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1.
Asian Journal of Medical Sciences ; 13(12):11-16, 2022.
Article in English | Academic Search Complete | ID: covidwho-2198402

ABSTRACT

Background: Social distancing, mask, and sanitizers are advised to cut the chain of transmission of the droplet and airborne infection since the first case of COVID-19 was reported from Wuhan. Universal mask usage is advised by the center for disease control. Despite this, it is assumed that there is no adequate mask practice. Aims and Objectives: The objectives of the study are as follows: (1) To assess the knowledge and practice regarding optimal mask usage in a different setting by the general community. (2) To identify the barriers for optimal mask usage as experienced by users. Materials and Methods: We did a cross-sectional study in Kerala using self-made validated questionnaire translated to Malayalam, the regional language distributed by web based Google form. The sample size was calculated as 200 with an assumption of awareness regarding mask usage among the general public to be at least 60% with a confidence interval of 95 and allowable error of 10% Knowledge was considered as high if 80–100%, moderate if 60–79% and low if 0–59%. The practice was considered as good if >75, 74–50 satisfactory and if <50, it is termed as unsatisfactory. Results: Overall knowledge regarding masks and their usage was 52. 88% which is low. Only 38% were doing satisfactory practice. There were lacunae in knowledge regarding mask reusage (39.9%), ideal masks in hospital settings (43.3%). Only 26.4% practiced optimal method of mask removal and 38.4% safe mask disposal. Major barriers for mask usage were suffocation (49.3%) and exertional dyspnea (46.9%). Conclusion: More awareness needs to be created among the public for COVID appropriate behavior with a focus on mask usage. There is a need to address the commonly observed barriers for adhering to mask practice. [ FROM AUTHOR]

2.
Journal of Physics: Conference Series ; 2385(1):012094, 2022.
Article in English | ProQuest Central | ID: covidwho-2187977

ABSTRACT

The airborne transmission of the COVID-19 virus was considered the main cause of infection. The increasing concern about the virus spread in confined spaces, characterized by high crowding indexes and an often-inadequate air exchange system, pushes the scientific community to the design of many studies aimed at improving indoor air quality. The risk of transmission depends on several factors such as droplet properties, virus characteristics, and indoor airflow patterns. The main transmission route of the SARS-CoV-2 virus to humans is the respiratory route through small (<100 μm) and large droplets. In an indoor environment, the air exchange plays a fundamental role on the dispersion of the droplets. In this study, an integrated approach was developed to evaluate the influence of the ventilation strategy on the dispersion of respiratory droplets emitted inside a coach bus. There are no specific guidelines and standards on the air exchange rate (AER) values to be respected in indoor environments such as coach buses. The aim of this work is to analyse the influence of ventilation strategy on the respiratory droplet concentration and distribution emitted in a coach bus. Ansys FLUENT was used to numerically solve the well-known transient Navier-Stokes equations (URANS equations), the energy equation and using the Lagrangian Discrete Phase Model (DPM) approach to construct the droplet trajectories. The geometry is representative of an intercity bus, a vehicle constructed exclusively for the carriage of seated passengers. The 3D CAD model represented a coach bus with an HVAC system, within which an infected subject was present. The positions of exhaust vents and air-conditioning vents were chosen to ensure complete air circulation throughout the bus. The infected subject emitted droplets with a well-defined size distribution and mass through the mouth. The air exchange is provided in two different ways: general ventilation (from air intakes positioned along the bus windows and top side of central corridor) and personal ventilation (with air intakes for each passenger). For the general ventilation a single AER value was set (0.3 m3 s−1). The first results obtained showed a slight particle dispersion in the computational domain due to the airflow rate entered through the HVAC system, but a still elevated level of particle concentration tended to accumulate on the area near to infected subject. Additional analysis was executed to evaluate the beneficial effects linked to further addition of airflow through personal air-conditioning vents placed above every passenger's head. The results show the importance of the use of the ventilation system inside a coach bus, highlighting how the contribution linked to of the personal air exchange rate can lead to a significant reduction of droplet concentration exposure and consequently a reduction of the risk of infection from airborne diseases.

3.
American Review of Canadian Studies ; 52(4):502-503, 2022.
Article in English | Academic Search Complete | ID: covidwho-2186944

ABSTRACT

Duffin estimates that 55 vaccines were in development and some, such as the mRNA vaccines developed by Pfizer-BioNTech and Moderna, were entirely novel. These are minor quibbles since Duffin works to her strengths as an historian and maintains a clear focus on the science, medicine, and public health responses to COVID-19. Duffin then turns to the science and medicine of COVID, including topics like testing, treatments, and the development of vaccines. [Extracted from the article]

4.
Building and Environment ; 228:109924, 2023.
Article in English | ScienceDirect | ID: covidwho-2158543

ABSTRACT

Predictive models for airborne infection risk have been extensively used during the pandemic, but there is yet still no consensus on a common approach, which may create misinterpretation of results among public health experts and engineers designing building ventilation. In this study we applied the latest data on viral load, aerosol droplet sizes and removal mechanisms to improve the Wells Riley model by introducing the following novelties i) a new model to calculate the total volume of respiratory fluid exhaled per unit time ii) developing a novel viral dose-based generation rate model for dehydrated droplets after expiration iii) deriving a novel quanta-RNA relationship for various strains of SARS-CoV-2 iv) proposing a method to account for the incomplete mixing conditions. These new approaches considerably changed previous estimates and allowed to determine more accurate average quanta emission rates including omicron variant. These quanta values for the original strain of 0.13 and 3.8 quanta/h for breathing and speaking and the virus variant multipliers may be used for simple hand calculations of probability of infection or with developed model operating with six size ranges of aerosol droplets to calculate the effect of ventilation and other removal mechanisms. The model developed is made available as an open-source tool.

5.
Medical Journal of Malaysia ; 77(Supplement 4):52, 2022.
Article in English | EMBASE | ID: covidwho-2147352

ABSTRACT

Introduction: Ventilation system serves as one of the methods for infection control within patient treatment areas amongst patients and staff. The High infectivity in confined areas raised concerns for patients and staff safety especially during the COVID-19 pandemic. Objective(s): To describe the ventilation system design approach applied in patient areas of a public hospital. Material(s) and Method(s): Four (4) patient-related areas in a 76 bed non-specialist hospital was assessed. The variables included are the airflow, supply air, return air and air filtration. Result(s) and Conclusion(s): The airborne infection isolation room has air flow from the staff area to the patient area. The air inlet provides 100% non-circulating fresh air with 12 air change rate per hour (ACH) located at entrance. The outlet is located on the lower left side of the patient's head. High-efficiency particulate air (HEPA) filter placed at the outlet with negative room pressure. The air conditioned multi bed area has air inlet at the entry point and outlet located farther away from patients and staff. While, the clinical examination room air inlet was placed near the staff area and outlet above the patient treatment area. Both the common multi-bed inpatient and clinical examination rooms have normal pressure. The ventilation system is served from central Air Handling Unit (AHU) and recirculated, however, MERV 13 grade filter is employed as recommended by American Standard Heating and Refrigeration Engineer (ASHRAE) in both multi-bed inpatient area and clinical examination room. Finally, the operation room was provided with laminar air flow from above the patient towards the lower four corners of the room. The room pressure would be relatively positive compared to the surrounding rooms. The HEPA filter is placed at the inlet. The ventilation system design approach in the public hospital assessed caters for airborne-related infectious diseases control. However, further assessment of its effectiveness is required particularly in the operation theater where the room pressure is relatively positive.

6.
Int J Environ Res Public Health ; 19(21)2022 Nov 06.
Article in English | MEDLINE | ID: covidwho-2099555

ABSTRACT

The COVID-19 pandemic has generated a renewed interest in indoor air quality to limit viral spread. In the case of educational spaces, due to the high concentration of people and the fact that most of the existing buildings do not have any mechanical ventilation system, the different administrations have established natural ventilation protocols to guarantee an air quality that reduces risk of contagion by the SARS-CoV-2 virus after the return to the classrooms. Many of the initial protocols established a ventilation pattern that opted for continuous or intermittent ventilation to varying degrees of intensity. This study, carried out on a university campus in Spain, analyses the performance of natural ventilation activated through the information provided by monitoring and visualisation of real-time data. In order to carry out this analysis, a experiment was set up where a preliminary study of ventilation without providing information to the users was carried out, which was then compared with the result of providing live feedback to the occupants of two classrooms and an administration office in different periods of 2020, 2021 and 2022. In the administration office, a CO2-concentration-based method was applied retrospectively to assess the risk of airborne infection. This experience has served as a basis to establish a route for user-informed improvement of air quality in educational spaces in general through low-cost systems that allow a rational use of natural ventilation while helping maintain an adequate compromise between IAQ, comfort and energy consumption, without having to resort to mechanical ventilation systems.


Subject(s)
Air Pollution, Indoor , COVID-19 , Humans , COVID-19/epidemiology , Spain/epidemiology , Pandemics , Retrospective Studies , SARS-CoV-2 , Ventilation/methods , Air Pollution, Indoor/analysis
7.
37th International Technical Conference on Circuits/Systems, Computers and Communications, ITC-CSCC 2022 ; : 514-517, 2022.
Article in English | Scopus | ID: covidwho-2097628

ABSTRACT

Article presents the development of the Airborne Infection Isolation Room (AIIR) thermal environmental control system. To support Covid-19 patients in the Airborne Infection Isolation Room (AIIR) Betong Hospital. The parameters to be controlled are according to the CDC and ASHRAE standard. Air pressure in the Isolation room <-mathbf{2}.mathbf{5}mathbf{Pa} Air Temperature Relative Humidity and Air Chang Rate are 21-24°C, 40-60%RH and 12 ACH respectively [1], [2]. The dehumidification system is a Desiccant wheel (DW) with diameters of 60 cm containing 3 kg of silica gel. The result of the measurement experimental in AIIR found that negative pressure-6.5 Pa average temperature relative humidity and air changes rate is 37.78°C 48.06 %RH and 16.57 ACH respectively. © 2022 IEEE.

8.
J Occup Environ Hyg ; : 1-20, 2022 Oct 18.
Article in English | MEDLINE | ID: covidwho-2077491

ABSTRACT

In emergencies like the COVID-19 pandemic, reuse or reprocessing of filtering facepiece respirators (FFRs) may be required to mitigate exposure risk. Research gap: Only a few studies evaluated decontamination effectiveness against SARS-CoV-2 that are practical for low-resource settings. This study aimed to determine the effectiveness of a relatively inexpensive ultraviolet germicidal irradiation chamber to decontaminate FFRs contaminated with SARS-CoV-2. A custom design UVGI chamber was constructed to determine the ability to decontaminate seven FFR models including N95s, KN95 and FFP2s inoculated with SARS-CoV-2. Vflex was excluded due to design folds/pleats and UVGI shadowing inside the chamber. Structural and functional integrity tolerated by each FFR model on repeated decontamination cycles was assessed. Twenty-seven participants were fit tested over 30 cycles for each model and passed if the fit factor was ≥100. Of the FFR models included for testing, only the KN95 model failed filtration. The 3M™ 3M 1860 and Halyard™ duckbill 46727 (formerly Kimberly Clark) models performed better on fit testing than other models for both pre-and-post decontaminations. Fewer participants (0.3 and 0.7%, respectively) passed fit testing for Makrite 9500 N95 and Greenline 5200 FFP2 and only two for the KN95 model post decontamination. Fit testing appeared to be more affected by donning & doffing, as some passed with adjustment and repeat fit testing. A ≥ 3 log reduction of SARS-CoV-2 was achieved for worn-in FFRs namely Greenline 5200 FFP2. Conclusion: The study showed that not all FFRs tested could withstand 30 cycles of UVGI decontamination without diminishing filtration efficiency or facial fit. In addition, SARS-CoV-2 log reduction varied across the FFRs, implying that the decontamination efficacy largely depends on the decontamination protocol and selection of FFRs. We demonstrated the effectiveness of a low-cost and scalable decontamination method for SARS-CoV-2 and the effect on fit testing using people instead of manikins. It is recognised that extensive experimental evidence for the reuse of decontaminated FFRs is lacking, and thus this study would be relevant and of interest in crisis-capacity settings, particularly in low-resource facilities.

9.
Toxics ; 10(10)2022 Sep 30.
Article in English | MEDLINE | ID: covidwho-2066491

ABSTRACT

Mass COVID-19 infection cases in indoor spaces have been continuously reported since its global outbreak, generating increasing public interest in reducing the spread of the virus. This study considered a situation in which an infected individual continuously releases the virus into the air in a classroom, simulated by continuous injection of NaCl particles ≤ 5 µm, with heater operation during winter. The effects of applying natural ventilation and operating one or two air purifiers on the removal of virus-containing aerosols were experimentally compared and analyzed based on the spatiotemporal changes in NaCl concentration within the classroom. When a heater was operated with all windows shut, operating one and two air purifiers reduced the amount of the aerosol in indoor air by approximately 50 and 60%, respectively, compared to the case with no air purifier. Additionally, when the heater was operated with one or two air purifiers under natural ventilation, the amount of virus-containing aerosol in the air was reduced by 86-88% compared to the case with neither natural ventilation nor air purifier. Because natural ventilation significantly varies with weather conditions and particulate matter concentrations, combining natural ventilation with air purifiers in classrooms during winter needs to be adjusted appropriately.

10.
J Hosp Infect ; 129: 17-21, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2049479

ABSTRACT

BACKGROUND: Despite multifactorial evidence, the safe and effective elimination of free-floating micro-organisms remains a significant scientific challenge. ZeBox Technology exploits microbial Zeta Potential, to extract and eliminate them from free-flowing air, using a non-ionizing electric field, in combination with a microbicidal surface. AIM: Evaluation of ZeBox Technology against aerosolized SARS-CoV-2 and Mycobacterium tuberculosis under controlled conditions. METHODS: SARS-CoV-2 and M. tuberculosis H37Ra were used in this study. Individual micro-organisms were aerosolized using a Collison nebulizer inside an air-sealed test chamber. Air samples were collected from the chamber on to a Mixed Cellulose Ester membrane, at various time points, and used for enumeration. SARS-CoV-2 was enumerated using qRT-PCR, while M. tuberculosis H37Ra was quantified using standard microbiological procedures. FINDINGS: We established a viable aerosolized microbial load of ∼10E9 and ∼10E6 for SARS-CoV-2 and M. tuberculosis H37Ra, respectively, inside the test chamber. Under ideal conditions, the floating microbial load was at a steady-state level of 10E9 for SARS-CoV-2 and 10E6 for M. tuberculosis. When the ZeBox-Technology-enabled device was operated, the microbial load reduced significantly. A reduction of ∼10E4.7 was observed for M. tuberculosis, while a reduction of ∼10E7 for SARS-CoV-2 was observed within a short duration. The reduction in airborne SARS-CoV-2 load was qualitatively and quantitatively measured using fluorescence analysis and qRT-PCR methods, respectively. CONCLUSION: This validation demonstrates the efficacy of the developed technology against two of the deadliest micro-organisms that claim millions of lives worldwide. In conjunction with the existing reports, the present validation proved the true broad-spectrum elimination capability of ZeBox technology.


Subject(s)
COVID-19 , Mycobacterium tuberculosis , Tuberculosis , Humans , SARS-CoV-2 , Mycobacterium tuberculosis/genetics , COVID-19/prevention & control , Tuberculosis/prevention & control , Technology
11.
Osmaniye Korkut Ata Universitesi Fen Bilimleri Enstitusu Dergisi / Osmaniye Korkut Ata University Journal of Natural and Applied Sciences ; 5(2):1041-1052, 2022.
Article in English | GIM | ID: covidwho-2026789

ABSTRACT

Covid-19 SARS-CoV-2 (severe acute respiratory syndrome-coronavirus-2) is a new type of coronavirus known as an infectious upper respiratory tract infection disease. The coronavirus, which poses a great threat to human health worldwide, emerged in Wuhan, China in December 2019. The most important reason for coronavirus epidemics to become a pandemic that the disease was easily transmitted by droplets in close proximity with infected people. The disease spread rapidly all over the world within a few months and it was declared a worldwide epidemic by the World Health Organization in March 2020. It poses a risk for severe diseases such as hypertension, diabetes, cardiovascular disease, cancer, chronic lung disease and chronic kidney disease in the advanced age group. Considering the mortality rates to date, great efforts have been made both worldwide and in our country to manufacture successful drugs and vaccines against Covid-19 infection. The main purpose of this review is to assist in an immune response and preventive work for Covid-19, thanks to the available information about the coronavirus epidemic that deeply affects humanity and the diseases it causes.

12.
Clin Infect Dis ; 2021 Sep 14.
Article in English | MEDLINE | ID: covidwho-2017760

ABSTRACT

BACKGROUND: SARS-CoV-2 epidemiology implicates airborne transmission; aerosol infectiousness and impacts of masks and variants on aerosol shedding are not well understood. METHODS: We recruited COVID-19 cases to give blood, saliva, mid-turbinate and fomite (phone) swabs, and 30-minute breath samples while vocalizing into a Gesundheit-II, with and without masks at up to two visits two days apart. We quantified and sequenced viral RNA, cultured virus, and assayed sera for anti-spike and anti-receptor binding domain antibodies. RESULTS: We enrolled 49 seronegative cases (mean days post onset 3.8 ±2.1), May 2020 through April 2021. We detected SARS-CoV-2 RNA in 45% of fine (≤5 µm), 31% of coarse (>5 µm) aerosols, and 65% of fomite samples overall and in all samples from four alpha-variant cases. Masks reduced viral RNA by 48% (95% confidence interval [CI], 3 to 72%) in fine and by 77% (95% CI, 51 to 89%) in coarse aerosols; cloth and surgical masks were not significantly different. The alpha variant was associated with a 43-fold (95% CI, 6.6 to 280-fold) increase in fine aerosol viral RNA, compared with earlier viruses, that remained a significant 18-fold (95% CI, 3.4 to 92-fold) increase adjusting for viral RNA in saliva, swabs, and other potential confounders. Two fine aerosol samples, collected while participants wore masks, were culture-positive. CONCLUSION: SARS-CoV-2 is evolving toward more efficient aerosol generation and loose-fitting masks provide significant but only modest source control. Therefore, until vaccination rates are very high, continued layered controls and tight-fitting masks and respirators will be necessary.

13.
IOP Conference Series. Earth and Environmental Science ; 1056(1):012001, 2022.
Article in English | ProQuest Central | ID: covidwho-2017609

ABSTRACT

Our world is resisting the new pandemic “severe acute respiratory syndrome Coronavirus 2” (SARS-CoV-2) causing the disease known as COVID-19. To date, more than two hundred and three million cases were confirmed out of who more than four million died. Sharing data that will help the community to intervene with measures that will decrease the spread of the virus and protect the population is an obligation. This will help the world cope with this pandemic. This research aims to highlight the different criteria that will determine that the building of a health facility is ready to control the infection of this virus and similar airborne viruses. The research developed an evaluation tool that can be used by hospital administration to assess the hospital building readiness to prevent and control airborne infection from the viewpoint of architecture if it is an existing one or alternatively it can assess the design in case of a new hospital building, determining required roles and responsibilities.

14.
Cureus ; 14(5): e25258, 2022 May.
Article in English | MEDLINE | ID: covidwho-2006481

ABSTRACT

BACKGROUND: Dilution ventilation by enhancing fresh air intake has been prescribed to reduce airborne infection spread during the COVID-19 pandemic. This is all the more important in assembly spaces like auditoriums. Premier technology institutes have large campuses with large auditoriums for academic and cultural events in India. These institutes serve as role models for society, where gatherings are essential, but there is also the possibility of transmission of all airborne respiratory infections, including tuberculosis, into the community. The fresh air taken in should also be filtered for pollution to prevent other lung issues. AIMS: Fresh air intake and filtration have been studied in order to understand whether the outside air supplied indoors is filtered for PM2.5, which is a major ambient polluter in India. Settings and design/methods: In this study, the Right to Information Act of 2005 has been used to obtain first-hand information from the institutes with respect to the heating, ventilation, and air conditioning (HVAC) systems in their auditoriums. Twelve of the 19 institutes fall in cities with non-attainment of ambient air quality standards. RESULTS: Eleven out of all those had recently integrated fresh air supply, and six replied in the negative. Only one out of all of them had appropriate filters. CONCLUSION: This study highlights the need for a possible trade-off between the use of air conditioners for thermal comfort + assumed protection against PM2.5, which is the switching off of air conditioners and manually opening up windows and using fans for ventilation. Indian HVAC design for gathering spaces, especially educational institutes, needs to factor in fresh air for dilution ventilation as well as PM2.5 filtration.

15.
Build Environ ; 224: 109530, 2022 Oct.
Article in English | MEDLINE | ID: covidwho-2003904

ABSTRACT

This study used Computational Fluid Dynamics (CFD) to investigate air disinfection for SARS-CoV-2 by the Upper-Room Germicidal Ultraviolet (UR-GUV), with focus on ceiling impact. The study includes three indoor settings, i.e., low (airport bus), medium (classroom) and high (rehearsal room) ceilings, which were ventilated with 100% clean air (CA case), 80% air-recirculation with a low filtration (LF case), and 80% air-recirculation with a high filtration (HF case). According to the results, using UR-GUV can offset the increased infection risk caused by air recirculation, with viral concentrations in near field (NF) and far field (FF) in the LF case similar to those in the CA case. In the CA case, fraction remaining (FR) was 0.48-0.73 with 25% occupancy rate (OR) and 0.49-0.91 with 45% OR in the bus, 0.41 in NF and 0.11 in FF in the classroom, and 0.18 in NF and 0.09 in FF in the rehearsal room. Obviously, UR-GUV performance in NF can be improved in a room with a high ceiling where FR has a power relationship with UV zone height. As using UR-GUV can only extend the exposure time to get infection risk of 1% (T 1% ) to 8 min in NF in the classroom, and 47 min in NF in the rehearsal room, it is necessary to abide by social distancing in the two rooms. In addition, T 1% in FF was calculated to be 18.3 min with 25% OR and 21.4% with 45% OR in the airport bus, showing the necessity to further wear a mask.

16.
Journal of General Internal Medicine ; 37:S438-S439, 2022.
Article in English | EMBASE | ID: covidwho-1995585

ABSTRACT

CASE: A 83-year-old male with a history of non-insulin dependent diabetes mellitus, and coronary artery disease presented with four days of worsening myalgias, subjective fevers, and abdominal distention. He had no history of abdominal surgery, sick contacts or medication changes. He had a temperature of 99.2°F, a heart rate of 80 beats per minute, a respiratory rate of 18 breaths per minute, a blood pressure of 105/80 mmHg, and an oxygen saturation of 96% on room air. On examination, the abdomen was distended but without tenderness or guarding. Abdomen Computed Tomography (CT) scan revealed pancolonic severe gaseous dilatation with no transition point. COVID 19 polymerase chain reaction was noted to be positive, along with an elevated D-dimer of 2.58, ESR of 60 mm/h and CRP 40 mg/l;otherwise the laboratory workup including a respiratory and gastrointestinal panel, blood and sputum culture were negative. Following multidisciplinary and shared decisionmaking, a rectal tube was placed and the patient was given neostigmine with resolution of symptoms and subsequent radiographic demonstration of improvement in the colonic distention within 48 hours. Unfortunately, the patient suffered a cardiac arrest on day 5 of his hospitalization and per the family's request, aggressive treatment was aborted in favor of comfort measures. IMPACT/DISCUSSION: While COVID-19 is primarily an airborne infection, widespread expression of its receptor, Angiotensin Converting Enzyme type 2 (ACE2), throughout the gastrointestinal (GI) tract causes GI tract-related clinical symptoms in the absence of respiratory symptoms, leading to a delay in COVID-19 infection diagnosis. While anorexia (50.2%) and diarrhea (49.5%) are the most common gastrointestinal symptoms of COVID 19, our patient presented with abdominal discomfort (2%). Acute colonic pseudo-obstruction or Ogilvie syndrome is a functional disorder characterized by profound dilatation of the colon without a true mechanical obstruction. An association between certain viral infections (Herpes) and intestinal pseudo-obstruction has been demonstrated previously. The mechanism of such a development is hypothesized to be due to the viral invasion of the myenteric plexus. Similarly, COVID-19 has demonstrated neurotropic potential leading to the development of Ogilvie syndrome. Treatment modalities available for the treatment include bowel rest, nasogastric and rectal tube placement, electrolyte correction, neostigmine and possible endoscopic/surgical intervention with a preferably good prognosis. CONCLUSION: 1. The full range of effects of the COVID 19 virus are yet to be discovered. Loss of parasympathetic spinal control of bowel motility may be one possible manifestation of this disease. 2. Gastrointestinal sequelae of COVID 19 respond well to conservative management and should warrant a low threshold for the investigation and implementation of such treatment.

17.
Japan Medical Journal ; - (5125):30-40, 2022.
Article in Japanese | Ichushi | ID: covidwho-1995239
18.
ASHRAE Transactions ; 127:246-253, 2021.
Article in English | ProQuest Central | ID: covidwho-1980710

ABSTRACT

The purpose of a ventilation system for indoor spaces is to create a safe environment for the occupants by diluting the concentration levels of hazardous contaminants and to minimize the risk of infection due to spread of airborne pathogens. The effectiveness of ventilation system depends on several inter related factors including the supply airflow rate, number and locations of supply diffusers, and number and locations of return grilles. With the help of Computational Fluid Dynamics (CFD) analyses, this study systematically evaluates the impact of three different HVAC configurations on the airflow patterns, distribution of contaminant, and the risk of infection in a small office space with two cubicles. The HVAC configuration with a single supply and a single return can create adverse airflow patterns which can promote spread of contaminants and increase the risk of infection farther from the source. When an additional supply diffuser is introduced with the same single return, the zone of high risk of infection remained in the vicinity of the source. However, the overall risk of infection in the space remained the same. Addition of another return created aerodynamic containment zones in the space which provided easy path for the contaminated air to leave the space and reduced the overall risk of infection. Since the location of an infected individual is not known a priori, the aerodynamic containment with distributed supply and distributed return can be the best strategy for reducing the probability of infection in indoor spaces. These studies demonstrate that CFD analyses can help in identifying the potential risk of high infection due to poor airflow distribution into a space and can provide valuable insights for developing appropriate mitigation strategies to create safe indoor environment.

19.
ASHRAE Transactions ; 127:174-184, 2021.
Article in English | ProQuest Central | ID: covidwho-1980303

ABSTRACT

Thirty years of evidence supports the efficacy of ultra-clean air in preventing surgical site infection (SSI). Ultraclean is defined as fewer than 10 Colony Forming Units (CFUs) per cubic meter or <10CFU/m3 (35ft3) However, achieving and maintaining ultraclean conditions in the contemporary operating room has proven challenging. For decades, Laminar Air Flow (LAF) systems were recommended for use in rooms where infection sensitive joint arthroplasty procedures are performed. But, a growing body of evidence has called the efficacy of LAF in prevention of these infections into question. As a result, CD C no longer recommends use of LAF for joint arthroplasty. The WHO has gone a step further issuing a conditional recommendation against its use in these procedures. At the same time, demand for total hip and knee arthroplasties are expected to grow exponentially over the next decade and for reasons that are unclear rates of prosthetic joint infection (PJI) are on the rise. Taken together, these factors suggest that the time has come to rethink management of airborne contamination and ventilation technology in the operating room. Temperature-controlled Air Flow (TcAF) is a novel ventilation technology that has been proven to maintain ultra-clean conditions throughout the entire operating room. TcAF uses continuous HEPA filtration and combines a robust central unidirectional down-flow driven by gravity from a temperature gradient together with mixing ventilation in the periphery of the room. While TcAF has been scientifically validated to maintain ultra-clean conditions of <10CFU/m3(35ft3) throughout the entire operating room, the impact of TcAF on prevention of surgical site infection was unknown. The aim of this study was to evaluate the efficacy of TcAF on prosthetic joint infection (PJI). A retrospective case control study was performed with 1,000 consecutive cases of primary total joint arthroplasty before and 1,000 consecutive cases after the installation of an ultra-clean TcAF system. TcAF was associated with a statistically significant reduction in surgical site infection. With reduction in surgical site infection proving to be ever more challenging and demand for infection sensitive procedures rising, more rigorous attention to airborne contamination may represent a new pathway to improvement. While not the focus of this paper, the advent of Covid-19 should bring into greater focus the risk of airborne transmission andfurther incentiviņe mitigation.

20.
Build Environ ; 222: 109440, 2022 Aug 15.
Article in English | MEDLINE | ID: covidwho-1965601

ABSTRACT

Air distribution is an effective engineering measure to fight against respiratory infectious diseases like COVID-19. Ventilation indices are widely used to indicate the airborne infection risk of respiratory infectious diseases due to the practical convenience. This study investigates the relationships between the ventilation indices and airborne infection risk to suggest the proper ventilation indices for the evaluation of airborne infection risk control performance of air distribution. Besides the commonly used ventilation indices of the age of air (AoA), air change effectiveness (ACE), and contaminant removal effectiveness (CRE), this study introduces two ventilation indices, i.e., the air utilization effectiveness (AUE) and contaminant dispersion index (CDI). CFD simulations of a hospital ward and a classroom served by different air distributions, including mixing ventilation, displacement ventilation, stratum ventilation and downward ventilation, are validated to calculate the ventilation indices and airborne infection risk. A three-step correlation analysis based on Spearman's rank correlation coefficient, Pearson correlation coefficient, and goodness of fit and a min-max normalization-based error analysis are developed to qualitatively and quantitatively test the validity of ventilation indices respectively. The results recommend the integrated index of AUE and CDI to indicate the overall airborne infection risk, and CDI to indicate the local airborne infection risk respectively regardless of the effects of air distribution, supply airflow rate, infectivity intensity, room configuration and occupant distribution. This study contributes to airborne transmission control of infectious respiratory diseases with air distribution.

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