Search Results (39)

In South Korea, issues have been raised regarding exposure to humidifier disinfectant products containing certain chemicals postulated to induce lung diseases in consumers. Several rodent studies utilizing whole-body inhalation, which comprises freely moving animals breathing through the nares, and intranasal instillation involving restraint, were conducted by various Korean Governmental Agencies on these products to investigate whether there is a causal relationship between these products and the development of lung diseases. In particular, the humidifier disinfectant product Kathon, containing chloromethylisothiazolinone and methylisothiazolinone (CMIT and MIT), when directly introduced into inhalation chambers at varying concentrations for up to 13 weeks, produced no significant histopathological alterations and no marked changes in pulmonary function parameters. Further, there was no evidence of cytotoxicity; total and differential cell counts did not differ from control. In addition, the levels of cytokine markers of inflammation were not markedly altered. In contrast to published papers utilizing intratracheal and intranasal instillation, where the animal is anesthetized and chemical bypasses the defense mechanisms in the respiratory tract, then reaches the pulmonary region, ignoring recommended dose levels was found to initiate fibrotic responses in mice and rats. However, the usefulness of experimental results to extrapolate to humans obtained following intratracheal and intranasal instillation studies is of limited value because the data generated did not use a realistic design and appropriate dosimetry. Therefore, these findings have significant drawbacks in their use to characterize an inhalation risk for pulmonary fibrosis in humans and cannot be used for the extrapolation of such risk to humans. It is thus evident that the inhalation data generated by the Korean Regulatory Agencies are more realistic and show that exposure to CMIT and MIT does not initiate pulmonary fibrosis. Although inhalation studies still do not fully replicate real-world human exposure scenarios and have limitations for direct extrapolation to humans, they are nevertheless more appropriate than intratracheal or intranasal instillation models. Full article

Common designs of workwear drying units require not only energy efficiency but also effective disinfection. One possibility of sanitising clothes during drying is to use the ozone generated inside the drying chamber. This process requires precise management of airflow and a uniform distribution of ozone in the chamber. Therefore, optimising the shape of the drying chamber must include not only the correct flow of drying air but also the correct distribution of ozone. This paper addresses the difficult problem of modelling the flow of sanitising ozone in an innovative drying chamber. The innovative shape of the chamber is shown in this article. Due to the low percentage of ozone in the air (up to 10 ppm), CFD simulation models of the usual mixture type are too inaccurate; therefore, special models have to be used. Therefore, this paper presents an experimentally verified methodology to simulate ozone flow in an innovative drying and sanitising cabinet using two methods: Discrete Phase Model (DPM) and Species Transport (ST). The DPM method uses a Euler–Lagrange approach to qualitatively assess the spread of ozone particles, treated with a description of the movement of the particles and not as a continuous gaseous substance. On the other hand, this already allows the verification of ozone concentrations, with an appropriate conversion of the measured quantities. The ANSYS/FLUENT 2023R1 program was used for the simulations after careful selection of the mesh, closing models, boundary conditions, etc. Simulations made it possible to analyse the distribution of ozone in the workspace and assess the effectiveness of the sanitisation process. The results of the simulations were verified on the basis of empirical tests, which showed the correctness of the model and the correct distribution of the sanitising ozone in the entire volume of the drying chamber in the innovative drying–sanitising chamber. The complete simulation of the air and ozone distribution using the presented models allowed for the optimisation of the opening and shapes, which contributed to improving the energy efficiency of the unit and increasing the efficiency of the sanitisation processes, making the described methodology very effective for optimising the chambers of various types of dryers. Full article

Ultraviolet shortwave (UV-C) is a technology for postharvest fruit disinfection. This study aimed to use computational fluid dynamics (CFD) based on the discrete ordinate (DO) radiation model to analyze the distribution of UV-C intensity on whole and minimally processed mangoes within a disinfection chamber and to predict treatments against foodborne pathogens. The mango spears were oriented both parallel and perpendicular to the lamp and positioned at varying distances from the radiation source (50, 75, and 100 mm for spears and 100 mm for whole fruit). CFD simulations integrated with in vitro kinetic parameters enabled predictions of the time and doses needed to inactivate one to three logarithmic units of pathogens on the fruit surface. The highest average radiation intensity values were recorded for the whole mango oriented parallel to the lamp at 100 mm and the spears oriented normally to the lamp at 50 mm. The estimated times to achieve inactivation of one to three logarithmic units of microorganisms ranged from approximately 15 to 6540 s, while the doses necessary for this inactivation were, on average, 1.854, 5.291, and 10.656 kJ/m², respectively. CFD simulations are valuable for optimizing UV-C treatments in large-scale designing from both microbicide and sustainable perspectives. Full article

Despite best efforts in air purification, airborne infectious diseases will continue to spread due to the continuous emission of bioaerosols by the host/infected person. Hence, a shift in focus from air purification to bioaerosol inactivation is urgently needed. To explore the potential of the cold plasma technology for preventing rapid spread of airborne infectious diseases, we studied a cold plasma ionizer (CPI) device and an electrostatic precipitator (ESP)-coupled CPI (CPI-ESP) device for the inactivation and cleaning of surface-spread microorganisms and bioaerosols, using porcine respiratory coronavirus (PRCV), Escherichia coli (E. coli), and aerosolized E. coli as representatives. We firstly demonstrated that CPI coupled with ESP is an effective technology for inactivating virus and bacteria spread on surfaces in an in-house test chamber. We then demonstrated the efficacy of CPI-coupled ESP for the inactivation of aerosolized E. coli in the same chamber. Furthermore, we have demonstrated the efficiency of a CPI-ESP coupled device for the inactivation of naturally occurring airborne microbials in a few indoor settings (i.e., a living room, a discussion room, a schoolroom, and an office) to determine the treatment duration- and human activity-dependent efficacy. To understand the disinfection mechanism, we conducted a fluorescence microscopy study to reveal different degrees of E. coli bacteria cell membrane damage under CPI treatment. Full article

This publication presents the effect of hypochlorous acid dry mist as a disinfectant on selected bacteria, viruses, spores, and fungi as well as on portable Microlife OXY 300 finger pulse oximeters and electronic systems of Raspberry Pi Zero microcomputers. The impact of hypochlorous acid on microbiological agents was assessed at concentrations of 300, 500, and 2000 ppm of HClO according to PN-EN 17272 (Variant I). Studies of the impact of hypochlorous acid fog on electronic components were carried out in an aerosol chamber at concentrations of 500 ppm and 2000 ppm according to two models consisting of 30 (Variant II) and 90 fogging cycles (Variant III). Each cycle included the process of generating a dry mist of hypochlorous acid (25 mL/m³), decontamination of the test elements, as well as cleaning the chamber of the disinfectant agent. The exposure of the materials examined on hypochlorous acid dry mist in all variants resulted in a decrease in the number of viruses, bacteria, spores, and fungi tested. In addition, the research showed that in the variants of hypochlorous acid fogging cycles analyzed, no changes in performance parameters and no penetration of dry fog of hypochlorous acid into the interior of the tested medical devices and electronic systems were observed. Full article

The microbiome of the ocular surface has been characterised, but only limited information is available on a possible silent intraocular microbial colonisation in normal eyes. Therefore, we performed next-generation sequencing (NGS) of 16S rDNA genes in the aqueous humour. The aqueous humour was sampled from three patients during cataract surgery. Air swabs, conjunctival swabs from patients as well as from healthy donors served as controls. Following DNA extraction, the V3 and V4 hypervariable regions of the 16S rDNA gene were amplified and sequenced followed by denoising. The resulting Amplicon Sequence Variants were matched to a subset of the Ribosomal Database Project 16S database. The deduced bacterial community was then statistically analysed. The DNA content in all samples was low (0–1.49 ng/µL) but sufficient for analysis. The main phyla in the samples were Acinetobacteria (48%), Proteobacteria (26%), Firmicutes (14%), Acidobacteria (8%), and Bacteroidetes (2%). Patients’ conjunctival control samples and anterior chamber fluid showed similar patterns of bacterial species containing many waterborne species. Non-disinfected samples showed a different bacterial spectrum than the air swab samples. The data confirm the existence of an ocular surface microbiome. Meanwhile, a distinct intraocular microbiome was not discernible from the background, suggesting the absence of an intraocular microbiome in normal eyes. Full article

Tropical and subtropical crops are being increasingly cultivated in South Korea, leading to an increase in damage by exotic insect pests. Consequently, ethyl formate (EF) is currently being considered for quarantine and pre-shipment fumigation. In this study, we evaluated the effectiveness of EF fumigation for controlling Aphis spiraecola Patch and Aphis gossypii Glover, two representative quarantine pests on passion fruit (“Pink Bourbon”) during greenhouse cultivation and post-harvest storage. The efficacy of EF against both aphids in terms of the lethal concentration causing 50% mortality (LCt_50%) and LCt_99% was 1.36–2.61 g h/m³ and 3.73–7.55 g h/m³ under greenhouse conditions (23 °C), and 1.37–2.02 g h/m³ and 3.80–14.59 g h/m³ post-harvest (5 °C), respectively. EF at 4 g/m³ for 4 h resulted in 100% mortality of A. spiraecola, which was more resistant to EF, without causing phytotoxic damage to the trees in a 340 m³ greenhouse. Post-harvest fruit fumigation at 10 g/m³ for 4 h in a mid-size (0.8 m³) fumigation chamber resulted in complete disinfection. Moreover, the EF level decreased below the EF threshold within 10 min after natural ventilation in the greenhouse. Therefore, our results suggest EF fumigation as an effective method for controlling A. spiraecola and A. gossypii. Full article

Apple production holds a prominent position in Morocco’s Rosaceae family. However, annual production can fluctuate due to substantial losses caused by fungal diseases affecting stored apples. Our findings emphasize that the pre-storage treatment of apples, disinfection of storage facilities, box type, and fruit sorting are pivotal factors affecting apple losses during storage. Additionally, the adopted preservation technique was significantly correlated with the percentage of damage caused by fungal infections. Blue mold accounts for nearly three-quarters of the diseases detected, followed by gray rot with a relatively significant incidence. This study has revealed several fungal diseases affecting stored apples caused by pathogens such as Penicillium expansum, Botrytis cinerea, Alternaria alternata, Trichothecium roseum, Fusarium avenaceum, Cadophora malorum, and Neofabraea vagabunda. Notably, these last two fungal species have been reported for the first time in Morocco as pathogens of stored apples. These data affirm that the high losses of apples in Morocco, attributed primarily to P. expansum and B. cinerea, pose a significant threat in terms of reduced production and diminished fruit quality. Hence, adopting controlled atmosphere storage chambers and implementing good practices before apple storage is crucial. Full article

Pineapple mealybug, Dysmicoccus brevipes (Hemiptera: Pseudococcidae), is a significant pest in pineapple production and a key trade barrier. We explored the potential use of ethyl formate (EF) as a methyl bromide alternative for the postharvest fumigation of D. brevipes in imported pineapples. When treated at 8 °C for 4 h, EF fumigation was effective against D. brevipes with LCt_99, the lethal concentration × time product of EF necessary to achieve 99% mortality of D. brevipes nymphs and adults at 64.2 and 134.8 g h/m³, respectively. Sorption trials conducted with 70 g/m³ EF for 4 h at 8 °C using 7.5, 15 and 30% pineapple loading ratios (w/v) indicated that loading ratio lower than 30% is necessary to achieve the LCt₉₉ values required to control D. brevipes. In a scaled up trial using 1 m³ chamber, EF fumigation with 70 g/m³ for 4 h at 8 °C with 20% pineapple loading ratio (w/v) resulted in a complete control of D. brevipes treated. There were no significant differences in hue values, sugar contents, firmness, and weight loss between EF-treated and untreated pineapples. Our results suggest that EF is a promising alternative to methyl bromide fumigation for the postharvest phytosanitary disinfection of D. brevipes in pineapples. Full article

Avian influenza virus (AIV) can have a serious impact on both human and animal health. In this study, we used an environmentally controlled chamber and a hemagglutination assay (HA) to evaluate the ability of membrane-less electrolyzed water (MLEW) spraying to inactivate H6N1 AIV aerosol. MLEW was generated by electrolyzing sodium chloride solution, and then sprayed into the chamber at free available chlorine (FAC) concentrations of 50, 100 and 200 mg/L by means of high-pressure air pumping to inactivate airborne H6N1 AIV aerosols individually. The results showed that MLEW spraying effectively neutralized H6N1 AIV aerosol. In addition, the virucidal ability of MLEW increased as the FAC concentration increased. Five minutes after MLEW spraying at an FAC concentration of 200 mg/L, the H6N1 viral HA titer decreased from 2⁴ to 2⁰. Our work provides important new evidence of the value of spraying with MLEW disinfectant to protect against AIV, which may be further applied for indoor decontamination purposes to promote animal and human health. Full article

Two prevalent bacterial diseases in catfish aquaculture are enteric septicemia of catfish and columnaris disease caused by Edwardsiella ictaluri and Flavobacterium covae, respectively. Chronic and recurring outbreaks of these bacterial pathogens result in significant economic losses for producers annually. Determining if these pathogens can persist within sediments of commercial ponds is paramount. Experimental persistence trials (PT) were conducted to evaluate the persistence of E. ictaluri and F. covae in pond sediments. Twelve test chambers containing 120 g of sterilized sediment from four commercial catfish ponds were inoculated with either E. ictaluri (S97-773) or F. covae (ALG-00-530) and filled with 8 L of disinfected water. At 1, 2, 4-, 6-, 8-, and 15-days post-inoculation, 1 g of sediment was removed, and colony-forming units (CFU) were enumerated on selective media using 6 × 6 drop plate methods. E. ictaluri population peaked on Day 3 at 6.4 ± 0.5 log₁₀ CFU g⁻¹. Correlation analysis revealed no correlation between the sediment physicochemical parameters and E. ictaluri log₁₀ CFU g⁻¹. However, no viable F. covae colonies were recovered after two PT attempts. Future studies to improve understanding of E. ictaluri pathogenesis and persistence, and potential F. covae persistence in pond bottom sediments are needed. Full article

In the process of sewage treatment, the characteristics of dissolved organic matter (DOM) are always changed during chemical and biological processes, affecting the generation of disinfection by-products (DBPs) compositions at the following disinfection stage. The present study systematically investigated the effect of DOM characterization on C- and N-DBPs formation at AAO-MBR reactor when treating wastewater. The results showed that the AAO-MBR treatment process could efficiently eliminate dissolved organic carbon (DOC) and ammonium nitrogen (NH₄⁺-N) from wastewater with an elimination rate of 89% and 98%, respectively. Most of the precursors (i.e., 56.8% C-DBPs and 78.1% N-DBPs) were removed at the MBR unit, while AGC and AAO units promoted the formation of DBPs precursors. More specifically, soluble microbial products (SMPs) and humus acid were increased, which led to improved C- and N-DBPs via aerated grit chamber (AGC) treatment. At the AAO treatment unit, the content of low MW hydrophobic SMPs, humus acid, and polysaccharides was increased, indicating low MW and HPO fractions dominating the C- and N-DBPs. MBR treatment improved C-DBPs in high MW and HPO fractions and N-DBPs in low MW and HPO fractions, which is explained by higher MW hydrophobic SMPs and humus acids, compared to the AAO unit. The present study provided deep insight into the linkage of DOM characteristics and C- and N-DBPs formation at each treatment unit during the AAO-MBR process. Full article

There is an ever-growing need in several industries to disinfect or sanitise products (i.e., to reduce or eliminate pathogenic microorganisms from their surfaces). Gaseous ozone has been widely applied for this purpose, particularly during the era of the COVID-19 pandemic. However, the large-scale deployment of this technology usually involves a manually-operated chamber, into which articles are loaded and subsequently unloaded after treatment—a batch process. Although the development of large-scale, automated and continuous ozonation equipment has hardly been reported in the literature, this has tremendous potential for industries seeking to decontaminate certain articles/products in a rapid and effective manner. In this paper, an overview of the design and implementation considerations for such an undertaking is evaluated. By presenting a case study for a developed automated system for clothing and personal protective equipment (PPE) disinfection, we provide key data regarding the automation procedure/design’s considerations, risks, material compatibility, safety, sustainability and process economics. Our analysis shows that the transfer time for garments between successive chambers and the agility of the sliding doors are crucial to achieving the desired throughput. The automated system is capable of effectively treating (20 ppm ozone for 4 min) 20,000 garments within an 8-h shift, based on a transfer time of 2 min and a sliding door speed of 0.4 m/s. The flexibility of the system allows for variation in the concentration or exposure time, depending on the contamination level and the consequent decontamination efficiency desired. This flexibility significantly limits the degradation of the material during treatment. A return on investment of 47% is estimated for this novel system. Full article

Biocides are widely used in everyday life, and accordingly, human exposure to them is inevitable. Especially, the inhalational exposure of humans to biocides and resultant respiratory toxicity are gaining public interest due to the recent catastrophe associated with humidifier disinfectants. Aerosolized chemicals are subject to gravitational deposition and chemical degradation. Therefore, the characterization of the disposition of aerosols is essential to estimate the inhalational exposure to biocides. Here, we compared the disposition of aerosols of one of the commonly used biocide classes, isothiazolinone-based biocides, BIT, MIT, and OIT. An acrylic chamber (40 cm × 40 cm × 50 cm) was created to simulate the indoor environment, and a vacuum pump was used to create airflow (1 LPM). Biocides were sprayed from a vertical nebulizer placed on the ceiling of the chamber, and the distribution of particle sizes and volume was measured using the Optical Particle Sizer (OPS) 3330 device. During and after the aerosol spraying, airborne biocides and those deposited on the surface of the chamber were sampled to measure the deposition using LC-MS/MS. As a result, the broad particle size distribution was observed ranging from 0.3 to 8 μm during the nebulization. The inhalable particle faction (>2 μm) of the isothiazolinones was 32–67.9% in number but 1.2 to 6.4% in volume. Most of the aerosolized biocides were deposited on the chamber’s surface while only a minimal portion was airborne (<1%) after the nebulization. More importantly, significant amounts of MIT and OIT were degraded during aerosolization, resulting in poor total recovery compared to BIT (31%, 71% vs. 97% BIT). This result suggests that some isothiazolinones may become unstable during nebulization, affecting their disposition and human exposure significantly. Full article

Vehicle Heating, ventilation, and air conditioning (HVAC) systems can accumulate and recirculate highly infectious respiratory diseases via aerosols. Integrating Ultraviolet Subtype C (UVC) light-emitting diodes (LEDs) to complement automobile HVAC systems can protect occupants from developing allergies, experiencing inflammatory problems, or acquiring respiratory infectious diseases by inactivating pathogenic organisms. UVC can add little to no static pressure with minimal space, unlike mercury lamps which are larger and heavier. Additionally, UVC LEDs are effective at low voltage and have no mercury or glass. While previous experiments have shown UVC LED technology can reduce bacteriophage Phi6 concentrations by 1 log in 5 min (selected as the average time to clean the cabin air), those studies had not positioned LED within the HVAC itself or studied the susceptibility of the surrogate at the specific wavelength. This study aimed to assess the disinfection performance of UVC LEDs in automotive HVAC systems and determine the dose–response curve for bacteriophage Phi6, a SARS-CoV-2 surrogate. To achieve this, UVC LEDs were installed in a car HVAC system. To determine inactivation efficacy, a model chamber of 3.5 m³, replicating the typical volume of a car, containing the modified automobile HVAC system was filled with bacteriophage Phi6, and the HVAC was turned on with and without the UVC LEDs being turned on. The results revealed that HVAC complemented with UVC reduced bacteriophage Phi6 levels significantly more than the HVAC alone and reduced the viral concentration in the cabin by more than 90% viral reduction in less than 5 min. The performance after 5 min is expected to be significantly better against SARS-CoV-2 because of its higher sensitivity to UVC, especially at lower wavelengths (below 270 nm). HVAC alone could not achieve a 90% viral reduction of bacteriophage Phi6 in 15 min. Applying UVC LEDs inside an HVAC system is an effective means of quickly reducing the number of aerosolized viral particles in the chamber, by inactivating microorganisms leading to improved cabin air quality. Full article