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Western Cold and Flu (WeCoF) aerosol study--preliminary results.

Savory E, Lin WE, Blackman K, Roberto MC, Cuthbertson LR, Scott JA, Mubareka S - BMC Res Notes (2014)

Bottom Line: The peak value of velocity was also extracted and compared with the average velocity.Preliminary results show that there is significant air motion associated with a cough (on the order of 0.5 m/s) as far away as 1 m from the mouth of the healthy person who coughs.The results from this pilot study provide the framework for a more extensive participant recruitment campaign that will encompass a statistically-significant cohort.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical & Materials Engineering, The University of Western Ontario, 1151 Richmond Street North, London N6A 5B9, Canada. wlin26@uwo.ca.

ABSTRACT

Background: Influenza virus is responsible for annual deaths due to seasonal epidemics and is the cause of major pandemics which have claimed millions of human lives over the last century. Knowledge about respiratory virus transmission is advancing. Spread is likely through the air, but much work remains to be done to characterize the aerosols produced by infected individuals, including viral particle survival and infectivity. Although coughs have been characterized, little work has been done to examine coughs from infected individuals. The WeCoF project aims at providing evidence to support prevention measures to mitigate person-to-person influenza transmission in critical locations, such as hospitals, and during pandemics.

Findings: A novel experimental cough chamber facility - the FLUGIE - has been developed to study the far-field aerodynamics and aerosol transport of droplets produced by the coughs from humans naturally-infected with influenza. The flow field of each cough is measured using Particle Image Velocimetry (PIV). A preliminary study involving 12 healthy individuals has been carried out in order to quantify the strengths of their coughs at a distance of 1 m from the mouth. The spatially averaged maximum velocity was determined and the average value was 0.41 m/s across 27 coughs of good data quality. The peak value of velocity was also extracted and compared with the average velocity.

Conclusions: Preliminary results show that there is significant air motion associated with a cough (on the order of 0.5 m/s) as far away as 1 m from the mouth of the healthy person who coughs. The results from this pilot study provide the framework for a more extensive participant recruitment campaign that will encompass a statistically-significant cohort.

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Related in: MedlinePlus

Field of view for the cough airflow measurements (left) and an example of an instantaneous vector field obtained during a cough (right).
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Fig3: Field of view for the cough airflow measurements (left) and an example of an instantaneous vector field obtained during a cough (right).

Mentions: Preliminary experiments have been carried out involving 12 healthy volunteer participants (9 male, 3 female, ages 20 to 32). Since they were healthy, cough airflow measurements using PIV were conducted without viral aerosol sampling. Each participant produced 3 coughs with the PIV system recording image pairs prior to, during and after the cough. These were then processed to yield instantaneous velocity vector arrays within the field of view. Figure 3 (left) shows that the field of view was located 1.00 m downstream of the entry to the FLUGIE cough chamber and encompassed a region of 174.8 mm in the streamwise direction, centred at the 1.00 m location. The field of view extended over 233.1 mm vertically and was below the level of the cough to take into account the fact that, even if the cough was initially directed horizontally forward by the study participant, most of the coughs had drifted downwards at the 1 m location, contradicting the importance of buoyancy in a proposed model based on visualizations out to 0.70 m from a participant in an open laboratory setting[55]. An example of a processed vector field is shown in Figure 3 (right), where the green arrows are vectors that have passed validation by the Insight3G processing software. Red vectors are spurious values, which were typically attributable to the reduced light sheet intensity at the edges of the field-of-view, whose size approached the upper limits of this PIV equipment. Based on the selected interrogation window size (i.e. the area from which a vector was calculated), the maximum possible number of vectors in each processed image was 3,816.Figure 3


Western Cold and Flu (WeCoF) aerosol study--preliminary results.

Savory E, Lin WE, Blackman K, Roberto MC, Cuthbertson LR, Scott JA, Mubareka S - BMC Res Notes (2014)

Field of view for the cough airflow measurements (left) and an example of an instantaneous vector field obtained during a cough (right).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4150972&req=5

Fig3: Field of view for the cough airflow measurements (left) and an example of an instantaneous vector field obtained during a cough (right).
Mentions: Preliminary experiments have been carried out involving 12 healthy volunteer participants (9 male, 3 female, ages 20 to 32). Since they were healthy, cough airflow measurements using PIV were conducted without viral aerosol sampling. Each participant produced 3 coughs with the PIV system recording image pairs prior to, during and after the cough. These were then processed to yield instantaneous velocity vector arrays within the field of view. Figure 3 (left) shows that the field of view was located 1.00 m downstream of the entry to the FLUGIE cough chamber and encompassed a region of 174.8 mm in the streamwise direction, centred at the 1.00 m location. The field of view extended over 233.1 mm vertically and was below the level of the cough to take into account the fact that, even if the cough was initially directed horizontally forward by the study participant, most of the coughs had drifted downwards at the 1 m location, contradicting the importance of buoyancy in a proposed model based on visualizations out to 0.70 m from a participant in an open laboratory setting[55]. An example of a processed vector field is shown in Figure 3 (right), where the green arrows are vectors that have passed validation by the Insight3G processing software. Red vectors are spurious values, which were typically attributable to the reduced light sheet intensity at the edges of the field-of-view, whose size approached the upper limits of this PIV equipment. Based on the selected interrogation window size (i.e. the area from which a vector was calculated), the maximum possible number of vectors in each processed image was 3,816.Figure 3

Bottom Line: The peak value of velocity was also extracted and compared with the average velocity.Preliminary results show that there is significant air motion associated with a cough (on the order of 0.5 m/s) as far away as 1 m from the mouth of the healthy person who coughs.The results from this pilot study provide the framework for a more extensive participant recruitment campaign that will encompass a statistically-significant cohort.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical & Materials Engineering, The University of Western Ontario, 1151 Richmond Street North, London N6A 5B9, Canada. wlin26@uwo.ca.

ABSTRACT

Background: Influenza virus is responsible for annual deaths due to seasonal epidemics and is the cause of major pandemics which have claimed millions of human lives over the last century. Knowledge about respiratory virus transmission is advancing. Spread is likely through the air, but much work remains to be done to characterize the aerosols produced by infected individuals, including viral particle survival and infectivity. Although coughs have been characterized, little work has been done to examine coughs from infected individuals. The WeCoF project aims at providing evidence to support prevention measures to mitigate person-to-person influenza transmission in critical locations, such as hospitals, and during pandemics.

Findings: A novel experimental cough chamber facility - the FLUGIE - has been developed to study the far-field aerodynamics and aerosol transport of droplets produced by the coughs from humans naturally-infected with influenza. The flow field of each cough is measured using Particle Image Velocimetry (PIV). A preliminary study involving 12 healthy individuals has been carried out in order to quantify the strengths of their coughs at a distance of 1 m from the mouth. The spatially averaged maximum velocity was determined and the average value was 0.41 m/s across 27 coughs of good data quality. The peak value of velocity was also extracted and compared with the average velocity.

Conclusions: Preliminary results show that there is significant air motion associated with a cough (on the order of 0.5 m/s) as far away as 1 m from the mouth of the healthy person who coughs. The results from this pilot study provide the framework for a more extensive participant recruitment campaign that will encompass a statistically-significant cohort.

Show MeSH
Related in: MedlinePlus