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A K Webb - One of the best experts on this subject based on the ideXlab platform.
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identification of airborne dissemination of epidemic multiresistant strains of pseudomonas aeruginosa at a cf centre during a Cross Infection outbreak
Thorax, 2003Co-Authors: Andrew M Jones, John R W Govan, C J Doherty, M E Dodd, B Isalska, T N Stanbridge, A K WebbAbstract:BACKGROUND: Chronic Pseudomonas aeruginosa Infection is a major cause of morbidity and mortality for individuals with cystic fibrosis (CF). P aeruginosa Cross Infection outbreaks have recently been reported at CF holiday camps and specialist centres. The mechanism of Cross Infection is unknown. A study was performed to look for the presence of epidemic strains of P aeruginosa in the environment of a CF centre during a Cross Infection outbreak and to examine their potential modes of spread between patients. METHODS: Microbiological sampling of the environment of the CF facility was performed, including room air sampling. Individual P aeruginosa strains were identified by bacterial fingerprinting. The typing patterns were compared with those of epidemic strains responsible for Cross Infection among the patients. RESULTS: Epidemic P aeruginosa strains were isolated from room air when patients performed spirometric tests, nebulisation, and airway clearance, but were not present in other areas of the inanimate environment of the CF centre. CONCLUSIONS: Aerosol dissemination may be the most important factor in patient-to-patient spread of epidemic strains of P aeruginosa during recent Cross Infection outbreaks at adult CF centres.
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identification of airborne dissemination of epidemic multiresistant strains of pseudomonas aeruginosa at a cf centre during a Cross Infection outbreak
Thorax, 2003Co-Authors: Andrew M Jones, John R W Govan, C J Doherty, M E Dodd, B Isalska, T N Stanbridge, A K WebbAbstract:Background: Chronic Pseudomonas aeruginosa Infection is a major cause of morbidity and mortality for individuals with cystic fibrosis (CF). P aeruginosa Cross Infection outbreaks have recently been reported at CF holiday camps and specialist centres. The mechanism of Cross Infection is unknown. A study was performed to look for the presence of epidemic strains of P aeruginosa in the environment of a CF centre during a Cross Infection outbreak and to examine their potential modes of spread between patients. Methods: Microbiological sampling of the environment of the CF facility was performed, including room air sampling. Individual P aeruginosa strains were identified by bacterial fingerprinting. The typing patterns were compared with those of epidemic strains responsible for Cross Infection among the patients. Results: Epidemic P aeruginosa strains were isolated from room air when patients performed spirometric tests, nebulisation, and airway clearance, but were not present in other areas of the inanimate environment of the CF centre. Conclusions: Aerosol dissemination may be the most important factor in patient-to-patient spread of epidemic strains of P aeruginosa during recent Cross Infection outbreaks at adult CF centres.
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recent advances in Cross Infection in cystic fibrosis burkholderia cepacia complex pseudomonas aeruginosa mrsa and pandoraea spp
Journal of the Royal Society of Medicine, 2003Co-Authors: Andrew M Jones, A K WebbAbstract:Cross-Infection causes the most concern and discussion amongst cystic fibrosis (CF) health professionals, patients and carers. It causes concern because microbiological status can influence the quality of life and survival of a CF patient.1–3 The list of bacterial pathogens documented as responsible for Cross-Infection outbreaks is lengthening and currently includes Burkholderia cepacia complex, methicillinresistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Pandoraea spp.4–7 We consider current Cross-Infection problems in CF and discuss the clinical problems associated with Cross-Infection, highlighting the major pathogens involved and the consequences of Cross-Infection for individual patients, specialist centres and the CF community.
Rasmus Lund Jensen - One of the best experts on this subject based on the ideXlab platform.
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protected zone ventilation and reduced personal exposure to airborne Cross Infection
Indoor Air, 2015Co-Authors: Peter V Nielsen, Rasmus Lund Jensen, Per Heiselberg, Jorma HeikkinenAbstract:: The main objective of this study was to examine the performance of protected zone ventilation (PZV) and hybrid protected zone ventilation (HPZV) to reduce the direct exposure to exhaled air from others' breathing. Experimental measurements are carried out to test the performance of PZV in a full-scale office room with two breathing thermal manikins. The measurements were performed under three configurations, including two standing manikins at different distances: 0.35, 0.5, and 1.1 m. When the supply air velocity is increased to 4 m/s in the downward plane jet, the dimensionless concentration is 40% lower than for fully mixed ventilation, which can be considered as a measure of protection from the zoning condition. The measurement results showed that in both the PZV and the HPZV system it is possible to decrease the transmission of tracer gas from one manikin to the opposite manikin; therefore, it probably would reduce the risk of air borne Cross-Infection between two people at the same relative positions. The results suggest that PZV and HPZV may be used to reduce the exposure of people in a protected zone from indoor pollutants emitted in a source zone.
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the risk of airborne Cross Infection in a room with vertical low velocity ventilation
Indoor Air, 2013Co-Authors: Ines Olmedo, Peter V Nielsen, Ruiz M De Adana, Rasmus Lund JensenAbstract:UNLABELLED: Downward flow ventilation systems are one of the most recommended ventilation strategies when contaminants in rooms must be removed and people must be protected from the risk of airborne Cross-Infection. This study is based on experimental tests carried out in a room with downward flow ventilation. Two breathing thermal manikins are placed in a room face to face. One manikin's breathing is considered to be the contaminated source to simulate a risky situation with airborne Cross-Infection. The position of the manikins in relation to the diffuser and the location of diffuser in the room as well as the distance between the manikins are being changed to observe the influence of these factors on the personal exposure of the target manikin. The results show that the DWF in different situations often is unable to penetrate the microenvironment generated by the manikins. The downward ventilation system can give an unexpected high level of contaminant exposure of the target manikin, when the distance between the manikins is reduced. PRACTICAL IMPLICATIONS: Several guidelines recommend the downward ventilation system to reduce the risk of Cross-Infection between people in hospital rooms. This study shows that this recommendation should be taken into careful consideration. It is important to be aware of people position, position to other thermal loads in the room, and especially be aware of the distance between people if the exposure to the exhaled contaminants wants to be reduced.
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the risk of airborne Cross Infection in a room with vertical low velocity ventilation
Indoor Air, 2013Co-Authors: Ines Olmedo, Peter V Nielsen, Ruiz M De Adana, Rasmus Lund JensenAbstract:In recent years, there has been a great interest infinding the most efficient ventilation strategy to pro-duce a comfortable indoor climate for people, and atthe same time preventing the spreads of contaminantsAbstract Downward flow ventilation systems are one of the most recommendedventilation strategies when contaminants in rooms must be removed andpeople must be protected from the risk of airborne Cross-Infection. This study isbased on experimental tests carried out in a room with downward flow venti-lation. Two breathing thermal manikins are placed in a room face to face. Onemanikin Department of Civil Engineering, Aalborg University,s breathing is considered to be the contaminated source to simulate arisky situation with airborne Cross-Infection. The position of the manikins inrelation to the diffuser and the location of diffuser in the room as well as thedistance between the manikins are being changed to observe the influence ofthese factors on the personal exposure of the target manikin. The results showthat the DWF in different situations often is unable to penetrate the microen-vironment generated by the manikins. The downward ventilation system can givean unexpected high level of contaminant exposure of the target manikin, whenthe distance between the manikins is reduced.
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airborne Cross Infection risk between two people standing in surroundings with a vertical temperature gradient
Hvac&r Research, 2012Co-Authors: Peter V Nielsen, Ines Olmedo, Manuel Ruiz De Adana, Piotr Grzelecki, Rasmus Lund JensenAbstract:The transmission of exhaled small particles from one person to another in an indoor environment can take place both directly (in the microenvironment around the persons) and via the room air distribution. The impact of these transmission routes for two persons is investigated in detail by evaluating the exposure to gaseous substances (simulating particles <5 μm) in a room with a vertical temperature gradient obtained by displacement ventilation. Experiments are conducted with two breathing thermal manikins—one the source and the other the target. In the experiments, the distance between the two manikins varies from 1.1 to 0.35 m (43 to 14 in.). A tracer gas N2O is used to represent the gaseous substances exhaled by the source manikin. The concentration of N2O is measured to study the impact on the exposure of the distance between manikins and manikin positions (face to face, face to the side of the target manikin, face to the back of the target manikin, and a seated source manikin). The exposure increases...
Ines Olmedo - One of the best experts on this subject based on the ideXlab platform.
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influence of human breathing modes on airborne Cross Infection risk
Building and Environment, 2016Co-Authors: J M Villafruela, Ines Olmedo, San J JoseAbstract:Abstract CFD simulation is an accurate and reliable method to predict the risk of airborne Cross-Infection in a room. This paper focuses on the validation of a 3-D transient CFD model used to predict personal exposure to airborne pathogens and Infection risk in a displacement ventilated room. The model provides spatial and temporal solutions of the airflow pattern in the room (temperature, velocity and turbulence), as well as contaminant concentration in a room where two thermal manikins simulate two standing people, one of whom exhales a tracer gas N2O simulating airborne contaminants. Numerical results are validated with experimental data and the model shows a high accuracy when predicting the transient cases studied. Once the model is validated, the CFD model is used to simulate different airborne Cross-Infection risk scenarios. Four different combinations of the manikins’ breathing modes and four different separation distances between the two manikins are studied. The results show that exhaling through the nose or mouth disperses exhaled contaminants in a completely different way and also means that exhaled contaminants are received differently. For short separation distances between breathing sources the interaction between breaths is a key factor in the airborne Cross-Infection for all the breathing mode combinations studied. However, for long distances the general airflow conditions in the room prove to be more important.
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the risk of airborne Cross Infection in a room with vertical low velocity ventilation
Indoor Air, 2013Co-Authors: Ines Olmedo, Peter V Nielsen, Ruiz M De Adana, Rasmus Lund JensenAbstract:UNLABELLED: Downward flow ventilation systems are one of the most recommended ventilation strategies when contaminants in rooms must be removed and people must be protected from the risk of airborne Cross-Infection. This study is based on experimental tests carried out in a room with downward flow ventilation. Two breathing thermal manikins are placed in a room face to face. One manikin's breathing is considered to be the contaminated source to simulate a risky situation with airborne Cross-Infection. The position of the manikins in relation to the diffuser and the location of diffuser in the room as well as the distance between the manikins are being changed to observe the influence of these factors on the personal exposure of the target manikin. The results show that the DWF in different situations often is unable to penetrate the microenvironment generated by the manikins. The downward ventilation system can give an unexpected high level of contaminant exposure of the target manikin, when the distance between the manikins is reduced. PRACTICAL IMPLICATIONS: Several guidelines recommend the downward ventilation system to reduce the risk of Cross-Infection between people in hospital rooms. This study shows that this recommendation should be taken into careful consideration. It is important to be aware of people position, position to other thermal loads in the room, and especially be aware of the distance between people if the exposure to the exhaled contaminants wants to be reduced.
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the risk of airborne Cross Infection in a room with vertical low velocity ventilation
Indoor Air, 2013Co-Authors: Ines Olmedo, Peter V Nielsen, Ruiz M De Adana, Rasmus Lund JensenAbstract:In recent years, there has been a great interest infinding the most efficient ventilation strategy to pro-duce a comfortable indoor climate for people, and atthe same time preventing the spreads of contaminantsAbstract Downward flow ventilation systems are one of the most recommendedventilation strategies when contaminants in rooms must be removed andpeople must be protected from the risk of airborne Cross-Infection. This study isbased on experimental tests carried out in a room with downward flow venti-lation. Two breathing thermal manikins are placed in a room face to face. Onemanikin Department of Civil Engineering, Aalborg University,s breathing is considered to be the contaminated source to simulate arisky situation with airborne Cross-Infection. The position of the manikins inrelation to the diffuser and the location of diffuser in the room as well as thedistance between the manikins are being changed to observe the influence ofthese factors on the personal exposure of the target manikin. The results showthat the DWF in different situations often is unable to penetrate the microen-vironment generated by the manikins. The downward ventilation system can givean unexpected high level of contaminant exposure of the target manikin, whenthe distance between the manikins is reduced.
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airborne Cross Infection risk between two people standing in surroundings with a vertical temperature gradient
Hvac&r Research, 2012Co-Authors: Peter V Nielsen, Ines Olmedo, Manuel Ruiz De Adana, Piotr Grzelecki, Rasmus Lund JensenAbstract:The transmission of exhaled small particles from one person to another in an indoor environment can take place both directly (in the microenvironment around the persons) and via the room air distribution. The impact of these transmission routes for two persons is investigated in detail by evaluating the exposure to gaseous substances (simulating particles <5 μm) in a room with a vertical temperature gradient obtained by displacement ventilation. Experiments are conducted with two breathing thermal manikins—one the source and the other the target. In the experiments, the distance between the two manikins varies from 1.1 to 0.35 m (43 to 14 in.). A tracer gas N2O is used to represent the gaseous substances exhaled by the source manikin. The concentration of N2O is measured to study the impact on the exposure of the distance between manikins and manikin positions (face to face, face to the side of the target manikin, face to the back of the target manikin, and a seated source manikin). The exposure increases...
Peter V Nielsen - One of the best experts on this subject based on the ideXlab platform.
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protected zone ventilation and reduced personal exposure to airborne Cross Infection
Indoor Air, 2015Co-Authors: Peter V Nielsen, Rasmus Lund Jensen, Per Heiselberg, Jorma HeikkinenAbstract:: The main objective of this study was to examine the performance of protected zone ventilation (PZV) and hybrid protected zone ventilation (HPZV) to reduce the direct exposure to exhaled air from others' breathing. Experimental measurements are carried out to test the performance of PZV in a full-scale office room with two breathing thermal manikins. The measurements were performed under three configurations, including two standing manikins at different distances: 0.35, 0.5, and 1.1 m. When the supply air velocity is increased to 4 m/s in the downward plane jet, the dimensionless concentration is 40% lower than for fully mixed ventilation, which can be considered as a measure of protection from the zoning condition. The measurement results showed that in both the PZV and the HPZV system it is possible to decrease the transmission of tracer gas from one manikin to the opposite manikin; therefore, it probably would reduce the risk of air borne Cross-Infection between two people at the same relative positions. The results suggest that PZV and HPZV may be used to reduce the exposure of people in a protected zone from indoor pollutants emitted in a source zone.
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the risk of airborne Cross Infection in a room with vertical low velocity ventilation
Indoor Air, 2013Co-Authors: Ines Olmedo, Peter V Nielsen, Ruiz M De Adana, Rasmus Lund JensenAbstract:UNLABELLED: Downward flow ventilation systems are one of the most recommended ventilation strategies when contaminants in rooms must be removed and people must be protected from the risk of airborne Cross-Infection. This study is based on experimental tests carried out in a room with downward flow ventilation. Two breathing thermal manikins are placed in a room face to face. One manikin's breathing is considered to be the contaminated source to simulate a risky situation with airborne Cross-Infection. The position of the manikins in relation to the diffuser and the location of diffuser in the room as well as the distance between the manikins are being changed to observe the influence of these factors on the personal exposure of the target manikin. The results show that the DWF in different situations often is unable to penetrate the microenvironment generated by the manikins. The downward ventilation system can give an unexpected high level of contaminant exposure of the target manikin, when the distance between the manikins is reduced. PRACTICAL IMPLICATIONS: Several guidelines recommend the downward ventilation system to reduce the risk of Cross-Infection between people in hospital rooms. This study shows that this recommendation should be taken into careful consideration. It is important to be aware of people position, position to other thermal loads in the room, and especially be aware of the distance between people if the exposure to the exhaled contaminants wants to be reduced.
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the risk of airborne Cross Infection in a room with vertical low velocity ventilation
Indoor Air, 2013Co-Authors: Ines Olmedo, Peter V Nielsen, Ruiz M De Adana, Rasmus Lund JensenAbstract:In recent years, there has been a great interest infinding the most efficient ventilation strategy to pro-duce a comfortable indoor climate for people, and atthe same time preventing the spreads of contaminantsAbstract Downward flow ventilation systems are one of the most recommendedventilation strategies when contaminants in rooms must be removed andpeople must be protected from the risk of airborne Cross-Infection. This study isbased on experimental tests carried out in a room with downward flow venti-lation. Two breathing thermal manikins are placed in a room face to face. Onemanikin Department of Civil Engineering, Aalborg University,s breathing is considered to be the contaminated source to simulate arisky situation with airborne Cross-Infection. The position of the manikins inrelation to the diffuser and the location of diffuser in the room as well as thedistance between the manikins are being changed to observe the influence ofthese factors on the personal exposure of the target manikin. The results showthat the DWF in different situations often is unable to penetrate the microen-vironment generated by the manikins. The downward ventilation system can givean unexpected high level of contaminant exposure of the target manikin, whenthe distance between the manikins is reduced.
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airborne Cross Infection risk between two people standing in surroundings with a vertical temperature gradient
Hvac&r Research, 2012Co-Authors: Peter V Nielsen, Ines Olmedo, Manuel Ruiz De Adana, Piotr Grzelecki, Rasmus Lund JensenAbstract:The transmission of exhaled small particles from one person to another in an indoor environment can take place both directly (in the microenvironment around the persons) and via the room air distribution. The impact of these transmission routes for two persons is investigated in detail by evaluating the exposure to gaseous substances (simulating particles <5 μm) in a room with a vertical temperature gradient obtained by displacement ventilation. Experiments are conducted with two breathing thermal manikins—one the source and the other the target. In the experiments, the distance between the two manikins varies from 1.1 to 0.35 m (43 to 14 in.). A tracer gas N2O is used to represent the gaseous substances exhaled by the source manikin. The concentration of N2O is measured to study the impact on the exposure of the distance between manikins and manikin positions (face to face, face to the side of the target manikin, face to the back of the target manikin, and a seated source manikin). The exposure increases...
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dispersion of exhalation pollutants in a two bed hospital ward with a downward ventilation system
Building and Environment, 2008Co-Authors: Hua Qian, Peter V Nielsen, Carl Erik HyldgaardAbstract:Abstract The Centers for Disease Control and Prevention has recommended the use of downward ventilation systems in isolation rooms to reduce the risk of Cross-Infection from airborne transmissible diseases. The expected airflow pattern of a downward ventilation design would supply cooler and slightly heavier clean air from a ceiling diffuser to push down contaminants, which would then be removed via outlets at floor level. A “laminar” (strictly speaking, unidirectional) flow is expected to be produced to avoid flow mixing and thus reduce Cross-Infection risk. Experiments were carried out in a full-scale experimental hospital ward with a downward ventilation system to investigate the possibility of applying downward ventilation in a general hospital ward. Two life-sized breathing thermal manikins were used to simulate a source patient and a receiving patient. Computation fluid dynamics was also used to investigate the airflow pattern and pollutant dispersion in the test ward. Based on both experimental and numerical results, the laminar airflow pattern was shown to be impossible to achieve due to turbulent flow mixing and flow entrainment into the supply air stream. The thermal plumes produced above people were found to induce flow mixing. We also studied the effects of the locations of the supply and extraction openings on both the flow pattern and pollutant exposure level in the occupied zone. A number of practical recommendations are suggested.
Andrew M Jones - One of the best experts on this subject based on the ideXlab platform.
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identification of airborne dissemination of epidemic multiresistant strains of pseudomonas aeruginosa at a cf centre during a Cross Infection outbreak
Thorax, 2003Co-Authors: Andrew M Jones, John R W Govan, C J Doherty, M E Dodd, B Isalska, T N Stanbridge, A K WebbAbstract:BACKGROUND: Chronic Pseudomonas aeruginosa Infection is a major cause of morbidity and mortality for individuals with cystic fibrosis (CF). P aeruginosa Cross Infection outbreaks have recently been reported at CF holiday camps and specialist centres. The mechanism of Cross Infection is unknown. A study was performed to look for the presence of epidemic strains of P aeruginosa in the environment of a CF centre during a Cross Infection outbreak and to examine their potential modes of spread between patients. METHODS: Microbiological sampling of the environment of the CF facility was performed, including room air sampling. Individual P aeruginosa strains were identified by bacterial fingerprinting. The typing patterns were compared with those of epidemic strains responsible for Cross Infection among the patients. RESULTS: Epidemic P aeruginosa strains were isolated from room air when patients performed spirometric tests, nebulisation, and airway clearance, but were not present in other areas of the inanimate environment of the CF centre. CONCLUSIONS: Aerosol dissemination may be the most important factor in patient-to-patient spread of epidemic strains of P aeruginosa during recent Cross Infection outbreaks at adult CF centres.
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identification of airborne dissemination of epidemic multiresistant strains of pseudomonas aeruginosa at a cf centre during a Cross Infection outbreak
Thorax, 2003Co-Authors: Andrew M Jones, John R W Govan, C J Doherty, M E Dodd, B Isalska, T N Stanbridge, A K WebbAbstract:Background: Chronic Pseudomonas aeruginosa Infection is a major cause of morbidity and mortality for individuals with cystic fibrosis (CF). P aeruginosa Cross Infection outbreaks have recently been reported at CF holiday camps and specialist centres. The mechanism of Cross Infection is unknown. A study was performed to look for the presence of epidemic strains of P aeruginosa in the environment of a CF centre during a Cross Infection outbreak and to examine their potential modes of spread between patients. Methods: Microbiological sampling of the environment of the CF facility was performed, including room air sampling. Individual P aeruginosa strains were identified by bacterial fingerprinting. The typing patterns were compared with those of epidemic strains responsible for Cross Infection among the patients. Results: Epidemic P aeruginosa strains were isolated from room air when patients performed spirometric tests, nebulisation, and airway clearance, but were not present in other areas of the inanimate environment of the CF centre. Conclusions: Aerosol dissemination may be the most important factor in patient-to-patient spread of epidemic strains of P aeruginosa during recent Cross Infection outbreaks at adult CF centres.
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recent advances in Cross Infection in cystic fibrosis burkholderia cepacia complex pseudomonas aeruginosa mrsa and pandoraea spp
Journal of the Royal Society of Medicine, 2003Co-Authors: Andrew M Jones, A K WebbAbstract:Cross-Infection causes the most concern and discussion amongst cystic fibrosis (CF) health professionals, patients and carers. It causes concern because microbiological status can influence the quality of life and survival of a CF patient.1–3 The list of bacterial pathogens documented as responsible for Cross-Infection outbreaks is lengthening and currently includes Burkholderia cepacia complex, methicillinresistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Pandoraea spp.4–7 We consider current Cross-Infection problems in CF and discuss the clinical problems associated with Cross-Infection, highlighting the major pathogens involved and the consequences of Cross-Infection for individual patients, specialist centres and the CF community.