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The Air borne transmission is a very big concern for highly infectious diseases like Covid-19 and other airborne diseases. A micro droplet and aerosol can be carried out in the air and can remain flowing in air over a distance in a confined space, leading to affecting high number of people getting prone to infection and it is very dangerous in enclosed spaces or shared spaces. Public places, shared facilities are the areas, where infectious aerosol can be present in the air for a long duration. Ventilation of closed spaces, shared spaces is the need of hour to have analysed and deep study in context of infectious airborne diseases. Introduction of fresh air into the enclosed environment at regular interval of times may lead to fast dilution of air present in the enclosed space. The prominent building codes and HVAC guidelines allows as to calculate ACPH (Air changes per hour) in an enclosed space as per the occupancy and flow rate. The age of air is the criteria to define the amount of air residing in the enclosed space when it enters the space till its exhaust from that space. The more the age of air in the particular area the more can be the infection probability among the occupants. It is predominant to study the airflow pattern caused due to ventilation which can be collaborated with age of air to know about the infection probability. Typically, a classroom geometry is assumed with inlet outlet boundary conditions where exhaust fan is playing a major role of displacement ventilation. Study of air recirculation zones and dead zones is the point of interest of this study. Computational fluid dynamics is the most powerful tool in the present era to study the air flow pattern in enclosed and shared spaces.Copyright © 2022, Anka Publishers. All rights reserved.
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Herein, we establish a novel isothermal digital amplification system termed digital nicking and extension chain reaction system-based amplification (dNESBA) by utilizing the isothermal NESBA technique and the newly developed miniaturized fluorescence monitoring system (mFMS). dNESBA enables parallel isothermal NESBA reactions in more than 10,000 localized droplet microreactors and read the fluorescence signals rapidly in 150 s by mFMS. This system could identify the genomic RNA (gRNA) extracted from target respiratory syncytial virus A (RSV A) as low as 10 copies with remarkable specificity. The practical applicability of dNESBA was also successfully verified by reliably detecting the gRNA in the artificial sputum samples with excellent reproducibility and accuracy. Due to the intrinsic advantages of isothermal amplifying technique including the elimination of the requirement of thermocycling device and the enhanced portability of the miniaturized read-out equipment, the dNESBA technique equipped with mFMS could serve as a promising platform system to achieve point-of-care (POC) digital molecular diagnostics, enabling absolute and ultra-sensitive quantification of various infectious pathogens even in an early stage.Copyright © 2023
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The outbreak of coronavirus disease 2019 (COVID-19) in December 2019 was associated with new challenges in many fields of medicine. Preventing transmission of the virus and infection of professional healthcare workers became of major concern in our daily clinical practice during the pandemic. Viral particles within aerosols can be detected up to 3h after aerosolization. Recent work defined endoscopic procedures of the upper gastrointestinal tract as being aerosol-generating procedures (AGPs);thus, they can carry the possibility of transmitting airborne viruses to personnel. Because severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is primarily transmitted by aerosols and/or droplets, the use of personal protective equipment (PPE) is warranted. Guideline recommendations from the WHO and other societies were also modified early to include PPE as an infection prevention measure. The strict use of PPE has proven to be an effective prevention strategy over the 3 years since its implementation. With the introduction of vaccinations against SARS-CoV-2, increasing immunization of the population, and a changing pandemic infection pattern, the requirements for endoscopic departments in hospitals and outpatient care settings continued to change. In the postpandemic situation, there are only minor restrictions that affect the new "postpandemic reality", thus, allowing endoscopic services to be performed without major restrictions. Here, we present a review of recent and most relevant knowledge to summarize the prophylactic measures that must be taken to perform endoscopy under safe conditions during the COVID-19 pandemic.Copyright © 2023, The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.
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Understanding of the droplet transmission of respiratory diseases is necessary to control the outbreak of COVID-19. HVAC systems considering droplet transmission are commonly used to prevent numerous respiratory diseases by reducing indoor virus concentrations. The transmission of the virus was directly related to indoor flow patterns generated by HVAC systems. Thus, a study on operating conditions such as direction or the tilt angle was required. In this study, the effective ventilation rate and probability of droplet transmission according to the tilt angle of supply air and the number of people were studied. A CO2 tracer gas method was used to validate the results of simulations. The breathing plane and personal respiratory zone were introduced for the probability of droplet transmission. The result showed that ventilation performance showed 17% of the maximum difference among tilt angles. Various turbulent kinetic energies were obtained according to the seated positions, resulting in non-uniform CO2 concentration. Numerous conditions were examined with locational analysis of individuals. As a result, the flow rates for ventilation were recommended to be higher than 250 m3/h and 350 m3/h with a tilt angle of 60degree for an occupancy of 8 and 16 people, respectively.Copyright © The Author(s) 2022.
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This paper presents a position statement on combining computational fluid dynamics (CFD) and ergonomics to guide the design of personal protective equipment (PPE). We used CFD to simulate 36 exposure scenarios of an infected patient sneezing at different distances and different angles while facing either the front or the side of a healthcare worker with or without goggles. The results show that medical goggles indeed block most droplets from the outer surface, but many droplets still deposit on the bottom edge (especially at the nose), inside the air holes and on the side edge. However, the edges of medical goggles have fitment problems with people in different regions, and the air holes do not function as filters and cannot prevent fine droplets from entering the interior and contacting the eyes. Our research demonstrates the feasibility of studying the design of PPE for airtightness and protection by means of CFD.Practitioner summary: Computational fluid dynamics can quickly and efficiently reflect the airtightness design problems of PPE. A model was developed using CFD to examine the protective effect of medical goggles in preventing the airborne transmission of viruses. The model demonstrates the feasibility of using CFD to solve ergonomic problems.Abbreviations: CFD: computational fluid dynamics; PPE: personal protective equipment; WHO: the World Health Organisation; COVID-19: coronavirus disease 2019; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; OSHA: the Occupational Safety and Health Administration; CDC: the Centres for Disease Control; FEM: finite element method; 3M: Minnesota Mining and Manufacturing Corporation; SPH: smoothed particle hydrodynamics; AROM: active range of motion; DPM: discrete phase model; PISO: pressure implicit with splitting of operators; VR: virtual reality; AR: augmented reality.
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Purpose: Various infectious diseases have dramatically decreased during the COVID-19 pandemic. In Japan, the most frequent cause of HLH in children and adolescents and young adults was infection. In this study, we assessed the incidence of six hematological diseases including HLH, before and during the COVID-19 pandemic Methods:We analyzed the public dataset from the Blood Disease Registration maintained by the Japanese Society of Hematology. From 2016 to 2019, the mean number of patients registered was 42,406 +/- 5,046. In 2020, this figure was 46,471. To analyze changes in annual incidence, we calculated the mean and standard deviation for the 2016-2019 data, and compared this to the annual incidence of each disease in 2020 Results: The total incidence of HLH decreased to 73.7%, compared with the 2016-2019 mean incidence of HLH (152.0 vs. 206.3+/-10.2) Furthermore, HLH incidence in 2020 decreased by 77.5% in those less than 20 years old, and 77.9% in those over 20 years old. Similarly the incidence of IM and aITP decreased by 91.5% and 78.4% in 2020, compared to the respective mean incidences of IMand aITP from 2016 to 2019. The decrease in the number of IM and aITP patients was larger among those less than 20 years of age, compared to those 20 years of age or older (IM: 84.8% vs. 96.6%, and aITP: 52.6% vs 106.5%). On the other hand, the incidences of LCH, ALL, and B-NHL did not decrease in 2020 (LCH, 109.9%;ALL, 102.9%;and B-NHL 111.9%). CONCLUSION(S): The incidence of HLH decreased during the COVID-19 pandemic. Lifestyle changes may be implemented during theCOVID-19 pandemic, specifically social distancing, wearing of facemasks alcohol disinfection, and school closure, effectively reduced contact and droplet transmission.
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Safe social distance is an important parameter for the prevention and treatment of a virus transmitted through droplets. However, the distance selected is not suitable for all air environments, and the calculation method of fluid research is time-consuming. Therefore, rapid and accurate prediction of safe social distance is the key to epidemic prevention and control. However, it is difficult for the existing fluid research to obtain the safe social distance rapidly. In this study, we set up a simple and effective numerical model and develop codes that combine the effects of evaporation, drag force, and gravity. We further conducted numerical simulations to investigate the motion of droplets in various air conditions. We completed a single case simulation with only one core and within several minutes, and determined that the resistance time and velocity evolution directly impact the transmission distance. We also observed two-stage regularity of motions in both the vertical and horizontal directions, and competition between evaporation and vertical falling. In addition, we derived a set of analytical solutions to describe the evaporation time and vertical and horizontal distances. The results demonstrated the good accuracy of the predicted data. Herein, we obtained an approximate rather than an accurate solution and, together with empirical coefficients, fitted it based on our numerical simulation. The proposed method can provide a rapid and accurate estimation of safe social distances for various environmental conditions. Common clinical cases were also analyzed, and prevention and control recommendations were provided based on the outcomes of the study. © 2023 Elsevier Ltd
ABSTRACT
Understanding of the droplet transmission of respiratory diseases is necessary to control the outbreak of COVID-19. HVAC systems considering droplet transmission are commonly used to prevent numerous respiratory diseases by reducing indoor virus concentrations. The transmission of the virus was directly related to indoor flow patterns generated by HVAC systems. Thus, a study on operating conditions such as direction or the tilt angle was required. In this study, the effective ventilation rate and probability of droplet transmission according to the tilt angle of supply air and the number of people were studied. A CO2 tracer gas method was used to validate the results of simulations. The breathing plane and personal respiratory zone were introduced for the probability of droplet transmission. The result showed that ventilation performance showed 17% of the maximum difference among tilt angles. Various turbulent kinetic energies were obtained according to the seated positions, resulting in non-uniform CO2 concentration. Numerous conditions were examined with locational analysis of individuals. As a result, the flow rates for ventilation were recommended to be higher than 250 m(3)/h and 350 m(3)/h with a tilt angle of 60 degrees for an occupancy of 8 and 16 people, respectively.
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Background and Objective Coronaviruses are a family of viruses that can cause respiratory illness in humans. They are called “corona” because of crown-like spikes on the surface of the virus. Severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS) and the common cold are examples of coronaviruses that cause illness in humans. The primary mode of transmission of SARS-CoV-2 is via exposure to respiratory droplets carrying the infectious virus from close contact or droplet transmission from presymptomatic, asymptomatic, or symptomatic individuals harbouring the virus This study is conducted to analyse the extent of association between COVID-19 & Diabetes Mellitus and its correlation with the inflammatory markers as it is still unclear if diabetes interferes in the prognosis of COVID-19 Material & Methods A Cross-sectional study was conducted over a period of 6 months from April 2021–September 2021.Among 149 RT-PCR positive COVID-19 patients the random blood sugar levels, CT chest severity score & C-Reactive Protein was compared among the diabetic & non-diabetic population in ACS Medical college & hospital Chennai. Results The study shows that out of 149 COVID-19 positive patients, 88 (59.1%) were diabetic & 61 (40.9%) were non-diabetic. Patients with diabetes had significantly higher CT chest severity score and elevated C-reactive protein than non-diabetic patients. Conclusion The interaction between covid-19 & diabetes could be bi-directional, with SARS-CoV-2 potentially worsening pre-existing diabetes.
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Introduction and Aim: Healthcare workers (HCWs) are always at a risks of contacting infection due to their frequent exposure to infected individuals. Knowledge regarding various infection control practices especially in this pandemic era is mandatory to safeguard the HCWs. An interventional study was carried out to assess the level of knowledge of Infection control practices and standard precautions with especial reference to COVID-19 among the health care workers of a tertiary care teaching Hospital. Materials and Methods: A total of 202, undergraduate students (UGs), post graduate students (PGs) and non-teaching staff (NTS) participated in this study. A pre-test self-structured questionnaire regarding infection control practices and standard precautions with especial reference to COVID-19 was distributed to all the participants. The study participants were then trained by faculty of Microbiology and infection control team vigorously. The post-training questionnaire was subsequently given to the same group of subjects. The data from before and after training was evaluated and compared. Results: On post-training evaluation after intervention, there was a significant increase in knowledge of various infection control practices among HCWs, as seen by comparing the results of the post-test questionnaire to its pre-test counterpart, because the HCWs' doubts were cleared in the education sessions. Conclusion: The knowledge regarding the various infection control practices among the HCWs is short lived and significant increase was observed on post training. The health care settings should make a policy to carry out mandatory rotational repeated trainings by the Infection control team for all the groups of HCWs for better compliance.
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The question of whether SARS-CoV-2 is mainly transmitted by droplets or aerosols has been highly controversial. We sought to explain this controversy through a historical analysis of transmission research in other diseases. For most of human history, the dominant paradigm was that many diseases were carried by the air, often over long distances and in a phantasmagorical way. This miasmatic paradigm was challenged in the mid to late 19th century with the rise of germ theory, and as diseases such as cholera, puerperal fever, and malaria were found to actually transmit in other ways. Motivated by his views on the importance of contact/droplet infection, and the resistance he encountered from the remaining influence of miasma theory, prominent public health official Charles Chapin in 1910 helped initiate a successful paradigm shift, deeming airborne transmission most unlikely. This new paradigm became dominant. However, the lack of understanding of aerosols led to systematic errors in the interpretation of research evidence on transmission pathways. For the next five decades, airborne transmission was considered of negligible or minor importance for all major respiratory diseases, until a demonstration of airborne transmission of tuberculosis (which had been mistakenly thought to be transmitted by droplets) in 1962. The contact/droplet paradigm remained dominant, and only a few diseases were widely accepted as airborne before COVID-19: those that were clearly transmitted to people not in the same room. The acceleration of interdisciplinary research inspired by the COVID-19 pandemic has shown that airborne transmission is a major mode of transmission for this disease, and is likely to be significant for many respiratory infectious diseases.
Subject(s)
Air Pollution, Indoor , COVID-19 , Humans , Pandemics , Respiratory Aerosols and Droplets , SARS-CoV-2ABSTRACT
Owing to the outbreak of COVID-19, researchers are exploring methods to prevent contact and non-contact infections that occur via multiple transmission routes. However, studies on pre-venting infections caused by droplet transmission in public transportation are insufficient. To prevent the spread of infectious diseases, a new ventilation system in railway vehicles must be devel-oped. In this study, a novel vertical drop airflow (VDA) system is proposed to mitigate the effect of droplet transmission in a high-speed train cabin. The droplet transmission route and droplet fate are investigated using three-dimensional fluid dynamics simulations, performed employing the Eu-lerian–Lagrangian model. Additionally, a porous model is adopted to simulate the effect of close-fitting masks. The results indicate that 120 s after coughing, the decrease in the droplet number in the VDA system is 72.1% of that observed in the conventional system. Moreover, the VDA system effectively suppresses droplet transmission because the maximum droplet travel distances of the VDA systems are 49.9% to 67.0% of those of the conventional systems. Furthermore, the effect of reducing droplet transmission by wearing a close-fitting mask is confirmed in all systems. Thus, the decrease in both droplet number and droplet transmission area in train cabins validate that the proposed VDA system has an effective airflow design to prevent droplet infection. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.
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Smart classrooms are a relatively confined public space for college students. SARS-COV-2 and other respiratory viruses have been shown to pose a more significant threat to human health in relatively confined spaces. Using numerical simulation method to simulate the transmission and concentration distribution of virus-carrying droplets in smart classrooms in three different seasons (summer, winter, transitional seasons: spring and autumn). The Realizable k-ε model is used to simulate the airflow pattern in the smart classroom, and the Lagrangian method is used to simulate the transmission of droplets. The transmission process of droplets produced from the teacher standing on the platform and the student sitting on the seat is studied. The influence of three kinds of outdoor temperature on droplet transmission and the body deposition fraction of people in the smart classroom is analyzed. The results show that droplet transmission speed is maximum at the temperature of 5 degrees when the outdoor temperature is 5 °C, 20 °C, and 35 °C respectively. At 10 s, the transmission distance of droplets increases by 9.55% compared with that at 20 °C and 10.31% compared with that at 35 °C. In addition, the body deposition fraction is also affected by the location of the vent, with downwind contact being 6 times more likely than upwind contact. The research results can provide suggestions and measures for epidemic prevention and control in smart classrooms.
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In the last two years, the world has been overwhelmed by SARS-CoV-2. One of the most important ways to prevent the spread of the virus is the control of indoor conditions: from surface hygiene to ventilation. Regarding the indoor environments, monitoring the presence of the virus in the indoor air seems to be promising, since there is strong evidence that airborne transmission through infected droplets and aerosols is its dominant transmission route. So far, few studies report the successful detection of SARS-CoV-2 in the air; moreover, the lack of a standard guideline for air monitoring reduces the uniformity of the results and their usefulness in the management of the risk of virus transmission. In this work, starting from a critical analysis of the existing standards and guidelines for indoor air quality, we define a strategy to set-up indoor air sampling plans for the detection of SARS-CoV-2. The strategy is then tested through a case study conducted in two kindergartens in the metropolitan city of Milan, in Italy, involving a total of 290 children and 47 teachers from 19 classrooms. The results proved its completeness, effectiveness, and suitability as a key tool in the airborne SARS-CoV-2 infection risk management process. Future research directions are then identified and discussed.
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Air Pollution, Indoor , COVID-19 , Aerosols , Air Pollution, Indoor/prevention & control , COVID-19/diagnosis , Child , Humans , SARS-CoV-2 , VentilationABSTRACT
BACKGROUND: Various forms of noninvasive respiratory support methods are used in the treatment of hypoxemic CO-VID-19 patients, but limited data are available about the corresponding respiratory droplet dispersion. OBJECTIVES: The aim of this study was to estimate the potential spread of infectious diseases for a broad selection of oxygen and respiratory support methods by revealing the therapy-induced aerodynamics and respiratory droplet dispersion. METHODS: The exhaled air-smoke plume from a 3D-printed upper airway geometry was visualized by recording light reflection during simulated spontaneous breathing, standard oxygen mask application, nasal high-flow therapy (NHFT), continuous positive airway pressure (CPAP), and bilevel positive airway pressure (BiPAP). The dispersion of 100 µm particles was estimated from the initial velocity of exhaled air and the theoretical terminal velocity. RESULTS: Estimated droplet dispersion was 16 cm for unassisted breathing, 10 cm for Venturi masks, 13 cm for the nebulizer, and 14 cm for the nonrebreathing mask. Estimated droplet spread increased up to 34 cm in NHFT, 57 cm in BiPAP, and 69 cm in CPAP. A nonsurgical face mask over the NHFT interface reduced estimated droplet dispersion. CONCLUSIONS: During NHFT and CPAP/BiPAP with vented masks, extensive jets with relatively high jet velocities were observed, indicating increased droplet spread and an increased risk of droplet-driven virus transmission. For the Venturi masks, a nonrebreathing mask, and a nebulizer, estimated jet velocities are comparable to unassisted breathing. Aerosols are transported unboundedly in all these unfiltered therapies. The adequate use of protective measures is of vital importance when using noninvasive unfiltered therapies in infectious respiratory diseases.
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Air Movements , Exhalation , Models, Biological , Noninvasive Ventilation , Respiratory Aerosols and Droplets , HumansABSTRACT
INTRODUCTION: The impact of the COVID-19 pandemic on the incidence of notifiable infectious diseases (NIDs) in Taiwan remains unclear. MATERIALS AND METHODS: The number of cases of NID (n = 42) between January and September 2019 and 2020 were obtained from the open database from Taiwan Centers for Disease Control. RESULTS: The number of NID cases was 21,895 between January and September 2020, which was lower than the number of cases during the same period in 2019 (n = 24,469), with a decline in incidence from 102.9 to 91.7 per 100,000 people in 2019 and 2020, respectively. Fourteen airborne/droplet, 11 fecal-oral, seven vector-borne, and four direct-contact transmitted NID had an overall reduction of 2700 (-28.1%), 156 (-23.0%), 557 (-54.8%), and 73 (-45.9%) cases, respectively, from 2019 to 2020. Similar trends were observed for the changes in incidence, which were 11.5 (-28.4%), 6.7 (-23.4%), 2.4 (-55.0%), and 0.3 (-46.2%) per 100,000 people for airborne/droplet, fecal-oral, vector-borne, and direct-contact transmitted NID, respectively. In addition, all the 38 imported NID showed a reduction of 632 (-73.5%) cases from 2019 to 2020. In contrast, 4 sexually transmitted diseases (STDs) showed an increase of 903 (+7.2%) cases from 2019 to 2020, which was attributed to the increase in gonorrhea (from 3220 to 5028). The overall incidence of STDs increased from 52.5 to 56.0 per 100,000 people, with a percentage change of +6.7%. CONCLUSION: This study demonstrated a collateral benefit of COVID-19 prevention measures for various infectious diseases, except STDs, in Taiwan, during the COVID-19 epidemic.