Ultraviolet Germicidal Irradiation Effectiveness Research Articles

Ultraviolet germicidal irradiation is effective against SARS-CoV-2 in contaminated makeup powder and lipstick

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.

Effect of ultraviolet germicidal irradiation of the air on the incidence of upper respiratory tract infections in kittens in a nursery.

To evaluate the effect of UV germicidal irradiation of the air on the incidence of upper respiratory tract infections (URIs) in kittens in a nursery. 4- to 8-week-old kittens admitted to a kitten nursery in 2016 and 2018. 2 UV germicidal irradiation systems (1 within the heating, ventilation, and air conditioning system and 1 attached to the ceiling) were installed in a kitten nursery. Data were collected on the number of kittens in which a URI was diagnosed by means of a physical examination. The incidence of URIs was compared between 2016, when no UV systems were used, and 2018, when the UV systems were used. The overall incidence of URIs in 2016 was 12.4 cases/100 kitten admissions and in 2018 was 1.6 cases/100 kitten admissions, a significant decrease of 87.1% between the years. A significant reduction in the incidence of URIs in kittens in a nursery was noted when the UV germicidal irradiation systems were used. Therefore, airborne transmission of feline respiratory pathogens may be more important than has been previously recognized. Ultraviolet germicidal irradiation systems that disinfect the air may be an effective adjunct to standard infection prevention and control protocols in reducing the risk of the transmission of respiratory pathogens among kittens in nurseries and shelters. However, additional studies are needed to confirm the findings reported here.

Forcing Seasonality of Influenza-like Epidemics with Daily Solar Resonance.

SummarySeasonality of acute viral respiratory diseases is a well-known and yet not fully understood phenomenon. Several models have been proposed to explain the regularity of yearly recurring outbreaks and the phase differences observed at different latitudes on the Earth. Such models consider known internal causes, primarily the periodic emergence of new virus variants that evade the host immune response. Yet, this alone is generally unable to explain the regularity of recurrences and the observed phase differences.Here we show that seasonality of viral respiratory diseases, as well as its distribution with latitude on the Earth, can be fully explained by the virucidal properties of UV-B and UV-A solar photons through a daily, minute-scale, resonant forcing mechanism. Such an induced periodicity can last, virtually unperturbed, from tens to hundreds of cycles, and even in the presence of internal dynamics (host's loss of immunity) much slower than seasonal will, on a long period, generate seasonal oscillations.

Ultraviolet germicidal irradiation for filtering facepiece respirators disinfection to facilitate reuse during COVID-19 pandemic: A review.

To review the effect of ultraviolet germicidal irradiation (UVGI) as a disinfection method for filtering facepiece respirators (FFRs) to facilitate reuse during COVID-19 pandemic. Systematic review of the research concerning UVGI for FFRs disinfection to facilitate reuse (also termed limited reuse) during respiratory infectious diseases where aerosol transmission is considered possible. UVGI is one possible method for respiratory disinfection to facilitate the reuse of dwindling supplies. Appropriate dose UVGI exposition could provide enough energy to effectively decontaminate respiratory viral agents and maintain respirator's integrity for reuse. There was not currently sufficient research evidence on the effect of UVGI to inactivate coronaviruses SARS-CoV-2, and the practical application of UVGI is still unclear. . Appropriate dose UVGI exposition could provide enough energy to effectively decontaminate respiratory viral agents and maintain respirator's integrity for reuse. Further evidence concerning UVGI as a decontamination technique specifically for SARS-CoV-2 isneeded.

PMD49 - Cost Effectiveness of Ultra-Violet Germicidal Irradiation in Canadian Health Region

PMD49 - Cost Effectiveness of Ultra-Violet Germicidal Irradiation in Canadian Health Region

Ultraviolet germicidal irradiation in tap water contaminated by Aspergillus spp.

SummaryWe investigated the effect of ultraviolet germicidal irradiation (UVI) from a low-pressure mercury lamp on several pathogenic Aspergillus spp. including A. flavipes, A. flavus, A. fumigatus, A. glaucus, A. nidulans, A. niger, A. terreus, A. ustus and A. versicolor suspended in tap water under laboratory-scale conditions. It was shown that within 10 s of exposure, time species such as A. glaucus, A. niudulans and A. ustus were completely inactivated, while 40 s were needed for the elimination of all the species tested. A. flavus and A. niger were found to be less susceptible than other species. Based on these results we conclude that UV disinfection could effectively inactivate Aspergillus spp. in tap water. Such disinfection could be used to reduce potential exposure of high-risk patients to fungal aerosols, particularly in hospital settings, where point-of-use (POU) UV light devices could be installed to provide safe water at a very low cost.

Effectiveness of an ultraviolet germicidal irradiation system in enhancing cooling coil energy performance in a hot and humid climate

Biological fouling (biofouling) on wetted cooling coil surfaces decreases heat transfer efficiency, increases air-side flow resistance and may eventually lead to more energy consumption by fans and chiller plants. Applying ultraviolet germicidal irradiation (UVGI) systems in air handling units (AHUs) has the potential to clean coils, improve coil performance and save energy. In this study, the effectiveness of a coil irradiation system in improving coil performance and saving energy was investigated through a field test in a hot and humid climate. A commercially available coil irradiation system was installed downstream of a cooling coil in a variable air volume (VAV) AHU. The duration of the field test was 14 months, with four months before UVGI intervention and 10 months after UVGI intervention. The effectiveness of UVGI was evaluated via a “before UV” and “after UV” comparison of coil performance. The coil overall thermal conductance increased by 10% and the pressure drop decreased by 13%, with the improvement being most rapid over the first month after UVGI intervention. Fan energy use fell by 9% over the ten months of UVGI operation. Savings in fan energy were 39% greater than the energy used by the UV lamps.

Upper room UVGI effectiveness with dispersed pathogens at different droplet sizes in spaces conditioned by chilled ceiling and mixed displacement ventilation system

This paper investigates by modeling and experimentation the dispersion of bacteria and performance of Upper Room Ultraviolet Germicidal Irradiation (UVGI) in spaces conditioned by combined chilled ceiling (CC) and mixed displacement ventilation (DV) system. The effects of gravitational settling and deposition were taken into account in mathematical modeling to reasonably simulate the transport of pathogen via expiratory droplets of all size ranges. The model was experimentally validated with and without the use of UVGI for different ventilation rates. Experiments were conducted in a CC/DV test room with a constant generation of Serratia marcescens, an extremely UV-susceptible microorganism to measure the airborne bacteria concentration in the room air and quantify the bacteria deposition on horizontal surfaces. The experimental bacteria colony forming units (CFU) count was used to validate a CFD model developed to predict the deposition of pathogen carriers. The mathematical model was then substantiated using the CFD predictions of pathogen concentration in the space for large carrying particles. The validated mathematical model was then used to study the effect of pathogen-carrying particle sizes on the microbiological indoor air quality. Results showed that the droplet size affects the value of maximal bacteria concentration and the height at which it occurs. Moreover, the UV disinfection rate achieved in the upper zone decreases from 88% to 78% when the size of pathogen-carrying particles increases from 2.5 μm to 20 μm meaning that greater percentage of bacteria are removed by deposition when bacteria is carried by large particles.

Improving the effectiveness of ultraviolet germicidal irradiation through reflective wall coatings: Experimental and modeling based assessments

Experimental and modeling based assessments of employing reflective wall coatings towards improving the effectiveness of ultraviolet germicidal irradiation in unoccupied hospital rooms were carried out. Measurements of incident radiative fluxes on different surfaces were made in a control room as well as a room whose walls were painted with a nanostructured UV-C reflective wall coating. Employing the reflective paint resulted in up to a 20% increase in the incident radiative fluxes on some surfaces that were directly exposed to the radiation and nearly a 10-fold increase on surfaces that were not directly exposed. Spatially and directionally well-resolved simulations of radiative transfer within the rooms were carried out employing the finite volume radiation model. The measured enhancement in radiative fluxes predicted numerically agreed in general with experimental observations. The volume-averaged incident radiation increased by 60% in the presence of UV reflective walls. Ray effects or the preferential streaming of radiation in the numerical calculations was more pronounced in the control room and was minimized by increasing the angular resolution of the calculations even further. However in the room with UV reflective walls, the diffuse reflections caused the intensity distributions to become more isotropic and minimized the impacts of ray effects.

Effects of ultraviolet germicidal irradiation and swirling motion on airborneStaphylococcus aureus,Pseudomonas aeruginosaandLegionella pneumophilaunder various relative humidities

Staphylococcus aureus, Pseudomonas aeruginosa, and Legionella pneumophila have been detected in indoor air and linked to human infection. It is essential to adopt control methods to inactivate airborne pathogens. By passing bioaerosols horizontally into a UV device at two flow rates (Qs) and moving cells around a central UVC lamp at relative humidity (RH) of 12.7-16.7%, 58.7-59.6%, and 87.3-90%, the effects of swirling motion and 254-nm ultraviolet germicidal irradiation (UVGI) against bioaerosols were assessed under UV-off and UV-on settings, respectively. An inverse relationship between RH and UVGI effectiveness was observed for every test bioaerosol (r = -0.74 ∼ -0.81, P < 0.0001). Increased UV resistance with RH is likely associated with the hygroscopicity of bioaerosols, evident by increased aerodynamic diameters at high RH (P < 0.05). UVGI effectiveness was significantly increased with decreasing Q (P < 0.0001). Moreover, P. aeruginosa was the most susceptible to UVGI, while the greatest UV resistance occurred in L. pneumophila at low RH and S. aureus at medium and high RH (P < 0.05). Results of UV off show P. aeruginosa and L. pneumophila were more sensitive to air-swirling motion than S. aureus (P < 0.05). Overall, test bioaerosols were reduced by 1.7-4.9 and 0.2-1.7 log units because of the UVGI and swirling movement, respectively. The studied UV device, with a combination of swirling motion and UVGI, is effective to inactivate airborne S. aureus, P. aeruginosa, and L. pneumophila. This study also explores the factors governing the UVGI and swirling motion against infectious bioaerosols. With understanding the environmental and operational parameters, the studied UV device has the potential to be installed indoors where people are simultaneously present, for example, hospital wards and nursing homes, to prevent the humans from acquiring infectious diseases.

Development of a Fungal Biosensor for Field Verifying the Surface Disinfection of Ultraviolet Germicidal Irradiation Systems for Air Handling Units

This study developed a fungal biosensor to verify the germicidal effect of ultraviolet germicidal irradiation (UVGI) systems in the field from a biosensor originally developed to assess indoor climate. A UVC ray was irradiated on the fungal spores of the biosensors at various doses, and the differences in hyphal length after subsequent incubation were observed to verify the susceptibility of the fungal biosensor to C-band ultraviolet (UVC). The results showed reasonable correlations between UVC dosage and hyphal length. These fungal biosensors were thereafter attached to the coil and the drain pan of an air handling unit with a UVGI system installed and exposed to UVC for 1 h to test the effectiveness of the biosensors on the UVGI systems in the field. The hyphal lengths observed after incubation corresponded with UVC doses of 468–1620 J·m−2 at each sampling point as shown in the previous susceptibility experiments. The extended experiments to confirm the susceptibility of the fungal spores showed that the spores were more sensitive to UVC ray than those of the fungal biosensor and had similar susceptibility to the same UVC doses even at different UVC intensities.

Effect of Turbulence on Ultraviolet Germicidal Irradiation

It is shown that in ultraviolet germicidal irradiation (UVGI) systems for air disinfection, where turbulence completely mixes the flow in the directions perpendicular to the net flow direction, turbulence can also act to reduce the effectiveness of the system. This occurs when the longitudinal diffusion coefficient resulting from the turbulence is large enough to reduce the effective transit time of the air through the ultraviolet irradiation zone. At the same time, depending on the radiation fluence, UV kill rate parameter, diffusion coefficient, and flow rate, the longitudinal turbulent diffusion can also increase the effectiveness of the UVGI system. The appropriate combination of parameters for ascertaining whether turbulence reduces or increases UVGI effectiveness is derived.

Inactivation of Viruses on Surfaces by Ultraviolet Germicidal Irradiation

In many outbreaks caused by viruses, the transmission of the agents can occur through contaminated environmental surfaces. Because of the increasing incidence of viral infections, there is a need to evaluate novel engineering control methods for inactivation of viruses on surfaces. Ultraviolet germicidal irradiation (UVGI) is considered a promising method to inactivate viruses. This study evaluated UVGI effectiveness for viruses on the surface of gelatin-based medium in a UV exposure chamber. The effects of UV dose, viral nucleic acid type (single-stranded RNA, ssRNA; single-stranded DNA, ssDNA; double-stranded RNA, dsRNA; and double-stranded DNA, dsDNA), and relative humidity on the virus survival fraction were investigated. For 90% viral reduction, the UV dose was 1.32 to 3.20 mJ/cm2 for ssRNA, 2.50 to to 4.47 mJ/cm2 for ssDNA, 3.80 to 5.36 mJ/cm2 for dsRNA, and 7.70 to 8.13 mJ/cm2 for dsDNA. For all four tested viruses, the UV dose for 99% viral reduction was 2 times higher than those for 90% viral reduction. Viruses on a surface with single-stranded nucleic acid (ssRNA and ssDNA) were more susceptible to UV inactivation than viruses with double-stranded nucleic acid (dsRNA and dsDNA). For the same viral reduction, the UV dose at 85% relative humidity (RH) was higher than that at 55% RH. In summary, results showed that UVGI was an effective method for inactivation of viruses on surfaces.

Biological Monitoring of Ultraviolet Germicidal Irradiation in a Biosafety Level 3 Laboratory

Ultraviolet germicidal irradiation (UVGI) lamps are used in biological safety cabinets and laboratory containment rooms as methods of surface decontamination. Although some organizations have discouraged the use of UVGI for disinfection, many scientists continue to request this method. The objective of this study was to assess the reliability of using UVGI produced from UV ceiling lamps as an effective method to decrease microbial agent contamination from floor surfaces in a biosafety level 3 laboratory. Actively growing Bacillus cereus and B. anthracis vegetative cells or spores (Sterne strain-Veterinary Vaccine Formula) were used as biological indicators to assess UVGI effects within the containment laboratory. Studies were conducted using UVGI exposure times ranging from 15 minutes to 2 hours with varying inoculums ranging from 10 3 to 10 9 colony-forming unit per sample. Later in the study an UVGI radiometer was used to determine the UVGI intensity and to measure the correlation between the biological indicator results and mechanical instrument data. Study results showed that ceilingmounted UVGI lamps were effective in reducing the viability of both B. cereus and B. anthracis vegetative cells and spores after a minimum UVGI exposure time of 1 hour at an intensity as low as 8 uW/cm 2 . Additionally, an UVGI radiometer could be used to determine UVGI effectiveness and a UVGI intensity of 8 uW/cm 2 to 42 uW/cm 2 corresponded with the increased disinfection observed.

Inactivation of Virus-Containing Aerosols by Ultraviolet Germicidal Irradiation

The increasing incidence of infectious diseases has prompted the application of Ultraviolet Germicidal Irradiation (UVGI) for the inactivation of viruses. This study evaluates UVGI effectiveness fo...

Ultraviolet germicidal irradiation disinfection of Stachybotrys chartarum

The ultraviolet germicidal irradiation (UVGI) dose necessary to inactivate fungal spores on an agar surface and the efficacy of UVGI were determined for cultures of Stachybotrys chartarum (ATCC 208877). This study employed a UVGI testing unit consisting of four chambers with a 9-W, Phillips, low pressure, mercury UVGI lamp in each chamber. The testing unit's apertures were adjusted to provide 50, 100, 150, and 200 microW/cm2 of uniform flux to the Petri dish surfaces, resulting in a total UVGI surface dose ranging from 12 to 144 mJ/cm2. The UVGI dose necessary to inactivate 90% of the S. chartarum was greater than the maximum dose of 144 mJ/cm2 evaluated in this study. While UVGI has been used to inactivate several strains of culturable fungal spores, S. chartarum was not susceptible to an appropriate dose of UVGI. The results of this study may not correlate directly to the effect of UVGI on airborne fungal spores. However, they indicate that current technology may not be efficacious as a supplement to ventilation unless it can provide higher doses of UVGI to kill spores, such as S. chartarum, traveling through the irradiated zone.

Erratum: Control Effectiveness of Ultraviolet Germicidal Irradiation on Bioaerosols

Click to increase image sizeClick to decrease image sizeThis article refers to:Control Effectiveness of Ultraviolet Germicidal Irradiation on BioaerosolsUltraviolet Germicidal Irradiation and Titanium Dioxide Photocatalyst for Controlling Legionella pneumophila

Ultraviolet germicidal irradiation of office ventilation systems reduces work-related mucosal and respiratory symptoms*1

What is the effect of ultraviolet germicidal irradiation (UVGI) in office ventilation systems on worker's health and wellbeing? Double blind multiple crossover trial. Ultraviolet germicidal irradiation (UVGI) lights significantly reduced the incidence of overall work-related symptoms (14% of symptoms only reported when UVGI on vs. 18% symptoms only reported only when UVGI off; OR 0.8, 95% CI 0.7 to 0.99). UVGI significantly reduced work-related mucosal and respiratory symptoms but not systemic or musculoskeletal symptoms (OR for mucosal symptoms 0.7, 95% CI 0.6 to 0.9; OR for respiratory symptoms 0.6, 95% CI 0.4 to 0.9; OR for systemic symptoms 1.1, 95% CI 0.9 to 1.3; OR for musculoskeletal symptoms 0.8, 95% CI 0.6 to 1.1). UVGI reduced microbial and endotoxin concentrations on irradiated surfaces within ventilation systems by 99% (95% CI 67% to 100%). UVGI may be a cost-effective method of alleviating work-related symptoms caused by microbial contamination of office ventilation systems.

Ultraviolet germicidal irradiation of office ventilation systems reduces work-related mucosal and respiratory symptoms

Question What is the effect of ultraviolet germicidal irradiation (UVGI) in office ventilation systems on worker's health and wellbeing? Study design Double blind multiple crossover trial. Main results Ultraviolet germicidal irradiation (UVGI) lights significantly reduced the incidence of overall work-related symptoms (14% of symptoms only reported when UVGI on vs. 18% symptoms only reported only when UVGI off; OR 0.8, 95% CI 0.7 to 0.99). UVGI significantly reduced work-related mucosal and respiratory symptoms but not systemic or musculoskeletal symptoms (OR for mucosal symptoms 0.7, 95% CI 0.6 to 0.9; OR for respiratory symptoms 0.6, 95% CI 0.4 to 0.9; OR for systemic symptoms 1.1, 95% CI 0.9 to 1.3; OR for musculoskeletal symptoms 0.8, 95% CI 0.6 to 1.1). UVGI reduced microbial and endotoxin concentrations on irradiated surfaces within ventilation systems by 99% (95% CI 67% to 100%). Authors’ conclusions UVGI may be a cost-effective method of alleviating work-related symptoms caused by microbial contamination of office ventilation systems.

Disinfection of selected Aspergillus spp. using ultraviolet germicidal irradiation.

The efficacy of ultraviolet germicidal irradiation (UVGI) and the UVGI dose necessary to inactivate fungal spores on an agar surface for cultures of Aspergillus flavus and Aspergillus fumigatus were determined. A four-chambered UVGI testing unit with a 9-W, Phillips, low pressure, mercury UVGI lamp in each chamber was used in this study. An aperture was adjusted to provide 50, 100, 150, and 200 micro W/cm2 of uniform flux to the surfaces of the Petri dish, resulting in a total UVGI dose to the surface of the Petri dishes ranging from 12 to 96 mJ/cm2. The UVGI dose necessary to inactivate 90% of the A. flavus and A. fumigatus was 35 and 54 mJ/cm2, respectively. UVGI can be used to inactivate culturable fungal spores. Aspergillus flavus was more susceptible than A. fumigatus to UVGI. These results may not be directly correlated to the effect of UVGI on airborne fungal spores, but they indicate that current technology may not be efficacious as a supplement to ventilation unless it can provide higher doses of UVGI to kill spores traveling through the irradiated zone.