scholarly journals Displacement ventilation: a viable ventilation strategy for makeshift hospitals and public buildings to contain COVID-19 and other airborne diseases

2020 ◽  
Vol 7 (9) ◽  
pp. 200680
Author(s):  
Rajesh K. Bhagat ◽  
P. F. Linden
Keyword(s):  
Negative Pressure ◽  
Natural Ventilation ◽  
Public Spaces ◽  
Positive Pressure ◽  
Air Conditioner ◽  
Displacement Ventilation ◽  
Link Type ◽  
Building Ventilation ◽  
High Level ◽  
General Wards

The SARS-CoV-2 virus has so far infected more than 31 million people around the world, and its impact is being felt by all. Patients with diseases such as COVID-19 should ideally be treated in negative pressure isolation rooms. However, due to the overwhelming demand for hospital beds, patients have been treated in general wards, hospital corridors and makeshift hospitals. Adequate building ventilation in hospitals and public spaces is a crucial factor to contain the disease (Escombe et al. 2007 PLoS Med. 4 ; Escombe et al. 2019 BMC Infect. Dis. 19 , 88 ( doi:10.1186/s12879-019-3717-9 ); Morawska & Milton 2020 Clin. Infect. Dis . ciaa939. ( doi:10.1093/cid/ciaa939 )), to exit lockdown safely, and reduce the chance of subsequent waves of outbreaks. A recently reported air-conditioner-induced COVID-19 outbreak caused by an asymptomatic patient, in a restaurant in Guangzhou, China (Lu et al. 2020 Emerg. Infect. Dis. 26 ) exposes our vulnerability to future outbreaks linked to ventilation in public spaces. We argue that displacement ventilation (either mechanical or natural ventilation), where air intakes are at low level and extracts are at high level, is a viable alternative to negative pressure isolation rooms, which are often not available on site in hospital wards and makeshift hospitals. Displacement ventilation produces negative pressure at the occupant level, which draws fresh air from outdoors, and positive pressure near the ceiling, which expels the hot and contaminated air out. We acknowledge that, in both developed and developing countries, many modern large structures lack the openings required for natural ventilation. This lack of openings can be supplemented by installing extract fans. We have also discussed and addressed the issue of the ‘lock-up effect’. We provide guidelines for such mechanically assisted, naturally ventilated makeshift hospitals.

scholarly journals Displacement ventilation: a viable ventilation strategy for makeshift hospitals and public buildings to contain Covid-19 and other airborne diseases

2020 ◽  
Author(s):  
Rajesh K. Bhagat ◽  
P. F. Linden
Keyword(s):  
Negative Pressure ◽  
Natural Ventilation ◽  
Public Spaces ◽  
Positive Pressure ◽  
Air Conditioner ◽  
Displacement Ventilation ◽  
Public Buildings ◽  
Building Ventilation ◽  
High Level ◽  
General Wards

AbstractThe SARS-CoV-2 virus has so far infected more than 2.4 million people around the world, and its impact is being felt by all. Patients with airborne diseases such as Covid-19 should ideally be treated in negative pressure isolation rooms. However, due to the overwhelming demand for hospital beds, patients are being treated in general wards, hospital corridors, and makeshift hospitals. Adequate building ventilation in hospitals and public spaces is a crucial factor to contain the disease1,2, to exit the current lockdown situation, and reduce the chance of subsequent waves of outbreaks. Lu et al. 3 reported an air-conditioner induced Covid-19 outbreak, by an asymptomatic patient, in a restaurant in Guangzhou, China, which exposes our vulnerability to future outbreaks linked to ventilation in public spaces. We demonstrate that displacement ventilation (either mechanical or natural ventilation), where air intakes are at low level and extracts are at high level, is a viable alternative to negative pressure isolation rooms, which are often not available on site in hospital wards and makeshift hospitals. Displacement ventilation produces negative pressure at the occupant level, which draws fresh air from outdoor, and positive pressure near the ceiling, which expels the hot and contaminated air out. We acknowledge that, in both developed and developing countries, many modern large structures lack the openings required for natural ventilation. This lack of openings can be supplemented by installing extract fans. We provide guidelines for such mechanically assisted-naturally ventilated makeshift hospitals, and public spaces such as supermarkets and essential public buildings.

On the competition between lateral convection and upward displacement in a multi-zone naturally ventilated space

2012 ◽  
Vol 707 ◽  
pp. 393-404 ◽  
Author(s):  
Andrea S. Kuesters ◽  
Andrew W. Woods
Keyword(s):  
Natural Ventilation ◽  
Shopping Malls ◽  
Energy Usage ◽  
Displacement Ventilation ◽  
Low Level ◽  
Different Temperatures ◽  
Upward Displacement ◽  
Temperature Contrast ◽  
High Level ◽  
Convection Dominated

AbstractWe consider the flow which develops when two separate spaces maintained at different temperatures, both in excess of the exterior temperature, are connected through high and low level openings to a central atrium in which there is negligible heat load but which can naturally ventilate through high and low level openings to the exterior. We show that with a small temperature contrast between the spaces or large openings from the atrium to the exterior, upflow displacement ventilation develops in each of the spaces, with air entering from the atrium at low level and exiting at high level. However, with a larger temperature contrast between the spaces or small openings between the atrium and the exterior, a convective circulation develops between the spaces, with upflow in the warmer space and downflow in the colder space. Exterior air, which may enter the atrium at low level, flows into the warmer space along with the air from the colder space. At high level, air flows back into the atrium from the warmer space, and then either vents from the building or flows into the colder space. In this convection dominated flow regime, the colder space is a net heat sink, whereas with the upward displacement ventilation, this space acts as a net heat source. This can have significant implications for energy usage and on the build up of contaminants in each of the spaces. We also show that in both steady flow regimes, the air at mid-level in the atrium is unventilated and stagnant. We discuss the relevance of our model for controlled natural ventilation in large public buildings such as shopping malls where individual shops often maintain temperatures independently of the central atrium-space.

Study of Toynbee Phenomenon by Combined Intranasopharyngeal and Tympanometric Measurements

1988 ◽  
Vol 97 (2) ◽  
pp. 199-206 ◽  
Author(s):  
Yehuda Finkelstein ◽  
Yuval Zohar ◽  
Yoav P. Talmi ◽  
Nelu Laurian
Keyword(s):  
Middle Ear ◽  
Negative Pressure ◽  
Pressure Change ◽  
Positive Pressure ◽  
New Information ◽  
Pressure Changes ◽  
Rapid Pressure

The Toynbee maneuver, swallowing when the nose is obstructed, leads in most cases to pressure changes in one or both middle ears, resulting in a sensation of fullness. Since first described, many varying and contradictory comments have been reported in the literature concerning the type and amount of pressure changes both in the nasopharynx and in the middle ear. In our study, the pressure changes were determined by catheters placed into the nasopharynx and repeated tympanometric measurements. New information concerning the rapid pressure variations in the nasopharynx and middle ear during deglutition with an obstructed nose was obtained. Typical individual nasopharyngeal pressure change patterns were recorded, ranging from a maximal positive pressure of + 450 to a negative pressure as low as −320 mm H2O.

DETERMINATION AERODYNAMIC CHARACTERISTICS OF ELEMENTS OF BUILDING VENTILATION SYSTEMS IN LABORATORY CONDITIONS

2021 ◽  
Vol 3 (1) ◽  
pp. 049-053
Author(s):  
M. A. KRIVOSHEIN ◽  
◽  
K. D. SMIRNOV ◽  
K. V. MESHKO ◽  
◽  
...  
Keyword(s):  
Natural Ventilation ◽  
Check Valve ◽  
Aerodynamic Characteristics ◽  
Laboratory Conditions ◽  
Building Ventilation ◽  
Ventilation Systems

The article presents the layout and appearance of the stand, developed to determine the aerodynamic characteristics of the elements of ventilation systems. The technique of determining the aerodynamic characteristics of ventilation elements using the developed stand is considered. The results of tests of a check valve used in natural ventilation systems of buildings are presented. The obtained characteristic of the check valve is proposed to be used in calculating and predicting the operation of ventilation systems in buildings in which the check valves under consideration will be installed

Effect of airway wall flexibility on clearance by simulated cough

1987 ◽  
Vol 63 (2) ◽  
pp. 707-712 ◽  
Author(s):  
V. Soland ◽  
G. Brock ◽  
M. King
Keyword(s):  
Negative Pressure ◽  
Rectangular Cross Section ◽  
Dynamic Compression ◽  
Wave Formation ◽  
Bottom Surface ◽  
Positive Pressure ◽  
Airway Wall ◽  
Wall Flexibility ◽  
Mucus Rheology ◽  
The Relationship

In our previous study, we investigated the relationship between mucus rheology, depth of mucus layer, and clearance by simulated cough. The purpose of the present study was to examine the effect of airway wall flexibility on the clearance of mucuslike gels. Transient airflows similar to cough were generated by both positive and negative pressure, the latter to mimic the dynamic compression that occurs during real cough. As in the previous study, the trachea was modeled as a trough of rectangular cross section with only the bottom lined with the mucus simulant. Clearance was followed by observing the displacement of marker particles. Since cough clearance is intimately related to wave formation in the mucus blanket, we hypothesized that clearance might be impeded if the wave formation occurred simultaneously in the wall and its lining layer. Thus, in one set of experiments the bottom rigid surface of the model trachea was replaced with a frame over which a flexible membrane could be drawn, whereas in the other set the rigid top was replaced by the frame. We also examined the effect of negative-pressure cough in excised canine tracheae, comparing the case where the tracheal membrane was free to deform vs. the case where it was secured. For the rigid-walled model, clearance by positive or negative pressure, with matched flow pattern, was the same. With the mucus simulant lining the flexible bottom surface, clearance increased with increasing membrane flexibility for negative-pressure cough and decreased for positive-pressure cough.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of intrathoracic pressure on pressure-volume characteristics of the lung in man

1975 ◽  
Vol 38 (3) ◽  
pp. 411-417 ◽  
Author(s):  
H. S. Goldberg ◽  
W. Mitzner ◽  
K. Adams ◽  
H. Menkes ◽  
S. Lichtenstein ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Total Lung Capacity ◽  
Human Subjects ◽  
Ambient Pressure ◽  
Intrathoracic Pressure ◽  
Dynamic Compliance ◽  
Positive Pressure ◽  
Lung Capacity ◽  
Airway Opening ◽  
Volume Characteristics

Quasi-static pressure-volume (P-V) curves in normal seated human subjects were determined with pressure at the airway opening (Pa0) set below (negative pressure), above (positive pressure), or equal to ambient pressure. Dynamic compliance (Cdyn) during controlled continuous negative pressure breathing (CNPB) was also studied. Quasi-static P-V curves at negative pressure were decreased in slope, reflected a decrease in total lung capacity, and intersected the P-V curve obtained at ambient Pa0. At positive pressure the P-V curves showed an increase in slope and an increase in total lung capacity. During CNPB a fall in Cdyn was found. The fall in Cdyn was rapid and persisted for the duration of CNPB. Cdyn promptly returned to control levels when Pa0 was adjusted to ambient pressure.

scholarly journals ENVIRONMENTAL MANAGEMENT IN THE HINTERLANDS OF NORTHERN SAMAR

2019 ◽  
Vol 7 (3) ◽  
pp. 163-176
Author(s):  
Felisa L. Sanico
Keyword(s):  
Environmental Protection ◽  
Natural Ventilation ◽  
Motor Vehicle ◽  
Positive Response ◽  
White Paper ◽  
Air Conditioner ◽  
Natural Lighting ◽  
Fluorescent Lamps ◽  
Local Water ◽  
And Mathematics

This study investigated the perceptions of the faculty of members, school official and students in terms of environmental protection and management. It employed random sampling using survey questionnaires to gather data from the respondents. Frequency counts and percentage were used to process the data. Most of the respondents had positive responses on waste reduction and management, as the commonly used environmental protection strategy in the school. A majority of them rejected plastics and agreed that these are harmful to the environment friendly products, are materials that can be recycled, and less favored materials are the non-toxic products, and a majority of the respondents favored that individual bulk packaging is preferred than bulk packaging of products from suppliers. High percentage favored that the classrooms are designed to make use of natural ventilation and natural lighting. Most of the respondents had negative responses on the issue of planning the campus in such a way as to reduce the use of motor vehicle in terms of motor boat as mode of transportation. There was a high percentage of positive response regarding the physical greening of the school, as observed in the entire campus. A majority of the respondents had positive responses on fluorescent lamps as the commonly used source of light, than of the use of incandescent. Most of the respondents had negative response on artesian well as the source of water, and a high positive response was observed regarding local water works as the source of water for everyday use.  Majority of the respondents agreed that office machines are turned off when not in use, and using the fans whenever possible also had a high positive response; only fewer respondents agreed on the usage of air conditioner. A majority of the respondents agreed that white paper is the most preferred kind of paper in the school. A majority of the respondents had positive response in using the used paper in photocopying articles as commonly used paper recycling or use of reduction program. A majority of the respondents agreed that composting biodegradable was right in the campus and wet waste sent to recyclers had a low positive response. There was a high percentage of positive response on disposable plastic utensils as the most discouraged material in the canteen. Disposable cups, disposable plates, paper napkins and plastic wrappers had also high percentage as materials discouraged in the canteen. A majority of the respondents agreed that waste segregation in the school is practiced. Most of the respondents agreed that containers for biodegradable and non-biodegradable are provided in the entire campus. A majority of the respondents favored that biodegradable materials are made to compose. Respondents favored that sealing properly before disposal of hazardous/chemicals water is done inside the campus. All the eight (8) environment concerns/themes are integrated in the curriculum. A majority of the respondents indicated that environment concerns/themes are incorporated in Music, Health and Physical Education. They are also integrated in English, Social Studies, Pilipino, and Mathematics.

Simple Device for Producing Continuous Negative Pressure in Infants With IRDS

PEDIATRICS ◽  
1973 ◽  
Vol 52 (1) ◽  
pp. 128-131
Author(s):  
Eduardo Bancalari ◽  
Tilo Gerhardt ◽  
Ellen Monkus
Keyword(s):  
Intensive Care Unit ◽  
Negative Pressure ◽  
Positive Pressure Ventilation ◽  
Newborn Infants ◽  
Transpulmonary Pressure ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure ◽  
School Of Medicine ◽  
Newborn Intensive Care Unit ◽  
Newborn Intensive Care

Increasing experience with the use of continuous transpulmonary pressure, either positive or negative, during the last years has clearly demonstrated the success of this mode of therapy in IRDS.1-3 Forty newborn infants with this disease have been treated with continuous negative pressure (CNP) in the Newborn Intensive Care Unit, Department of Pediatrics, University of Miami School of Medicine, using a modified incubator-respirator.* Twenty-one required only CNP, three of whom died (14%). Among the 19 who needed CNP plus intermittent positive pressure ventilation, nine died (47%). All required more than 70% oxygen to maintain a Pao2 over 50 mm Hg before using CNP.

The Spaces Between Us

2014 ◽  
pp. 237-252
Author(s):  
Mohanalakshmi Rajakumar
Keyword(s):  
Social Media ◽  
Economic Development ◽  
Cultural Differences ◽  
Public Spaces ◽  
Luxury Brands ◽  
Online Forums ◽  
National Population ◽  
The World ◽  
Per Capita ◽  
High Level

Despite having one of the highest per-capita incomes of the world, social and political changes in Qatar have not kept pace with the country’s economic development. The expatriate and national population of the small emirate have access to luxury brands and a variety of Western goods including food as well as hotels. The high level of commercialization, however, does not mean that cultural differences between the various nationalities have been erased. Online forums and social media have provided neutral public spaces where debate and dialogue about identity and values can take place in a way they do not occur in public. This chapter examines a variety of examples through comments by expats and nationals on a number of media sites as well as Twitter, Facebook, and Instagram.

Esophageal and Gastric Disorders

2016 ◽  
pp. 241-250
Author(s):  
Amy S. Oxentenko
Keyword(s):  
Pressure Gradient ◽  
Lower Esophageal Sphincter ◽  
Negative Pressure ◽  
Positive Pressure ◽  
Gastric Contents ◽  
Esophageal Sphincter

The main functions of the esophagus are to transport food and prevent reflux. To transport food from the mouth to the stomach, the esophagus must work against a pressure gradient, with negative pressure in the chest and positive pressure in the abdomen. The lower esophageal sphincter helps to prevent reflux of gastric contents back into the esophagus.

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