequences. To eliminate such violations, it is necessary to increase the level of knowledge of staff, but there is no special educational and technical literature. This article attempts to fill this gap.

Fight Against COVID-19: ARCI's Technologies for Disinfection.

COVID-19 (SARS-CoV-2) is causing a huge concern to the global population due to its highly contagious properties. The SARS-CoV-2 is a new variant in the coronavirus family. The world is focussing on several methods to battle against this novel corona virus, including control of its spread. In this context, ARCI has quickly made efforts to develop disinfection systems including a UVC-based disinfection trolley, honeycomb air heater and a fogging chamber using UVC germicidal lamps, dry heat sterilization and HOCl-based chemical disinfectant to provide rapid and effective inactivation of microorganisms causing the pandemic. These systems have been successfully deployed at different hospitals for their validation.

Long-term Effects of 222-nm ultraviolet radiation C SterilizingLamps on Mice Susceptible to Ultraviolet Radiation.

Germicidal lamps that emit primarily 254 nm ultraviolet radiation (UV) are routinely utilized for surface sterilization but cannot be used for human skin because they cause genotoxicity. As an alternative, 222‐nm UVC has been reported to exert sterilizing ability comparable to that of 254‐nm UVC without producing cyclobutane pyrimidine dimers (CPDs), the major DNA lesions caused by UV. However, there has been no clear evidence for safety in chronic exposure to skin, particularly with respect to carcinogenesis. We therefore investigated the long‐term effects of 222‐nm UVC on skin using a highly photocarcinogenic phenotype mice that lack xeroderma pigmentosum complementation group A (Xpa‐) gene, which is involved in repairing of CPDs. CPDs formation was recognized only uppermost layer of epidermis even with high dose of 222‐nm UVC exposure. No tumors were observed in Xpa‐knockout mice and wild‐type mice by repetitive irradiation with 222‐nm UVC, using a protocol which had shown to produce tumor in Xpa‐knockout mice irradiated with broad‐band UVB. Furthermore, erythema and ear swelling were not observed in both genotype mice following 222‐nm UVC exposure. Our data suggest that 222‐nm UVC lamps can be safely used for sterilizing human skin as far as the perspective of skin cancer development.