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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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Variability of maximum spatially-averaged velocity magnitude across the 36 trials.
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Fig5: Variability of maximum spatially-averaged velocity magnitude across the 36 trials.

Mentions: As would be expected from the limitation on the PIV window size and the variable physical traits of study participants, it was found that there was considerable variation in location and strength of each cough, with some coughs missing most of the imaged field of view entirely. The distribution of values of the spatially-averaged maximum velocity magnitude is illustrated in Figure 5. The average value across all 36 coughs is 0.52 m/s, but with the data from the three poor quality experiments removed, the average across the remaining 27 tests is 0.41 m/s. These values indicate that there is significant air motion during a cough, of the order of 0.5 m/s, at a location as far away as 1 m from the person who is coughing. During the set-up phase for this preliminary study, a single volunteer produced 5 coughs, with a 180-mm-wide PIV field being located at different distances from the mouth for each cough. The participant attempted to produce a series of coughs each of the same strength. Although the quality of the resulting vector field was not sufficient to provide quantitative data, it was possible to identify the arrival of the cough front at each location and, thereby, estimate the velocity of the cough front at the centre of each field of view. The results are shown in Figure 6, illustrating the rapid decrease in velocity in the near-field of the mouth, as would be expected. At 1 m from the mouth the cough front velocity has a magnitude in agreement with the average of the spatially-averaged maximum velocity magnitude from our preliminary study with 12 healthy participants. Note that the fitted curve is based on an approximation of a linear growth of the cough jet diameter with distance from the mouth.Figure 4


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)

Variability of maximum spatially-averaged velocity magnitude across the 36 trials.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig5: Variability of maximum spatially-averaged velocity magnitude across the 36 trials.
Mentions: As would be expected from the limitation on the PIV window size and the variable physical traits of study participants, it was found that there was considerable variation in location and strength of each cough, with some coughs missing most of the imaged field of view entirely. The distribution of values of the spatially-averaged maximum velocity magnitude is illustrated in Figure 5. The average value across all 36 coughs is 0.52 m/s, but with the data from the three poor quality experiments removed, the average across the remaining 27 tests is 0.41 m/s. These values indicate that there is significant air motion during a cough, of the order of 0.5 m/s, at a location as far away as 1 m from the person who is coughing. During the set-up phase for this preliminary study, a single volunteer produced 5 coughs, with a 180-mm-wide PIV field being located at different distances from the mouth for each cough. The participant attempted to produce a series of coughs each of the same strength. Although the quality of the resulting vector field was not sufficient to provide quantitative data, it was possible to identify the arrival of the cough front at each location and, thereby, estimate the velocity of the cough front at the centre of each field of view. The results are shown in Figure 6, illustrating the rapid decrease in velocity in the near-field of the mouth, as would be expected. At 1 m from the mouth the cough front velocity has a magnitude in agreement with the average of the spatially-averaged maximum velocity magnitude from our preliminary study with 12 healthy participants. Note that the fitted curve is based on an approximation of a linear growth of the cough jet diameter with distance from the mouth.Figure 4

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