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Inactivation of Airborne Pathogenic Microorganisms by Plasma-activated Nebulized Mist
Abstract
The airborne microorganisms in the aerosols are one main transmission way of pathogenic microorganisms and therefore inactivation of microorganisms in aerosols could effectively prevent the transmission of pathogenic microorganisms to control epidemics. The mist nebulized by plasma-activated air could effectively inactivate bacteria and could be developed for the sterilization of microorganisms in aerosols. In this study, the plasma-activated nebulized mist (PANM) was applied for the inactivation of microorganisms in aerosols and efficiently inactivated the bacteria, yeast, and viruses in aerosols after 2-min treatment. The PANM treatment caused morphologic changes and damage to the bacteria cells in aerosols. The PANM could also inactivate the microorganisms attached to the surface of the treatment chamber and the bacteria attached to the skin of mice within 6-min treatment. The biosafety assays demonstrated that the PANM treatment exhibited no effects on the behavior, hematological and serum biochemical parameters of blood, and organs from the mice. This study would supply an efficient, broad-spectrum, and safe aerosol sterilization strategy based on plasma technology to prevent the transmission of airborne microorganisms.
... Studying pathogens and corrosive bacteria is crucial for human health and the economy. [1][2][3] These microorganisms pose threats in healthcare, food safety, environmental protection, and industry, causing diseases, mortalities, infrastructure damages, and economic losses. [4][5][6] Some bacteria are commonly found in the environment and exhibit both pathogenicity and corrosive properties, 7,8 such as Pseudomonas aeruginosa (P. ...
Pathogenic and corrosive bacteria pose a significant risk to human health or economic well‐being. The specific, sensitive, and on‐site detection of these bacteria is thus of paramount significance but remains challenging. Taking inspiration from immunoassays with primary and secondary antibodies, we describe here a rational design of microbial sensor (MS) under a dual‐specificity recognition strategy using Pseudomonas aeruginosa ( P. aeruginosa ) as the detection model. In the MS, engineered aptamers are served as the primary recognition element, while polydopamine‐ N ‐acetyl‐D‐galactosamine (PDA‐Gal NAc) nanoparticles are employed as the secondary recognition element, which will also generate and amplify changes in the output voltage signal. To achieve self‐powering capability, the MS is constructed based on a triboelectric nanogenerator (TENG) with the specific aptamers immobilized on the TENG electrode surface. The as‐prepared MS‐TENG system exhibits good stability in output performance under external forces, and high specificity toward P. aeruginosa , with no cross‐reactivity observed. A linear relationship ( R ² = 0.995) between the output voltage and P. aeruginosa concentration is established, with a limit of detection estimated at around 8.7 × 10 ³ CFU mL ⁻¹ . The utilization of PDA‐Gal NAc nanoparticles is found to play an important role in enhancing the specific and reliability of detection, and the underlying mechanisms are further clarified by computational simulations. In addition, the MS‐TENG integrates a wireless communication module, enabling real‐time monitoring of bacterial concentration on mobile devices. This work introduces a pioneering approach to designing self‐powered smart microbial sensors with high specificity, using a double recognition strategy applicable to various bacteria beyond P. aeruginosa . image
Plasma‐based technology has been widely applied in the biomedicine, agriculture, and environmental fields. In this study, a new application mode, namely plasma‐activated nebulized mist (PANM) was proposed. The saline was nebulized by the plasma‐activated air to form a mist, and the inactivation effects on Pseudomonas aeruginosa were analyzed based on the simulated respiratory tract. The PANM through the simulated trachea with different lengths or diameters, and the branched once or twice simulated respiratory tract exhibited effective inactivation effects. The PANM through the combined simulated trachea and pig trachea could also inactivate the bacteria on the inner wall of the pig trachea. This study supplied a potent alternative to antibiotics for the treatment of respiratory tract infections. A new application mode namely plasma‐activated nebulized mist (PANM) was proposed in this study. The saline was nebulized by the plasma‐activated air to form a mist, and the inactivation effects on Pseudomonas aeruginosa were analyzed based on the simulated respiratory tract. The PANM through the simulated trachea with different lengths or diameters, the branched once or twice simulated respiratory tract, and the combined simulated trachea and pig trachea all exhibited effective inactivation effects. This study supplied a potent alternative to antibiotics for the treatment of respiratory tract infections.
N2O5, a reactive species produced by air discharge plasma, has recently attracted much attention. Due to its high reactivity and solubility, N2O5 is a key molecule in nitrogen fixation processes and exhibits promising prospects in plasma biomedicine. However, thus far, it is not well known how to produce N2O5 efficiently and then maintain its concentration under the action of fast removal reactions. In view of this, N2O5¬ production by dielectric barrier discharge (DBD) alone and by the combination of DBD and gliding arc discharge is compared in this paper. It is found that the combination method can yield over three times the concentration of N2O5 compared to the single DBD method with the optimum discharge power. Moreover, the concentration of N2O5 in the effluent gas can be maintained once O3 also exists because O3 can continually produce N2O5 to compensate for its reduction. Finally, the sterilization effects of both the plasma effluent gas and plasma-activated water (PAW) have trends similar to the trend of the gaseous N2O5 concentration, implying that N2O5 plays an important role in sterilization. This paper enhances the understanding of N2O5 chemistry in air discharge plasma and provides an effective way to produce and maintain N2O5 for subsequent applications.
Introduction
Airborne transmission is the most crucial mode of COVID‐19 transmission. Therefore, disinfecting the severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) aerosols float can have important implications in limiting COVID‐19 transmission. Herein, we aimed to review the studies that utilized various disinfectants to decontaminate and inactivate the SARS‐CoV‐2 aerosols.
Methods
This study was a review that studied related articles published between December 1, 2019 and August 23, 2022. We searched the online databases of PubMed, Scopus, Web of Science, Cochrane, on August 23, 2021. The studies were downloaded into the EndNote software, duplicates were removed, and then the studies were screened based on the inclusion/exclusion criteria. The screening process involved two steps; first, the studies were screened based on their title and abstract and then their full texts. The included studies were used for the qualitative analysis.
Results
From 664 retrieved records, only 31 met the inclusion criteria and were included in the final qualitative analysis. Various materials like Ozone, H2O2, alcohol, and TiO2 and methods like heating and using Ultraviolet were described in these studies to disinfect places contaminated by COVID‐19. It appeared that the efficacy of these disinfectants varies considerably depending on the situation, time, and ultimately their mode of application.
Conclusion
Following reliable protocols in combination with the proper selection of disinfectant agents for each purpose would serve to achieve desired elimination of the SARS‐CoV‐2 transmission.
Unlabelled:
Policies and measures to control pandemics are often failing. While biological factors controlling transmission are usually well explored, little is known about the environmental drivers of transmission and infection. For instance, respiratory droplets and aerosol particles are crucial vectors for the airborne transmission of the severe acute respiratory syndrome coronavirus 2, the causation agent of the coronavirus 2019 pandemic (COVID-19). Once expectorated, respiratory droplets interact with atmospheric particulates that influence the viability and transmission of the novel coronavirus, yet there is little knowledge on this process or its consequences on virus transmission and infection. Here we review the effects of atmospheric particulate properties, vortex zones, and air pollution on virus survivability and transmission. We found that particle size, chemical constituents, electrostatic charges, and the moisture content of airborne particles can have notable effects on virus transmission, with higher survival generally associated with larger particles, yet some viruses are better preserved on small particles. Some chemical constituents and surface-adsorbed chemical species may damage peptide bonds in viral proteins and impair virus stability. Electrostatic charges and water content of atmospheric particulates may affect the adherence of virion particles and possibly their viability. In addition, vortex zones and human thermal plumes are major environmental factors altering the aerodynamics of buoyant particles in air, which can strongly influence the transport of airborne particles and the transmission of associated viruses. Insights into these factors may provide explanations for the widely observed positive correlations between COVID-19 infection and mortality with air pollution, of which particulate matter is a common constituent that may have a central role in the airborne transmission of the novel coronavirus.
Supplementary information:
The online version contains supplementary material available at 10.1007/s10311-022-01557-z.
The global pandemic caused by SARS-CoV-2 has lasted two and a half years and the infections caused by the viral contamination are still occurring. Developing efficient disinfection technology is crucial for the current epidemic or infectious diseases caused by other pathogenic microorganisms. Gas plasma can efficiently inactivate different microorganisms, therefore, in this study, a combination of water spray and plasma-activated air was established for the disinfection of pathogenic microorganisms. The combined treatment efficiently inactivated the Omicron-pseudovirus through caused the nitration modification of the spike proteins and also the pathogenic bacteria. The combined treatment was improved with a funnel-shaped nozzle to form a temporary relatively sealed environment for the treatment of the contaminated area. The improved device could efficiently inactivate the Omicron-pseudovirus and bacteria on the surface of different materials including quartz, metal, leather, plastic, and cardboard and the particle size of the water spray did not affect the inactivation effects. This study supplied a disinfection strategy based on plasma-activated air for the inactivation of contaminated pathogenic microorganisms.
[This corrects the article DOI: 10.1098/rsfs.2021.0072.][This corrects the article DOI: 10.1098/rsfs.2021.0072.].
Introduction
Occupational hand dermatitis is common among healthcare workers, with increased incidence during the COVID-19 pandemic. Irritant contact dermatitis accounts for the majority of occupational hand dermatitis and is largely due to frequent contact with hand hygiene products. Long-term prognosis of occupational contact dermatitis is often very poor. This study aims to identify and implement suitable workplace interventions to aid in the recovery of occupational irritant hand dermatitis among healthcare workers during the COVID-19 pandemic.
Methods
A quality improvement (QI) project was performed in a tertiary hospital using the Plan-Do-Study-Act model. Healthcare workers seen at the Occupational Dermatology Clinic from March 2020 to May 2021 for the first time for likely occupational irritant dermatitis were targeted for the project. Four workplace interventions were implemented: (a) substitute current alcohol-based hand rub (ABHR) with a different, gentler ABHR, (b) alternate ABHR with gentle hand wash products, (c) temporary job modification with less clinical work (d) switch latex gloves to nitrile gloves. The improvement was assessed after 2 months of workplace intervention using a visual analogue scale, based on changes seen on photographs taken at the baseline and monthly review. The target improvement was set at 70% after 2 months of workplace interventions.
Results
A total of 21 participants were included in the QI project. All participants were found to have significant improvement in their hand condition. The estimated mean reduction of signs and symptoms was 80% in comparison to their baseline hand condition before intervention.
Conclusion
Workplace interventions such as substituting irritant hand hygiene products with gentler alternatives and temporary reduction in clinical duties may be useful in improving the recovery rate of irritant hand dermatitis among healthcare workers. Areas with high hand hygiene workload or high incidences of hand dermatitis may opt to implement systemic workplace changes.
Metal mesh devices (MMDs) are novel materials that enable the precise separation of particles by size. Structurally, MMDs consist of a periodic arrangement of square apertures of characteristic shapes and sizes on a thin nickel membrane. The present study describes the separation of aerosol particles using palm-top-size collection devices equipped with three types of MMDs differing in pore size. Aerosols were collected at a farm located in the suburbs of Nairobi, Kenya; aerosol particles were isolated, and pathogenic bacteria were identified in this microflora by next-generation sequencing analysis. The composition of the microflora in aerosol particles was found to depend on particle size. Gene fragments were obtained from the collected aerosols by PCR using primers specific for the genus Mycobacterium. This analysis showed that Mycobacterium obuense, a non-tuberculous species of mycobacteria that causes lung diseases, was present in these aerosols. These findings showed that application of this MMD analytical protocol to aerosol particles can facilitate the investigation of airborne pathogenic bacteria.
Air plasma is commonly used to treat water for activation or purification, and plasma-activated water (PAW) is a promising green disinfectant that has attracted great attention in recent years. However, either the O3 discharge mode or the NOx discharge mode of air plasma lacks efficiency for water activation mainly due to the low solubility of O3, NO, and NO2. The transition process between those two modes could produce high valence NOx such as N2O5 which should be more efficient for water activation, but this process is not easy to control stable, and the water activation by N2O5 has rarely been reported before. In this letter, N2O5 is found to be produced effectively and stably by mixing the effluent gases of a NOx mode air plasma, produced by gliding arc discharge, and an O3 mode air plasma, produced by dielectric barrier discharge, and the N2O5-rich mixed gas is found much efficient for water activation. Nearly 6 logs of CFU reduction are achieved for MRSA suspension by using the PAW treated by the mixed gas, and the PAW could persist a high bactericidal effect for more than one hour after the plasma activation. Main reactive species for bactericidal effect in the PAW are discussed, and the chemical pathways for N2O5 production and its usage for water activation are illustrated.
The COVID-19 pandemic is the most severe pandemic caused by a respiratory virus since the 1918 influenza pandemic. As is the case with other respiratory viruses, three modes of transmission have been invoked: contact (direct and through fomites), large droplets and aerosols. This narrative review makes the case that aerosol transmission is an important mode for COVID-19, through reviewing studies about bioaerosol physiology, detection of infectious SARS-CoV-2 in exhaled bioaerosols, prolonged SARS-CoV-2 infectivity persistence in aerosols created in the laboratory, detection of SARS-CoV-2 in air samples, investigation of outbreaks with manifest involvement of aerosols, and animal model experiments. SARS-CoV-2 joins influenza A virus as a virus with proven pandemic capacity that can be spread by the aerosol route. This has profound implications for the control of the current pandemic and for future pandemic preparedness.
Fungal aerosols in broiler houses are important factors that can harm the health of human beings and broiler. To determine the composite characteristics and changes in fungal aerosols in broiler houses during different broiler growth stages in summer. We analyzed the species, concentration and particle diameter distribution characteristics of the aerosols in poultry houses using an Andersen sampler and internal transcribed spacer 1 (ITS1) high-throughput sequencing technology. The concentration of fungal aerosols in the poultry houses increased as the ages of the broiler increased, which was also accompanied by gradual increases in the variety and diversity indices of the fungal communities in the air of the poultry houses. During the entire broiler growth period, the dominant genera in the fungal aerosols in the poultry houses included Trichosporon, Candida, Aspergillus, Cladosporium and Alternaria. These fungi may be harmful to the health of poultry and human beings, so permanent monitoring of microbial air quality in chicken houses is necessary.
Background
Urban air pollution is involved in the progress of idiopathic pulmonary fibrosis (IPF). Its potential role on the devastating event of Acute Exacerbation of IPF (AE-IPF) needs to be clarified. This study examined the association between long-term personal air pollution exposure and AE- IPF risk taking into consideration inflammatory mediators and telomere length (TL).
Methods
All consecutive IPF-patients referred to our Hospital from October 2013-June 2019 were included. AE-IPF events were recorded and inflammatory mediators and TL measured. Long-term personal air pollution exposures were assigned to each patient retrospectively, for O 3 , NO 2 , PM 2.5 [and PM 10 , based on geo-coded residential addresses. Logistic regression models assessed the association of air pollutants’ levels with AE-IPF and inflammatory mediators adjusting for potential confounders.
Results
118 IPF patients (mean age 72 ± 8.3 years) were analyzed. We detected positive significant associations between AE-IPF and a 10 μg/m ³ increase in previous-year mean level of NO 2 (OR = 1.52, 95%CI:1.15–2.0, p = 0.003), PM 2.5 (OR = 2.21, 95%CI:1.16–4.20, p = 0.016) and PM 10 (OR = 2.18, 95%CI:1.15–4.15, p = 0.017) independent of age, gender, smoking, lung function and antifibrotic treatment. Introduction of TL in all models of a subgroup of 36 patients did not change the direction of the observed associations. Finally, O 3 was positively associated with %change of IL-4 ( p = 0.014) whilst PM 2.5 , PM 10 and NO 2 were inversely associated with %changes of IL-4 ( p = 0.003, p = 0.003, p = 0.032) and osteopontin ( p = 0.013, p = 0.013, p = 0.085) respectively.
Conclusions
Long-term personal exposure to increased concentrations of air pollutants is an independent risk factor of AE-IPF. Inflammatory mediators implicated in lung repair mechanisms are involved.
Defective wound healing poses a significant burden on patients and healthcare systems. In recent years, a novel reactive oxygen and nitrogen species (ROS/RNS) based therapy has received considerable attention among dermatologists for targeting chronic wounds. The multifaceted ROS/RNS are generated using gas plasma technology, a partially ionized gas operated at body temperature. This review integrates preclinical and clinical evidence into a set of working hypotheses mainly based on redox processes aiding in elucidating the mechanisms of action and optimizing gas plasmas for therapeutic purposes. These hypotheses include increased wound tissue oxygenation and vascularization, amplified apoptosis of senescent cells, redox signaling, and augmented microbial inactivation. Instead of a dominant role of a single effector, it is proposed that all mechanisms act in concert in gas plasma-stimulated healing, rationalizing the use of this technology in therapy-resistant wounds. Finally, addressable current challenges and future concepts are outlined, which may further promote the clinical utilization, efficacy, and safety of gas plasma technology in wound care in the future.
Mechanisms of airborne transmission
The COVID-19 pandemic has highlighted controversies and unknowns about how respiratory pathogens spread between hosts. Traditionally, it was thought that respiratory pathogens spread between people through large droplets produced in coughs and through contact with contaminated surfaces (fomites). However, several respiratory pathogens are known to spread through small respiratory aerosols, which can float and travel in air flows, infecting people who inhale them at short and long distances from the infected person. Wang et al . review recent advances in understanding airborne transmission gained from studying the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and other respiratory pathogens. The authors suggest that airborne transmission may be the dominant form of transmission for several respiratory pathogens, including SARS-CoV-2, and that further understanding of the mechanisms underlying infection from the airborne route will better inform mitigation measures. —GKA
SARS-CoV-2 and other microbes within aerosol particles can be partially shielded from UV radiation. The particles refract and absorb light, and thereby reduce the UV intensity at various locations within the particle. Previously we demonstrated shielding in calculations of UV intensities within spherical approximations of SARS-CoV-2 virions within spherical particles approximating dried-to-equilibrium respiratory fluids. The purpose of this paper is to extend that work to survival fractions of virions (i.e., fractions of virions that can infect cells) within spherical particles approximating dried respiratory fluids, and to investigate the implications of these calculations for using UV light for disinfection. The particles may be on a surface or in air. Here, the survival fraction (S) of a set of individual virions illuminated with a UV fluence (F, in J/m²) is assumed described by S(kF)=exp(-kF), where k is the UV inactivation rate constant (m²/J). The average survival fraction (Sp) of the simulated virions in a group of particles is calculated using the energy absorbed by each virion in the particles. The results show that virions within particles of dried respiratory fluids can have larger Sp than do individual virions. For individual virions, and virions within 1-, 5-, and 9-µm particles illuminated (normal incidence) on a surface with 260-nm UV light, the Sp = 0.00005, 0.0155, 0.22 and 0.28, respectively, when kF=10. The Sp decrease to <10⁻⁷, <10⁻⁷, 0.077 and 0.15, respectively, for kF = 100. Results also show that illuminating particles with UV beams from widely separated directions can strongly reduce the Sp. These results suggest that the size distributions and optical properties of the dried particles of virion-containing respiratory fluids are likely important to effectively designing and using UV germicidal irradiation systems for microbes in particles. The results suggest the use of reflective surfaces to increase the angles of illumination and decrease the Sp. The results suggest the need for measurements of the Sp of SARS-CoV-2 in particles having compositions and sizes relevant to the modes of disease transmission.
Biofilms formed by multidrug-resistant bacteria are a major cause of hospital-acquired infections. Cold atmospheric-pressure plasma (CAP) is attractive for sterilization, especially to disrupt biofilms formed by multidrug-resistant bacteria. However, the underlying molecular mechanism is not clear. In this study, CAP effectively reduced the living cells in the biofilms formed by methicillin-resistant Staphylococcus aureus, and 6 min treatment with CAP reduced the S. aureus cells in biofilms by 3.5 log10. The treatment with CAP caused the polymerization of SaFtsZ and SaClpP proteins in the S. aureus cells of the biofilms. In vitro analysis demonstrated that recombinant SaFtsZ lost its self-assembly capability, and recombinant SaClpP lost its peptidase activity after 2 min of treatment with CAP. Mass spectrometry showed oxidative modifications of a cluster of peaks differing by 16 Da, 31 Da, 32 Da, 47 Da, 48 Da, 62 Da, and 78 Da, induced by reactive species of CAP. It is speculated that the oxidative damage to proteins in S. aureus cells was induced by CAP, which contributed to the reduction of biofilms. This study elucidates the biological effect of CAP on the proteins in bacterial cells of biofilms and provides a basis for the application of CAP in the disinfection of biofilms.
Severe acute respiratory syndrome coronavirus-2 (SAR-CoV-2) is a highly contagious infectious disease and spreads through aerosols and fomites. Health care personnel who are at the forefront of the fight against coronavirus disease-19 (COVID-19) pandemic are also at greater risk of contracting the infection. Mixing of uninfected people with infected people is potentially hazardous, especially in a radiology department. Implementation of meticulous operational changes, curtailment of nonurgent radiological work, rationalization of staff, equipment disinfection, use of personal protection equipment, and psychological support are needed to combat COVID-19 or any such infectious disease outbreak. This technical note will familiarize radiology workers with infectious disease outbreak-response to be adopted to ensure the safety of staff and patients.
Air pollution is a worrisome risk factor for global morbidity and mortality and plays a special role in many respiratory conditions. It contributes to around 8 million deaths/year, with outdoor exposure being responsible for more than 4.2 million deaths throughout the world, while more than 3.8 million die from situations related to indoor pollution. Pollutant agents induce several respiratory symptoms. In addition, there is a clear interference in numerous asthma outcomes, such as incidence, prevalence, hospital admission, visits to emergency departments, mortality, and asthma attacks, among others. The particulate matter group of pollutants includes coarse particles/PM10, fine particles/PM2.5, and ultrafine particles/PM0.1. The gaseous components include ground-level ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide. The timing, load, and route of allergen exposure are other items affecting allergic disease phenotypes. The complex interaction between pollutant exposures and human host factors has an implication in the development and rise of asthma as a public health problem. However, there are hiatuses in the understanding of the pathways in this disease. The routes through which pollutants induce asthma are multiple, and include the epigenetic changes that occur in the respiratory tract microbiome, oxidative stress, and immune dysregulation. In addition, the expansion of the modern Westernized lifestyle, which is characterized by intense urbanization and more time spent indoors, resulted in greater exposure to polluted air. Another point to consider is the different role of the environment according to age groups. Children growing up in economically disadvantaged neighborhoods suffer more important negative health impacts. This narrative review highlights the principal polluting agents, their sources of emission, epidemiological findings, and mechanistic evidence that links environmental exposures to asthma.
Objective:
To evaluate the microbial loading in aerosols produced after air-puff by non-contact tonometer (NCT) as well as the effect of alcohol disinfection on the inhibition of microbes and thus to provide suggestions for the prevention and control of COVID-19 in ophthalmic departments of hospitals or clinics during the great pandemics.
Methods:
A cross-sectional study was carried out in this study. A NIDEK NCT was used for intraocular pressure (IOP) measurement for patients who visited Department of Ophthalmology in Qilu Hospital of Shandong University during March 18-25 2020. After ultra-violate (UV) light disinfection, the room air was sampled for 5 minutes. Before and after alcohol disinfection, the air samples and nozzle surface samples were respectively collected by plate exposure method and sterile moist cotton swab technique after predetermined times of NCT air-puff. Microbial colony counts were calculated after incubation for 48 hours. Finally, mass spectrometry was performed for the accurate identification of microbial species.
Results:
Increased microbial colonies were detected from air samples close to NCT nozzle after air-puff compared with air samples at a distance of 1 meter from the nozzle (p = 0.001). Interestingly, none microbes were detected on the surface of NCT nozzle. Importantly, after 75% alcohol disinfection less microbes were detected in the air beside the nozzle (p = 0.003). Microbial species identification showed more than ten strains of microbes, all of which were non-pathogenic.
Conclusion:
Aerosols containing microbes were produced by NCT air-puff in the ophthalmic consultation room, which may be a possible virus transmission route in the department of ophthalmology during the COVID-19 pandemic. Alcohol disinfection for the nozzle and the surrounding air was efficient at decreasing the microbes contained in the aerosols and theoretically this prevention measure could also inhibit the virus. This will give guidance for the prevention of virus transmission and protection of hospital staff and patients.
As public health teams respond to the pandemic of coronavirus disease 2019 (COVID-19), containment and understanding of the modes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission is of utmost important for policy making. During this time, governmental regulators have been instructing resident with a series of physical distancing measures. However, currently there is no agreement on the role of aerosol transmission for SARS-CoV-2 among public health organizations from different countries. To this end, we aimed to review the evidences of aerosol transmission of SARS-CoV-2. Serval studies support that aerosol transmission of SARS-CoV-2 is plausible, and the plausibility (weight of combined evidence) is 8 out of 9, which is similar to SARS. Precautionary control strategies should consider aerosol transmission for effective mitigation of SARS-CoV-2.
Cold atmospheric pressure plasma has potential as a non-thermal processing technology to decontaminate food and food contact surfaces due to its ability to generate an abundance of reactive oxygen and nitrogen species with antimicrobial attributes at ambient conditions. In this study, we present a comparison on the effectiveness of surface decontamination against feline calicivirus (FCV) and Salmonella spp using four different plasma sources, a dielectric barrier discharge (DBD) in direct contact with the substrate and three remote plasma treatment sources: a 2D DBD, a volumetric DBD and a gliding arc discharge. The plasma sources were all operated in air at atmospheric pressure. The decontamination efficacy was enhanced by the presence of humidity on the sample surface and only direct contact between plasma and samples allowed the inactivation of pathogens on dry substrates. Across all sources, FCV was seen to be more susceptible to the plasma-generated species than Salmonella spp. The diminished effectiveness of the gliding arc discharge compared to the DBDs operating at the same power is most likely due to the low Henry's law constant of NO, the dominant reactive species generated by the gliding arc. Control experiments illustrate that the coexistence of O3 and NO2, as in the afterglow of the remote DBDs enhances the inactivation compared to the inactivation by O3 or NO2 only. A chemical kinetics model of the plasma effluent and the plasma treatments show a strong correlation between the gas-phase concentration of N2O5 and inactivation of the virus. We experimentally show that the production of N2O5 coincides with the enhanced generation of RNS in the liquid phase.
Viruses can infect all cell-based organisms, from bacteria to humans, animals, and plants. They are responsible for numerous cases of hospitalization, many deaths, and widespread crop destruction, which all result in an enormous medical, economical, and biological burden. Each of the currently used decontamination methods have important drawbacks. Cold plasma has entered this field as a novel, efficient, and clean solution for virus inactivation. Here, we present the recent developments in this promising field of cold-plasma-mediated virus inactivation, and describe the applications and mechanisms of the inactivation. This is a particularly relevant subject as viral pandemics, such as the COVID-19 pandemic, expose the need for alternative viral inactivation methods to replace, complement or upgrade existing ones.
Objectives:
We have developed a pulsed xenon ultraviolet light-based real-time air disinfection system with rapid and effective disinfection by using high-intensity pulse germicidal UV. Disinfection of the ambulance's environment is critical in the prevention of infectious cross contamination.
Methods:
In this study, a pulsed xenon ultraviolet light-based air disinfection system was established for real-time air disinfection in ambulances. In this system, a pulsed xenon ultraviolet (PX-UV) was used to generate broad-spectrum (200-320 nm), high-intensity ultraviolet light to deactivate and kill bacteria and viruses. The results showed that the use of PX-UV could be effective in reducing E. coli, Staphylococcus albus, and environmental pathogens level in ambulances (≥90% reduction in 30 mins).
Results:
This device was relatively simple and easy to use and does not leave chemical residues or risk exposing patients and workers to toxic chemicals.
Conclusions:
This appears to be a practical alternative technology to achieve automated air disinfection in ambulances.
Since the SARS outbreak 18 years ago, a large number of severe acute respiratory syndrome-related coronaviruses (SARSr-CoV) have been discovered in their natural reservoir host, bats1–4. Previous studies indicated that some of those bat SARSr-CoVs have the potential to infect humans5–7. Here we report the identification and characterization of a novel coronavirus (2019-nCoV) which caused an epidemic of acute respiratory syndrome in humans in Wuhan, China. The epidemic, which started from 12 December 2019, has caused 2,050 laboratory-confirmed infections with 56 fatal cases by 26 January 2020. Full-length genome sequences were obtained from five patients at the early stage of the outbreak. They are almost identical to each other and share 79.5% sequence identify to SARS-CoV. Furthermore, it was found that 2019-nCoV is 96% identical at the whole-genome level to a bat coronavirus. The pairwise protein sequence analysis of seven conserved non-structural proteins show that this virus belongs to the species of SARSr-CoV. The 2019-nCoV virus was then isolated from the bronchoalveolar lavage fluid of a critically ill patient, which can be neutralized by sera from several patients. Importantly, we have confirmed that this novel CoV uses the same cell entry receptor, ACE2, as SARS-CoV.
Emerging infectious diseases, such as SARS and Zika, present a major threat to public health1–3. Despite intense research efforts, how, when and where new diseases appear are still the source of considerable uncertainly. A severe respiratory disease was recently reported in the city Wuhan, Hubei province, China. Up to 25th of January 2020, at least 1,975 cases have been reported since the first patient was hospitalized on the 12th of December 2019. Epidemiological investigation suggested that the outbreak was associated with a seafood market in Wuhan. We studied one patient who was a worker at the market, and who was admitted to Wuhan Central Hospital on 26th of December 2019 experiencing a severe respiratory syndrome including fever, dizziness and cough. Metagenomic RNA sequencing4 of a bronchoalveolar lavage fluid sample identified a novel RNA virus from the family Coronaviridae, designed here as WH-Human-1 coronavirus. Phylogenetic analysis of the complete viral genome (29,903 nucleotides) revealed that the virus was most closely related (89.1% nucleotide similarity) to a group of SARS-like coronaviruses (genus Betacoronavirus, subgenus Sarbecovirus) previously sampled from bats in China. This outbreak highlights the ongoing capacity of viral spill-over from animals to cause severe disease in humans.
The 2017–2018 flu season is considered to be one of the most severe, with numerous influenza outbreaks worldwide. In an infectious disease hospital of Qinhuangdao, air samples were collected daily from outpatient hall, clinical laboratory, fever clinic, children's ward (Children's Ward I/Children's Ward II), and adult ward during 23–29 January 2018 (peak flu activity) and 9–15 April 2018 (low flu activity). The air samples were collected with SLC-SiOH magnetic beads using impingement samplers. Real-time PCR assay was used to detect the RNA of airborne influenza (IFVA and IFVB) in the 91 collected aerosol samples. The results indicated that the air samples collected from the children's wards, adult ward and fever clinic were detected with airborne influenza viruses. However, the samples collected from outpatient hall and clinical laboratory were absence of influenza viruses. In addition, the subtypes of pH1N1/IFVA, H3N2/IFVA, yamagata/IFVB, and victoria/IFVB were detected among the samples with positive IFVA and IFVB. Notably, a new developed subtype of pH1N1 (an epidemic in 2018) was detected in the aerosol samples. In summary, this study profiled the distribution of airborne influenza in an infectious hospital in Qinhuangdao during 2017–2018 flu season. Patients infected with influenza could release airborne particles containing the virus into their environment. Healthcare workers and visitors in those places might have frequent exposure to airborne influenza virus. Therefore, we recommend some protective measures such as air disinfection and mask wearing to prevent and control the transmission of airborne influenza in hospital.
The analysis of the gas phase chemistry of a cold atmospheric plasma is a fundamental step for a more thorough understanding of the effects it can induce on target substrates. This work aims at investigating, by means of optical spectroscopic techniques, the kinetics of O3, NO2 and NO3 produced by a Surface Dielectric Barrier Discharge. The phenomenon of discharge poisoning (or ozone quenching) in static ambient air was investigated varying the electrical power density applied to the plasma source. Kinetics of the reactive oxygen and nitrogen species production were obtained by means of time resolved UV/VIS optical absorption spectroscopy and highlighted how the discharge poisoning takes place once the applied power density ovecomes a critical value of 0.11 W cm⁻². An ozone-enriched atmosphere (with a maximum O3 density around 3000–4000 ppm) is thus obtained when the source is operated below the critical power density, while a NOx-enriched atmosphere (highest concentrations of NO2 around 1250 ppm and NO3 around 35 ppm) is obtained at higher applied power densities. Moreover, since the production of NO, one of the most important quenchers of O3, is directly related to the vibrational energy of nitrogen molecules, the vibrational population of N2, determined by processing emission spectra of N2(B → C) band, was studied. Finally, considerations regarding both the energy cost of production of a reactive oxygen species and reactive nitrogen species atmosphere and the possibility of on-line monitoring its chemical composition, were presented in order to emphasize the potential of optical absorption spectroscopy techniques for the on-line control of plasma assisted industrial processes.
Outbreaks of airborne infectious diseases such as measles or severe acute respiratory syndrome (SARS) can cause significant public alarm. Where ventilation systems facilitate disease transmission to humans or animals, there exists a need for control measures that provide effective protection while imposing minimal pressure differential. In the present study, viral aerosols in an airstream were subjected to non-thermal plasma (NTP) exposure within a packed-bed dielectric barrier discharge reactor. Comparisons of plaque assays before and after NTP treatment found exponentially increasing inactivation of aerosolized MS2 phage with increasing applied voltage. At 30 kV and an air flow rate of 170 standard liters per minute, a greater than 2.3-log reduction of infective virus was achieved across the reactor. This reduction represented ~2 log of the MS2 inactivated and ~0.35 log physically removed in the packed bed. Increasing the air flow rate from 170 to 330 LPM did not significantly impact virus inactivation effectiveness. Activated carbon-based ozone filters greatly reduced residual ozone, in some cases down to background levels, while adding less than 20 Pa pressure differential to the 45 Pa differential pressure across the packed bed at the flow rate of 170 standard liters per minute.
Although short-range large-droplet transmission is possible for most respiratory infectious agents, deciding on whether the same agent is also airborne has a potentially huge impact on the types (and costs) of infection control interventions that are required.
The concept and definition of aerosols is also discussed, as is the concept of large droplet transmission, and airborne transmission which is meant by most authors to be synonymous with aerosol transmission, although some use the term to mean either large droplet or aerosol transmission.
However, these terms are often used confusingly when discussing specific infection control interventions for individual pathogens that are accepted to be mostly transmitted by the airborne (aerosol) route (e.g. tuberculosis, measles and chickenpox). It is therefore important to clarify such terminology, where a particular intervention, like the type of personal protective equipment (PPE) to be used, is deemed adequate to intervene for this potential mode of transmission, i.e. at an N95 rather than surgical mask level requirement.
With this in mind, this review considers the commonly used term of ‘aerosol transmission’ in the context of some infectious agents that are well-recognized to be transmissible via the airborne route. It also discusses other agents, like influenza virus, where the potential for airborne transmission is much more dependent on various host, viral and environmental factors, and where its potential for aerosol transmission may be underestimated.
The United Nations Environment Programme (UNEP) convened the Minamata Convention on Mercury in 2013 to ban mercury-containing products in order to ensure human and environmental health. It will be effectuated in 2020 to discontinue use of low-pressure mercury lamps and new UV-emitting sources have to replace this conventional technology. However, the UV germicidal irradiation (UVGI) system still uses conventional UV lamps, and no research has been conducted for air disinfection using UVC LEDs. The research reported here investigated the inactivation effect of aerosolized microorganisms, including viruses, bacteria, and fungi, with an UVC LED module. The results can be utilized as a primary database to replace conventional UV lamps with UVC LEDs, a novel type of UV emitter. Implementation of UVC LED technology is truly expected to significantly reduce the extent of global mercury contamination, and this study provides important baseline data to help ensure a healthier environment and increased health for humanity.
Pandemic and seasonal influenza viruses can be transmitted through aerosols and droplets, in which viruses must remain stable and infectious across a wide range of environmental conditions. Using humidity-controlled chambers, we studied the impact of relative humidity on the stability of 2009 pandemic influenza A(H1N1) virus in suspended aerosols and stationary droplets. Contrary to the prevailing paradigm that humidity modulates the stability of respiratory viruses in aerosols, we found that viruses supplemented with material from the apical surface of differentiated primary human airway epithelial cells remained equally infectious for 1 hour at all relative humidities tested. This sustained infectivity was observed in both fine aerosols and stationary droplets. Our data suggest, for the first time, that influenza viruses remain highly stable and infectious in aerosols across a wide range of relative humidities. These results have significant implications for understanding the mechanisms of transmission of influenza and its seasonality.
Background
Disinfection of shared spaces has become essential to minimize the spread of various diseases. An efficient disinfection device that can simultaneously inactivate airborne bacteria and surface adhered bacteria in an enclosed space is required.
Aim
An air-passable plasma filter (APF) was developed and applied to a chamber model to evaluate the zone-disinfection effect.
Methods
The 60 litre chamber consisted of a nebulizer, circulation fans, temperature and humidity monitors, an air sampling port with a sealed gate, airborne bacteria trapping media, and a built-in fan for evaluation. After spraying each bacterial strain (Escherichia coli, Staphylococcus epidermidis, and Mycobacterium smegmatis) as a bioaerosol, airborne and surface-attached bacteria were quantified simultaneously to evaluate the zone-disinfection effect of APF.
Findings
The operation of APF in the 60 litre chamber showed a complete zone-disinfection effect for E. coli (10 min), S. epidermidis (10 min), and M. smegmatis (60 min) present in the air and on the walls at various locations. The time required to completely disinfect each of the airborne bacteria and surface-attached bacteria within the same space was different.
Conclusion
APF has the potential to exhibit significant germicidal effects on various microorganisms and can be an effective alternative for disinfection of enclosed spaces.
Water contamination through anthropogenic and industrial activities has led to the emergence and necessity of disinfection methods. Chlorine and bromine gases, often used to disinfect water, resulted in the by-product formation by reacting with organic matter. The Disinfectant by-products (DBP) led to the formation of Trihaloaceticacid (TAA), Trihalomethane (THM), and other minor components. The release of chemicals has also led to the outbreak of diseases like infertility, asthma, stillbirth, and types of cancer. There are new approaches that are found to be useful to compensate for the generation of toxic by-products and involve membrane technologies, namely reverse osmosis, ultrafiltration, and nanofiltration. This review mainly focuses on the toxicology effects of DBPs and various approaches to mitigate the same. The health hazards caused by different DBPs and the various treatment techniques available for the removal are discussed. In addition, a critical comparison of the different removal techniques was discussed.
Yersinia enterocolitica is a pervasive pathogen associated with foodborne infections. Citral is an FDA-certified food safety ingredient derived from plants because citral has antioxidant, antibacterial and anticancer properties. This study was conducted to investigate the antibacterial activity of citral against Y. enterocolitica and its possible antimicrobial mechanism. The minimum inhibitory concentrations (MIC) and minimal bactericidal concentration (MBC) of citral against Y. enterocolitica ATCC 23715 were 0.2 and 0.4 mg/mL, respectively, and Y. enterocolitica treated with citral showed an obvious reduction in growth rate compared with an untreated control. Citral was also found to increase the level of reactive oxygen species in cells, induce morphological changes in cells, and cause cell membrane dysfunction, as evidenced by cell membrane hyperpolarization, decreased cell membrane integrity and intracellular ATP concentration. Sodium dodecyl sulfate-poly-acrylamide gel electrophoresis (SDS-PAGE) analysis confirmed the effects of citral on proteins synthesis by Y. enterocolitica, while reverse transcription-quantitative real-time PCR (RT-qPCR) indicated that the transcription of multiple genes associated with virulence of Y. enterocolitica, such as ail, myfA, ystA, pspB, phoQ and gsrA, was reduced by citral. Moreover, citral effectively inactivated Y. enterocolitica in PBS, LB broth, and fresh vegetable juice. These findings suggest that citral has the potential for use as a natural antimicrobial agent to control Y. enterocolitica in vegetables and other areas of the food supply chain, thereby reducing the risk of Y. enterocolitica infection.
Airborne transmission of antibiotic resistance genes (ARGs) has emerged as a global health threat, while their hosts’ resistance phenotype remains largely unknown. Here, culturable bacterial aerosol samples were collected from polluted air in Beijing using a portable high volume sampler (1000 L/min). Antimicrobial susceptibility testing was conducted to explore the antibiotic sensitivity of culturable bacterial aerosols to seven widely used antibiotics. As a comparison, ARG distribution and expression in two human respiratory pathogenic bacterial strains (Pseudomonas aeruginosa and Methicillin-resistant Staphylococcus aureus) and a non-pathogenic bacterial strain (Pseudomonas fluorescens) were also studied. Relative abundances of 39 ARG subtypes in three bacterial strains including Haemophilus influenzae were investigated by high throughput real-time qPCR platform. Surprisingly, 53.05% of airborne culturable bacteria in polluted air were susceptible to ampicillin (β-lactams), while 24.66% of the culturable bacterial aerosols were resistant to vancomycin-the most powerful antibiotics to date. Different bacteria demonstrated very different ARG distribution patterns of more or less skewed toward certain one ARG type. On the other hand, the vancomycin resistance gene vanB was detected both in H. influenza and P. fluorescens, however these bacteria did not exhibit anti-vancomycin phenotype. Furthermore, the resistance to ciprofloxacin (quinolones) was not observed in P. aeruginosa and P. fluorescens although these bacteria harbor abundant quinolone resistance gene qepA. Experimental data from this work show that air represents an important active reservoir of diverse ARGs, and some bacterial aerosols are harboring vancomycin resistance gene though not expressed. Results from human respiratory pathogens have further demonstrated similar findings. This work underscores the serious concern of airborne dissemination of ARBs including those resistant to vancomycin in polluted ambient environments, while revealing abundances and patterns of various ARGs in both pathogenic and non-pathogenic bacteria.
Background
The concern with environmental security to avoid contamination of people was intensified with the crisis established by SARS-CoV-2. The COVID-19 pandemic has shown the necessity to create systems and devices capable of clearing the air of an environment from microorganisms more efficiently. The development of systems that allow removing micro-droplets mainly originated from breathing or talking from the air was the motivation of this study. Aim: This article describes a portable and easy-to-operate system that helps to eliminate the droplets or aerosols present in the environment by circulating air through a UV-C reactor. Methods: We described the development of an air circulation device, and we performed a proof-of-principle study using the device against bacteria in simulated and natural environments. The microbiological analysis was carried out by the simple sedimentation technique. For comparing the experimental results and the expected results for other microorganisms, the reduction rate values for bacteria and viruses were calculated and compared to the experimental results based on technical parameters (CADR and ACH). Findings: Results showed the microorganisms were eliminated with high efficiency by the air circulation decontamination device, with reductions of 99.9% in the proof-of-principle study, and 84% to 97% at hospital environments study, contributing to reduce people contamination in environments considered to offer risk. Conclusion: This study resulted in a low-cost and relatively simple device, which showed to be effective and safe. It can be replicated, especially in low-income countries, respecting the standards for air disinfection using UV-C technologies.
Disinfection is considered as a vital step to ensure the supply of clean and safe drinking water. Various approaches are adopted for this purpose; however, chlorination is highly preferred all over the world. This method is opted owing to its several advantages. However, it leads to the formation of certain by-products. These chlorination disinfection by-products (DBPs) are genotoxic, carcinogenic and mutagenic. Still chlorination is being practiced worldwide. Present review gives insights into the occurrence, toxicity and factors affecting the formation of regulated (THMs, HAAs) and emerging DBPs (N-DBPs, HKs, HAs and aromatic DBPs) found in drinking water. Furthermore, remediation techniques used to control DBPs have also been summarized here. Key findings are: (i) concentration of regulated DBPs surpassed the permissible limit in most of the regions, (ii) high chlorine dose, high NOM, more reaction time (up to 3 hours) and high temperature (up to 30°C) enhance the formation of THMs and HAAs, (iii) high pH favors the formation of THMs while low pH is suitable of the formation of HAAs, (iv) high NOM, low temperature, low chlorine dose and moderate pH favors the formation of unstable DBPs (N-DBPs, HKs and HAs), (v) DBPs are toxic not only for humans but for aquatic fauna as well, (vi) membrane technologies, enhanced coagulation and AOPs remove NOM, (vii) adsorption, air stripping and other physical and chemical methods are post-formation approaches (viii) step-wise chlorination is assumed to be an efficient method to reduce DBPs formation without any treatment. Toxicity data revealed that N-DBPs are found to be more toxic than C-DBPs and aromatic DBPs than aliphatic DBPs. In majority of the studies, merely THMs and HAAs have been studied and USEPA has regulated just these two groups. Future studies should focus on emerging DBPs and provide information regarding their regulation.
Recently, the potential dangers of viral infection transmission through water and air have become the focus of worldwide attention, via the spread of COVID-19 pandemic. The occurrence of large-scale outbreaks of dangerous infections caused by unknown pathogens and the isolation of new pandemic strains require the development of improved methods of viruses’ inactivation. Viruses are not stable self-sustaining living organisms and are rapidly inactivated on isolated surfaces. However, water resources and air can participate in the pathogens’ diffusion, stabilization, and transmission. Viruses inactivation and elimination by adsorption are relevant since they can represent an effective and low-cost method to treat fluids, and hence limit the spread of pathogen agents. This review analyzed the interaction between viruses and carbon-based, oxide-based, porous materials and biological materials (e.g., sulfated polysaccharides and cyclodextrins). It will be shown that these adsorbents can play a relevant role in the viruses removal where water and air purification mostly occurring via electrostatic interactions. However, a clear systematic vision of the correlation between the surface potential and the adsorption capacity of the different filters is still lacking and should be provided to achieve a better comprehension of the global phenomenon. The rationalization of the adsorption capacity may be achieved through a proper physico-chemical characterization of new adsorbents, including molecular modeling and simulations, also considering the adsorption of virus-like particles on their surface. As a most timely perspective, the results on this review present potential solutions to investigate coronaviruses and specifically SARS-CoV-2, responsible of the COVID-19 pandemic, whose spread can be limited by the efficient disinfection and purification of closed-spaces air and urban waters.
One of the major concerns in the COVID‐19 pandemic is related to the possible transmission in poorly ventilated spaces of SARS‐CoV‐2 through aerosol microdroplets, which can remain in the air for long periods of time and be transmitted to others over distances >1 m. Cold atmospheric pressure plasmas can represent a promising solution, thanks to their ability in producing a blend of many reactive species, which can inactivate the airborne aerosolized microorganisms. In this study, a dielectric barrier discharge plasma source is used to directly inactivate suitably produced bioaerosols containing Staphylococcus epidermidis or purified SARS‐CoV‐2 RNA flowing through it. Results show that for low residence times (<0.2 s) in the plasma region a 3.7 log R on bacterial bioaerosol and degradation of viral RNA can be achieved. A dielectric barrier discharge is used to directly inactivate bioaerosols containing Staphylococcus epidermidis or purified SARS‐CoV‐2 RNA flowing through it.
Most previous studies on aerosols have focused on the role of aerosols in the transmission of human and animal pathogens; however, little is known about the role of aerosols in the transmission of plant bacterial disease. In this study, experimental evidence for the emission and transmission of Pseunomonas. amygdali pv. lachrymans (Pal) aerosol was provided, and the results supported that diseased cucumber plants served as the main source of Pal aerosol. Bacterial aerosols released by infected plants played a significant role in the epidemiology of cucumber angular leaf spot (ALS) disease. Aerosol chambers were constructed to study the characteristics of Pal aerosols released by artificially infested cucumber plants. The particle size of Pal aerosol was predominately distributed from 1.1 to 4.7 μm, accounting for 72.16% of the total amount of Pal aerosol. The infection threshold of aerosolized Pal to cause ALS disease was 84–179 CFU/m³. In addition, the transmission dynamics of Pal aerosols from donor cucumber plants to recipient cucumber plants were also confirmed in exposure chambers and greenhouses. The results from the present study verified the hypothesis that aerosol dissemination is a potential route for the epidemiology of plant bacterial disease, and these data will contribute to the development of new strategies for the effective alleviation and control of plant bacterial diseases.
Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2(SARS-CoV-2) has created a significant threat to global health. It originated in Wuhan, China and causeda total of 83,483 confirmed cases and 4634 deaths until June 2020. This novel virus spread primarilythrough respiratory droplets and close contact. The person-to-person transmission by direct transmit-tance through cough, sneeze, droplet inhalation, and contact spreading from dry surfaces contami-nated with secretions of nose, mouth, and eyes of an infected person has been proven about SARS-CoV-2 transmission. As disease progressed, a series of complications tends to develop, especially in crit-ically ill and immunocompromised patients. Pathological studies showed representative features ofacute respiratory distress syndrome (ARDS) and implications on multiple organs as well. However, nospecific antiviral drugs or vaccines are immediately available for the treatment of this lethal disease.The efficacy of some promising antivirals needs to be investigated by ongoing clinical trials. In currentcircumstances, supportive care, precautions, and social distancing are the only preventive options toameliorate COVID-19. To disinfect the environment, mainly chemical disinfectants are being usedrobustly. However, due to panic state, fright, and unawareness, people are using it violently, which canhave an adverse effect on human health and environment. This review discusses about the potentialharmful effect of disinfectants, if used inappropriately. Here, we will also discuss safe preventiveoptions as an alternative to robust use of disinfection methods to fight against COVID-19.
The recent coronavirus 2019 (COVID-19) pandemic has resulted in increased hand hygiene and hand cleansing awareness. To prevent virus transmission, the Center for Disease Control (CDC) recommends frequent hand washing with soap and water. Hand hygiene products are available in a variety of forms and while each of these formulations may be effective against COVID-19, they may also alter skin barrier integrity and function. As health care workers and the general population focus on stringent hand hygiene, the American Contact Dermatitis Society (ACDS) anticipates an increase in both irritant contact and allergic contact hand dermatitis. Alcohol-based hand sanitizers with moisturizers have the least sensitizing and irritancy potential when compared to soaps and synthetic detergents. This article provides an overview of the most frequently used hand hygiene products and their associations with contact dermatitis as well as recommendations from the ACDS on how to treat and prevent further dermatitis.
The pandemic of coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has posed a severe threat to global public health. Yet, the origin of SARS-CoV-2 remains mysterious. Several recent studies (e.g., Lam et al., Xiao et al.) identified SARS-CoV-2-related viruses in pangolins, providing novel insights into the evolution and diversity of SARS-CoV-2-related viruses.
Ebola virus (EBOV) disease outbreaks, as well as the ability of EBOV to persist in the environment under certain conditions, highlight the need to develop effective decontamination techniques against the virus. We evaluated the efficacy of hydrogen peroxide vapor (HPV) to inactivate MS2 and Phi6 bacteriophages, the latter a recommended surrogate for EBOV. The phages were inoculated onto six material types with and without the presence of whole human blood. The inoculated materials were then exposed to either a high or low concentration of HPV for various elapsed times. The phages were also recovered from positive controls at these same elapsed times, to assess environmental persistence and decontamination efficacy. Low concentration hydrogen peroxide vapor (LCHP; 25 ppm) was effective against both phages on all materials without the presence of blood at 2 h. LCHP was ineffective against the phages in the presence of blood, on all materials, even with a 3-day contact time. Higher concentrations of HPV (> 400 ppm) with contact times of 24-32 h achieved approximately 2-6 log reduction of the phages in the presence of blood.
Introduction: Sodium hypochlorite is used as a bleaching and disinfecting agent and is commonly found in household bleach.
Objective: The objective is to review critically the epidemiology, mechanisms of toxicity, clinical features, diagnosis, and management of hypochlorite poisoning.
Methods: PubMed was searched from January 1950 to June 2018 using the terms “Hypochlorite”, “Sodium Hypochlorite”, “Sodium Oxychloride”, “Hypochlorous Acid”, “Bleach”, “Chlorine Bleach”, in combination with the keywords “poisoning”, “poison”, “toxicity”, “ingestion”, “adverse effects”, “overdose”, and “intoxication”. In addition, bibliographies of identified articles were screened for additional relevant studies including non-indexed reports. Non-peer-reviewed sources were also included. These searches produced 110 citations which were considered relevant.
Epidemiology: There is limited information regarding statistical trends on world-wide poisoning from sodium hypochlorite. In the United States of America, poison control center data have shown that enquiries regarding hypochlorite bleaches have ranged from 43,000 to 46,000 per year over the period 2012–2016.
Mechanisms of toxicity: Hypochlorite’s potential to cause toxicity is related to its oxidizing capacity and the pH of the solution. Toxicity arises from its corrosive activity upon contact with mucous membranes and skin.
Features following ingestion: While small accidental ingestions are very unlikely to cause clinically significant toxicity, large ingestions may cause corrosive gastrointestinal injury and systemic effects, including metabolic acidosis, hypernatremia, and hyperchloremia.
Features following dental exposure: Hypochlorite is used extensively by dentists for cleaning root canals and is safe if the solution remains within the root canal. Extrusions into the periapical area can result in severe pain with localized large and diffuse swelling and hemorrhage.
Features following skin exposure: Prolonged or extensive exposure may cause skin irritation and damage to the skin or dermal hypersensitivity. Such exposures can result in either immediate or delayed-type skin reactions. High concentration solutions have caused severe chemical skin burns.
Features following inhalation: Although there are only limited data, inhalation of hypochlorite alone is likely to lead to no more than mild irritation of the upper airways.
Features following ocular exposure: Corneal injuries from ocular exposure are generally mild with burning discomfort and superficial disturbance of the corneal epithelium with recovery within 1 or 2 days. With higher concentration solutions, severe eye irritation can occur.
Diagnosis: The diagnosis can typically be made on the basis of a careful history, including details of the specific product used, its hypochlorite concentration, and the amount involved. As hypochlorite bleach produces a characteristic smell of chlorine, this may provide a diagnostic clue. In severe cases, corrosive injury is suggested on presentation because of hypersalivation, difficulty swallowing, retrosternal pain or hematemesis.
Management: Symptom-directed supportive care is the mainstay of management. Gastrointestinal decontamination is not beneficial. Local corrosive injury is the major focus of treatment in severe cases. Fiberoptic endoscopy and CT thorax/abdomen are complimentary and have been shown to be useful in corrosive injuries in assessing the severity of injury, risk of mortality and risk of subsequent stricture formation and should be performed as soon as possible after ingestion. Dental periapical extrusion injuries should be left open for some minutes to allow bleeding through the tooth and to limit hematoma development in tissue spaces. Once the bleeding has ceased, the canal can be dressed with non-setting calcium hydroxide and sealed coronally.
Conclusions: Accidental ingestion of household bleach is not normally of clinical significance. However, those who ingest a large amount of a dilute formulation or a high concentration preparation can develop severe, and rarely fatal, corrosive injury so prompt supportive care is essential as there is no specific antidote. Treatment primarily consists of symptom-directed supportive care.
The inactivation of viruses that retain their infectivity when transmitted through the air is challenging. To address this issue, this study used a non-contact ultrasound transducer (NCUT) to generate shock waves in the air at specific distances, input voltages, and exposure durations, targeting bacteriophage virus aerosols captured on to H14 HEPA filters. Initially, a frequency of 27.56 kHz (50V) at 25-mm distance was used, which yielded an inactivation efficiency of up to 32.69 ± 12.10%. Other frequencies at shorter distances were investigated, where 29.10 kHz had the highest inactivation efficiency (up to 81.95 ± 9.79% at 8.5-mm distance and 100 V). Longer exposure times also influenced virus inactivation, but the results were inconclusive because the NCUT overheated with time. Overall, NCUT appears to be a promising method for inactivating virus aerosols that may be safer than other forms of inactivation, which can cause genetic mutations or produce dangerous by-products.