Ultraviolet C Research Articles

Path and Trajectory Planning for UV-C Disinfection Robots

Ultraviolet-C (UV-C) disinfection has been known for long, but its use with robotics is quite new, mainly motivated by the recent coronavirus disease pandemics (COVID-19). In UV-C disinfection, application of the right dose to target surfaces is fundamental to ensure proper disinfection. Hence a common goal is to provide a proper motion plan that ensures effective disinfection. In this paper, we provide a generic framework that generates a shortest path and the corresponding trajectory that ensures effective disinfection while optimizing different cost functions, and then experimentally verify it using a differential drive mobile robot. The trajectories generated by the proposed framework comply with kinodynamic constraints of the robot carrying the UV-C source. We also study non-uniform illumination and present a novel cost function that aims to decrease excessive illumination, in order to reduce UV-C damage of the surfaces. Additionally, we analyze the effect of height of line sources, which can change effectiveness and speed of disinfection considerably.

Low-power blue LED and red laser effects on plasmid DNA, survival, and photolyase mRNA levels in Escherichia coli cultures

Low-power lasers and light-emitting diodes (LEDs) are used for photobiomodulation therapy, but the photobiological effects on DNA repair mechanisms in bacteria cells are disputed yet. This work aimed to evaluate the induction of DNA damages in plasmids, bacterial survival and proliferation, and photolyase mRNA levels in E. coli cultures exposed to low-power blue LED and red laser, followed by ultraviolet c (UVC) radiation. Aliquots of pUC19 plasmids and E. coli C600 cultures were exposed to low-power blue LED (470 nm) and red laser (658 nm) at different fluences. Other E. coli C600 cultures were exposed to UVC radiation after exposure to low-power blue LED and red laser. After irradiations, plasmids were submitted to agarose gel electrophoresis to evaluate DNA damage, bacterial cultures were spread onto Petri dishes content rich medium and incubated to evaluate bacterial survival and proliferation, and photolyase mRNA levels in bacterial cells were evaluated by reverse transcription-quantitative polymerase chain reaction. The results suggest that exposure to blue and red lights emitted from low-power LEDs and lasers does not cause DNA strand breaks in bacterial plasmids and does not alter the survival and mRNA levels from photolyase gene in E. coli cells, but increases bacterial survival and proliferation in E. coli cultures exposed to UVC radiation depending on LED and laser fluences.

Multifilament Collagen Fiber Bundles with Tendon-like Structure and Mechanical Performance.

Collagen multifilament bundles comprised of thousands of monofilaments are prepared by multipin contact drawing of an entangled polymer solution consisting of collagen and poly(ethylene oxide) (PEO). The multifilament bundles are hydrated in graded concentrations of PEO and phosphate buffered saline (PBS) to promote assembly of collagen fibrils within each monofilament while preserving the structure of the multifilament bundle. Multiscale structural characterization reveals that the hydrated multifilament bundle contains properly folded collagen molecules packed in collagen fibrils containing microfibrils, staggered by exactly one-sixth of the microfibril D-band spacing to produce a periodicity of 11nm. Sequence analysis predicts that in this structure, phenylalanine residues are close enough within and between microfibrils to become ultraviolet C (UVC) crosslinked. In agreement with this analysis, the ultimate tensile strength (UTS) and Young's modulus of the hydrated collagen multifilament bundles crosslinked by UVC radiation increase nonlinearly with total UVC energy to reach values in the range of native tendons without damage to the collagen molecules. This fabrication method recapitulates the structure of a tendon across multiple length scales and offers tunability in tensile properties using only collagen molecules and no other chemical additives in addition to PEO, which is almost entirely removed during the hydration process.

A do-it-yourself test protocol using commercial Bacillus atrophaeus spores to evaluate the effectiveness of ultraviolet-C light room-decontamination devices.

We developed a do-it-yourself test protocol using commercial Bacillus atrophaeus spores to assess the efficacy of ultraviolet-C (UV-C) light room-decontamination devices. Overall, 4 UV-C devices reduced B. atrophaeus by ≥3 log10 colony-forming units in 10 minutes, whereas a smaller device required 60 minutes. Of 10 in-use devices, only 1 was ineffective.

Different biological effects of exposure to far-UVC (222nm) and near-UVC (254nm) irradiation.

Ultraviolet C (UVC) light has long been used as a sterilizing agent, primarily through devices that emit at 254nm. Depending on the dose and duration of exposure, UV 254nm can cause erythema and photokeratitis and potentially cause skin cancer since it directly modifies nitrogenated nucleic acid bases. Filtered KrCl excimer lamps (emitting mainly at 222nm) have emerged as safer germicidal tools and have even been proposed as devices to sterilize surgical wounds. All the studies that showed the safety of 222nm analyzed cell number and viability, erythema generation, epidermal thickening, the formation of genetic lesions such as cyclobutane pyrimidine dimers (CPDs) and pyrimidine-(6-4)-pyrimidone photoproducts (6-4PPs) and cancer-inducing potential. Although nucleic acids can absorb and be modified by both UV 254nm and UV 222nm equally, compared to UV 254nm, UV 222nm is more intensely absorbed by proteins (especially aromatic side chains), causing photooxidation and cross-linking. Here, in addition to analyzing DNA lesion formation, for the first time, we evaluated changes in the proteome and cellular pathways, reactive oxygen species formation, and metalloproteinase (MMP) levels and activity in full-thickness in vitro reconstructed human skin (RHS) exposed to UV 222nm. We also performed the longest (40days) in vivo study of UV 222nm exposure in the HRS/J mouse model at the occupational threshold limit value (TLV) for indirect exposure (25mJ/cm2) and evaluated overall skin morphology, cellular pathological alterations, CPD and 6-4PP formation and MMP-9 activity. Our study showed that processes related to reactive oxygen species and inflammatory responses were more altered by UV 254nm than by UV 222nm. Our chronic in vivo exposure assay using the TLV confirmed that UV 222nm causes minor damage to the skin. However, alterations in pathways related to skin regeneration raise concerns about direct exposure to UV 222nm.

UV-C Based Disinfectant Robot

Abstract: UVC (ultraviolet-C) light has been proven to kill various bacteria and viruses, including the COVID-19-producing virus, which has been discovered to be a powerful disinfectant. Manual UVC disinfection, on the other hand, can be tiresome, time-consuming, and hazardous for human operators. As our senior project, we developed a UVC-based disinfection robot to address these problems. Our robot has been designed to move and clean on its own in a variety of applications including hospitals, schools, and public places. Ultrasonic sensors for navigation and obstacle avoidance, a mobile platform, a UVC light source, and an Arduino microcontroller for communication and control comprise the robot.We conducted a microbiological test to gauge the robot's performance by comparing the number of microbe cells on a surface before and after UVC disinfection. Our findings demonstrated the robot's effectiveness as a disinfection tool by showing that bacterial colonies were reduced by 93.9%. By measuring UVC radiation levels at various angles and at various distances from the light source, we were also able to assess the safety of the robot. Our findings demonstrated that the robot complied with safety requirements for UVC radiation exposure to humans.

Performance and Degradation of Commercial Ultraviolet‐C Light‐Emitting Diodes for Disinfection Purposes

Herein, the reliability of commercial ultraviolet‐C (UV‐C) light‐emitting diodes (LEDs) subjected to constant current stress is reported. Electrical, optical, and spectral analyses are carried out on UV‐C LEDs with an emission peak of 275 nm and a nominal optical power of 12 mW at 100 mA. Degradation tests are carried out at the maximum rated current, the double and at three times the maximum. The LED lifetime is found to be inversely proportional to the third power of the stress current density, indicating that the degradation mechanism might be activated by high‐energy electrons arising from Auger–Meitner recombination. Electrical characterization indicates an increase in defect‐related leakage, whereas the spectral analysis identifies a variation in two emission peaks which can be ascribed to a defect density increase in the active region and the p‐gallium nitride (GaN) layer of the LEDs. A final remark comes from the strong dependence of lifetime on operating current: increasing current to lower the number of LEDs in a system is not an optimized strategy. In fact, this has a substantial impact on system lifetime, thus lowering the total number of permitted disinfections.

The Prophylactic Effect of Vitamin C and Vitamin B12 against Ultraviolet-C-Induced Hepatotoxicity in Male Rats.

Ultraviolet C (UVC) devices are an effective means of disinfecting surfaces and protecting medical tools against various microbes, including coronavirus. Overexposure to UVC can induce oxidative stress, damage the genetic material, and harm biological systems. This study investigated the prophylactic efficacy of vitamin C and B12 against hepatotoxicity in UVC-intoxicated rats. Rats were irradiated with UVC (725.76, 967.68, and 1048.36 J/cm2) for 2 weeks. The rats were pretreated with the aforementioned antioxidants for two months before UVC irradiation. The prophylactic effect of vitamins against UVC hepatotoxicity was evaluated by monitoring the alteration of liver enzyme activities, antioxidant status, apoptotic and inflammatory markers, DNA fragmentation, and histological and ultrastructural alterations. Rats exposed to UVC showed a significant increase in liver enzymes, oxidant-antioxidant balance disruption, and increased hepatic inflammatory markers (TNF-α, IL-1β, iNOS, and IDO-1). Additionally, obvious over-expression of activated caspase-3 protein and DNA fragmentation were detected. Histological and ultrastructural examinations verified the biochemical findings. Co-treatment with vitamins ameliorated the deviated parameters to variable degrees. In conclusion, vitamin C could alleviate UVC-induced hepatotoxicity more than vitamin B12 by diminishing oxidative stress, inflammation, and DNA damage. This study could provide a reference for the clinical practice of vitamin C and B12 as radioprotective for workers in UVC disinfectant areas.

Yeast UPS1 deficiency leads to UVC radiation sensitivity and shortened lifespan.

UPS1/YLR193C of Saccharomyces cerevisiae (S. cerevisiae) encodes a mitochondrial intermembrane space protein. A previous study found that Ups1p is needed for normal mitochondrial morphology and that UPS1 deficiency disrupts the intramitochondrial transport of phosphatidic acid in yeast cells and leads to an altered unfolded protein response and mTORC1 signaling activation. In this paper, we first provide evidence showing that the UPS1 gene is involved in the UVC-induced DNA damage response and aging. We show that UPS1 deficiency leads to sensitivity to ultraviolet C (UVC) radiation and that this effect is accompanied by elevated DNA damage, increased intracellular ROS levels, abnormal mitochondrial respiratoryfunction, an increased early apoptosis rate, and shortened replicative lifespan and chronological lifespan. Moreover, we show that overexpression of the DNA damage-induced checkpoint gene RAD9 effectivelyeliminates the senescence-related defects observed in the UPS1-deficient strain. Collectively, these results suggest a novel role for UPS1 in the UVC-induced DNA damage response and aging.

Investigating the Impacts of UVC Radiation on Natural and Cultured Biofilms: An assessment of Cell Viability.

Biofilms are conglomerates of cells, water, and extracellular polymeric substances which can lead to various functional and financial setbacks. As a result, there has been a drive towards more environmentally friendly antifouling methods, such as the use of ultraviolet C (UVC) radiation. When applying UVC radiation, it is important to understand how frequency, and thus dose, can influence an established biofilm. This study compares the impacts of varying doses of UVC radiation on both a monocultured biofilm consisting of Navicula incerta and field-developed biofilms. Both biofilms were exposed to doses of UVC radiation ranging from 1626.2 mJ/cm2 to 9757.2 mJ/cm2 and then treated with a live/dead assay. When exposed to UVC radiation, the N. incerta biofilms demonstrated a significant reduction in cell viability compared to the non-exposed samples, but all doses had similar viability results. The field biofilms were highly diverse, containing not only benthic diatoms but also planktonic species which may have led to inconsistencies. Although they are different from each other, these results provide beneficial data. Cultured biofilms provide insight into how diatom cells react to varying doses of UVC radiation, whereas the real-world heterogeneity of field biofilms is useful for determining the dosage needed to effectively prevent a biofilm. Both concepts are important when developing UVC radiation management plans that target established biofilms.

Sustainable Photocatalytic Desizing Process for the Starch-Based Size.

Textile wet processing highly impacts the environment due to its massive water and energy consumption. High consumption of water also results in the generation of a considerable volume of effluents. In this regard, an ultraviolet C (UVC)-assisted desizing method of starch-sized cotton fabric has been developed to lower the utility consumption in textile pretreatment. A UVC cabinet is designed to control exposing temperature and energy of exposure on the starch-sized cotton fabric. The UVC exposure time is optimized concerning the desizing efficiency. The UVC-exposed-sized fabric is washed with different washing times and washing temperatures to optimize the process. The alkali consumption in washing is reduced by 75% and desizing efficiency is improved to 95%. The application of oxidizing agents like NaNO2, K2S2O8, and NaBO3·4H2O during sizing further reduced the washing temperature and washing time for desizing to obtain 100% desizing efficiency. The UVC-assisted desized fabric is characterized by the whiteness index, water absorbency, tensile strength, Fourier transform infrared (FTIR), and wide-angle X-ray diffraction and compared with the control. The UVC-assisted desizing process has the potential to save approximately 60% water, 90% energy, and more than 70% of the time. Life cycle analysis has also been done. The photocatalytic desizing process can reduce the impact on human health by more than 85% and save approximately 69% of mineral resources than the conventional technique. The textile industry can quickly adopt a novel approach for sustainable desizing.

266 nm ultraviolet communication under unknown interference using UVC micro-LED.

Ultraviolet C (UVC) micro light-emitting diode (LED) can achieve symbol communication rate up to 100Msps at distance 40 meters without transmitter-side lens to guarantee certain communication mobility. We consider what we believe to be a new scenario where high speed UV communciation is realized under unknown low-rate interference. The signal amplitude properties are characterized, and the interference intensity is categorized into three cases, namely weak, medium and high interference intensity. The achievable transmission rates for the three cases are derived, where the achievable transmission rate for medium interference intensity can approach those in weak interference intensity and strong interference intensity cases. We provide Gaussian approximation and related log-likelihood ratio (LLR) calculation, which are fed into the subsequent message-passing decoder. In the experiment, the data is transmitted with symbol rate 20 Msps under unknown interference with symbol rate 1 Msps, received by one photomultiplier tube (PMT). Experimental results show that the proposed interference symbol estimation approach shows negligibly higher bit error rate (BER) compared with those with perfect knowledge on the interference symbols.

Effects of curcumin supplementation on quality of porcine spermatozoa irradiated with ultraviolet-C at 228 nm during liquid preservation.

It is important to prevent microbial contamination during liquid preservation of semen in pigs. We examined the effects of curcumin supplementation on the quality of porcine spermatozoa irradiated with ultraviolet-C (UV-C) at 228 nm. UV-C is used to disinfect gases and solid surfaces. In the first experiment, porcine semen was preserved with 0, 10, 25, 50 or 100 μM curcumin under UV-C irradiation at 228 nm for 7 days at 15°C. The irradiation did not affect the motility and viability of preserved spermatozoa but decreased the percentage of plasma membrane integrity of spermatozoa. Curcumin supplementation at 25 μM significantly improved the plasma membrane and acrosome integrity of irradiated spermatozoa compared with spermatozoa preserved without curcumin (p < .05). In the second experiment, semen was preserved with or without 25 μM curcumin with UV-C irradiation at 228 or 260 nm for 3 days at 15°C. Curcumin supplementation increased the percentages of total motility, sperm viability and plasma membrane integrity of preserved spermatozoa at both irradiation wavelengths (p < .05). All quality parameters of 260 nm irradiated spermatozoa decreased compared to those of the other groups, irrespective of curcumin supplementation. The collective findings indicate that porcine spermatozoa can retain their viability even after continuous long-duration irradiation with 228 nm UV-C. Curcumin supplementation improves the quality of UV-C irradiated spermatozoa during semen preservation.

Vertical asymmetric metal-semiconductor-metal photodiode based on β-Ga2O3 thin films fabricated via solution process for arc discharge detection

Arc discharge detection is a preeminent strategy for diagnosing aging of high-power electric equipment. Therefore, the timely detection of arc discharge can prevent immense disasters, such as massive fire accidents. Ultraviolet C (UVC) photodetectors (PD) are effective devices for optical arc discharge detection because of their solar blindness, which enables noise-free and highly selective arc discharge detection. In this study, we developed a solution-processed β-Ga2O3-based vertical asymmetric metal-semiconductor-metal (MSM) UVC PD as a high-performance and inexpensive UVC detector. The high bandgap of photoactive β-Ga2O3 (4.7–5.1 eV) enables selective UVC detection. The Schottky barrier heights at two different metal-semiconductor junctions (PEDOT:PSS/β-Ga2O3 and ITO/β-Ga2O3) were systematically modulated by varying the β-Ga2O3 film annealing temperature and thickness, which enabled fast photoresponse and self-powered operation, as demonstrated by various optical and electrical analyses. The optimized device exhibited a fast photoresponse (rise/fall time of 67/53 ms) and high responsivity (41 mA W−1) and detectivity (1.5×1011 Jones) in self-powered mode. The instantaneous arc discharge was successfully detected using the β-Ga2O3 based vertical MSM PD, demonstrating its feasibility for arc discharge detection. Thus, this study provides new insights into inexpensive self-powered PDs that can be implemented for the facile and prompt monitoring of aging electric equipment and prevention of potential fire accidents.

Evaluation of Alternative-to-Gas Chlorination Disinfection Technologies in the Treatment of Maltese Potable Water

For years, gas chlorination has been the adopted disinfection technology in the treatment of Maltese potable water. Despite its strong bacterial inactivation potential, traditional chlorination generates high free chlorine residual and disinfection by-products that compromise the sensory attributes of drinking water and deter the population from consuming it. We have identified plausible alternative-to-gas-chlorination technologies for its treatment, with the aim of (a) reducing the disinfectant and/or chlorination dose used for microbial inactivation, and (b) attenuating the negative impact of putative disinfection by-products on the water’s organolepsis, while safeguarding its safe-for-consumption characteristics. We have subjected ultraviolet C (UVC) irradiation, hydrodynamic cavitation (HC), ClO2 generation, and electrochlorination (NaClO) to bacteriological and physicochemical bench-scale studies to assess their bacterial inactivation efficacy and by-product generation propensity, respectively. All the tested technologies except HC achieved a minimum of 3 Log10 microbial inactivation, with NaClO and ClO2 appearing more effective over neutral and alkaline pH conditions, respectively. In addition, we have identified synergistic effects of cavitation on UVC for Enterococcus faecalis inactivation, stemming from enhancement in oxidative stress. Moderate reductions in the total dissolved solid content and Ca2+ hardness of the tested water also emerged following prolonged cavitation. For feasibility studies, the performance of the technologies was further evaluated on the following areas: (a) implementation, (b) practicality, (c) adaptability, (d) integration, (e) environment and sustainability, and (f) cost and effect. Electrochemical generation of NaClO emerged as the most promising technology for further on-site work, followed by ClO2 and UVC.

Reducing Powdery Mildew in High-tunnel Tomato Production in Oregon with Ultra Violet-C Lighting

Widespread outbreaks of tomato powdery mildew (Leveillula taurica and Oidium neolycopersici) are problematic in fresh market tomato (Solanum lycopersicum) crops in western Oregon, USA. In western Oregon, fresh market tomatoes are frequently grown in greenhouses or high tunnels where conditions can promote diseases such as powdery mildew. Heightened concerns about worker safety limit the pesticides available for use in enclosed systems. We studied the efficacy of ultraviolet-C (UV-C) light applications under high-tunnel conditions compared with a standard fungicide program. Plants treated with UV-C had zero incidence of powdery mildew on all sample dates in the first trial. In trial 2, disease incidence was lower on UV-C treated plants than both grower standard and nontreated control early in the study while disease severity remained lower in UV-C than nontreated control and similar to grower standard treatment. Additional research is needed to optimize UV-C treatment intervals to minimize negative effects on plant growth and maximize powdery mildew control.

Investigation of Ultraviolet-C light-emitting diode for airborne disinfection in air duct

Given the current coronavirus (COVID-19) situation around the world, we may have to face a long-term battle with coronavirus. It is necessary to prepare and stay resilient with some other techniques to improve air quality in buildings, especially in clinics and hospitals. In this paper, we have developed Ultraviolet-C (UVC) light-emitting diode (LED) modules which can be implemented in air ducts in heating, ventilation, and air conditioning system for airborne disinfection. An LED module is designed with LED panels as the basic unit so that it is easy to scale up to accommodate for air ducts with different sizes. Both experiments and simulations are carried out to study its disinfection performance. The results show that more than 76% and 85% of the pathogen can be inactivated within 60 and 90 min, respectively, in a meeting room with a volume of 107 m3 by using one LED module. Simulations for two LED modules show that the disinfection efficacy is more than two times compared to that of one LED module. In addition to the pathogen used in the experiments, the disinfection performance of the LED module for inactivation of SARS-CoV-2 virus based on the literature is investigated numerically. It shows that more than 99.70% of pathogens receive UV dose larger than 4.47 J/m2, leading to an almost 89.10% disinfection rate for SARS-CoV-2 virus within one hour using the two LED modules in the same meeting room.

Pulsed magnetic field increases the effect of ultraviolet C radiation and thermal shock in aged yeasts

The study of the effects of the magnetic field (MF) on living matter continues to be a dilemma. Until now, the interaction mechanisms of MF with living matter that explain the observed phenomena are unknown. Despite the existing literature and the multiple effects described to date, there are few published articles that study the combined effect of MF with other physical agents during the cellular aging process. In this sense, the aim of this work is to study whether low frequency and intensity pulsed and sinusoidal MF exposure produce alterations in the cell killing effect of ultraviolet C (UVC) radiation and thermal shock during the chronological aging of S. cerevisiae. Yeast cells were exposed to 2.45 mT (50 Hz) sinusoidal MF and 1.5 mT (25 Hz) pulsed MF, during 40 days of aging, in combination with UVC radiation (50 J/m2) and/or thermal shock (52°C). Cell survival was evaluated by clonogenic assay. The exposure of yeast to pulsed MF produces an acceleration of aging, which is not observed in cells exposed to sinusoidal MF. The pulsed MF modifies the cellular response to damaging agents only in aged S. cerevisiae cells. In this sense, the pulsed MF applied increases the damage induced by UVC radiation and by thermal shock. In contrast, the sinusoidal MF used has no effect.

Conceptual Design of a UVC-LED Air Purifier to Reduce Airborne Pathogen Transmission—A Feasibility Study

Existing indoor closed ultraviolet-C (UVC) air purifiers (UVC in a box) have faced technological challenges during the COVID-19 breakout, owing to demands of low energy consumption, high flow rates, and high kill rates at the same time. A new conceptual design of a novel UVC-LED (light-emitting diode) air purifier for a low-cost solution to mitigate airborne diseases is proposed. The concept focuses on performance and robustness. It contains a dust-filter assembly, an innovative UVC chamber, and a fan. The low-cost dust filter aims to suppress dust accumulation in the UVC chamber to ensure durability and is conceptually shown to be easily replaced while mitigating any possible contamination. The chamber includes novel turbulence-generating grids and a novel LED arrangement. The turbulent generator promotes air mixing, while the LEDs inactivate the pathogens at a high flow rate and sufficient kill rate. The conceptual design is portable and can fit into ventilation ducts. Computational fluid dynamics and UVC ray methods were used for analysis. The design produces a kill rate above 97% for COVID and tuberculosis and above 92% for influenza A at a flow rate of 100 L/s and power consumption of less than 300 W. An analysis of the dust-filter performance yields the irradiation and flow fields.

Oxygen Effect on the Ultraviolet-C Photochemistry of Lactic Acid.

Lactic acid, a small α-hydroxyacid, is ubiquitous in both indoor and outdoor environments. Recently, the photochemistry of lactic acid has garnered interest among the abiotic organic chemistry community as it would have been present in abiotic settings and photoactive with the high-energy solar radiation that would have been available in the low oxygen early Earth environment. Additionally, we propose that the photochemistry of lactic acid is relevant to modern Earth during indoor ultraviolet-C (UVC) sterilization procedures as lactic acid is emitted by humans and is thus prevalent in indoor environments where UVC sterilization is increasingly being used. Here, we study the oxygen effect on the gas phase photolysis of lactic acid using Fourier-transform infrared (FTIR) spectroscopy and isotopically labeled oxygen (18O2). We find that the major products of gas phase lactic acid photolysis are CO2, CO, acetaldehyde, and acetic acid. Furthermore, these products are the same with or without added oxygen, but the partial pressures of produced CO2, CO, and acetaldehyde increase with the amount of added oxygen. Notably, the added oxygen is primarily incorporated into produced CO2 and CO, while little or none is incorporated into acetaldehyde. We combine the results presented here with those in the literature to propose a mechanism for the gas phase photolysis of lactic acid and the role of oxygen in this mechanism. Finally, we compare the output of a krypton-chloride excimer lamp (λ = 222 nm), one of the lamps proposed for UVC sterilization procedures, to the absorption of lactic acid. We show that lactic acid would be photoactive during UVC sterilization procedures, and we use the gas phase results presented here and aqueous lactic acid photolysis results previously published to assess potential byproducts from lactic acid reactions during UVC sterilization procedures.