Dataset Information

Qualitative real-time schlieren and shadowgraph imaging of human exhaled airflows: an aid to aerosol infection control.

ABSTRACT: Using a newly constructed airflow imaging system, airflow patterns were visualized that were associated with common, everyday respiratory activities (e.g. breathing, talking, laughing, whistling). The effectiveness of various interventions (e.g. putting hands and tissues across the mouth and nose) to reduce the potential transmission of airborne infection, whilst coughing and sneezing, were also investigated. From the digital video footage recorded, it was seen that both coughing and sneezing are relatively poorly contained by commonly used configurations of single-handed shielding maneuvers. Only some but not all of the forward momentum of the cough and sneeze puffs are curtailed with various hand techniques, and the remaining momentum is disseminated in a large puff in the immediate vicinity of the cougher, which may still act as a nearby source of infection. The use of a tissue (in this case, 4-ply, opened and ready in the hand) proved to be surprisingly effective, though the effectiveness of this depends on the tissue remaining intact and not ripping apart. Interestingly, the use of a novel 'coughcatcher' device appears to be relatively effective in containing coughs and sneezes. One aspect that became evident during the experimental procedures was that the effectiveness of all of these barrier interventions is very much dependent on the speed with which the user can put them into position to cover the mouth and nose effectively.From these qualitative schlieren and shadowgraph imaging experiments, it is clear that making some effort to contain one's cough or sneeze puffs is worthwhile. Obviously, there will be a large amount of variation between individuals in the exact hand or tissue (the most common methods) configuration used for this and other practical factors may hinder such maneuvers in daily life, for example, when carrying shopping bags or managing young children.

SUBMITTER: Tang JW

PROVIDER: S-EPMC3120871 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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Publications

Qualitative real-time schlieren and shadowgraph imaging of human exhaled airflows: an aid to aerosol infection control.

Tang Julian W JW Nicolle Andre D G AD Pantelic Jovan J Jiang Mingxiu M Sekhr Chandra C Cheong David K W DK Tham Kwok Wai KW

PloS one 20110622 6

Using a newly constructed airflow imaging system, airflow patterns were visualized that were associated with common, everyday respiratory activities (e.g. breathing, talking, laughing, whistling). The effectiveness of various interventions (e.g. putting hands and tissues across the mouth and nose) to reduce the potential transmission of airborne infection, whilst coughing and sneezing, were also investigated. From the digital video footage recorded, it was seen that both coughing and sneezing ar ...[more]

PMID: 21731730

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Project description:Cough airflow dynamics have been previously studied using a variety of experimental methods. In this study, real-time, non-invasive shadowgraph imaging was applied to obtain additional analyses of cough airflows produced by healthy volunteers. Twenty healthy volunteers (10 women, mean age 32.2±12.9 years; 10 men, mean age 25.3±2.5 years) were asked to cough freely, then into their sleeves (as per current US CDC recommendations) in this study to analyze cough airflow dynamics. For the 10 females (cases 1-10), their maximum detectable cough propagation distances ranged from 0.16-0.55 m, with maximum derived velocities of 2.2-5.0 m/s, and their maximum detectable 2-D projected areas ranged from 0.010-0.11 m(2), with maximum derived expansion rates of 0.15-0.55 m(2)/s. For the 10 males (cases 11-20), their maximum detectable cough propagation distances ranged from 0.31-0.64 m, with maximum derived velocities of 3.2-14 m/s, and their maximum detectable 2-D projected areas ranged from 0.04-0.14 m(2), with maximum derived expansion rates of 0.25-1.4 m(2)/s. These peak velocities were measured when the visibility of the exhaled airflows was optimal and compare favorably with those reported previously using other methods, and may be seen as a validation of these previous approaches in a more natural setting. However, the propagation distances can only represent a lower limit due to the inability of the shadowgraph method to visualize these cough airflows once their temperature cools to that of the ambient air, which is an important limitation of this methodology. The qualitative high-speed video footage of these volunteers coughing into their sleeves demonstrates that although this method rarely completely blocks the cough airflow, it decelerates, splits and redirects the airflow, eventually reducing its propagation. The effectiveness of this intervention depends on optimum positioning of the arm over the nose and mouth during coughing, though unsightly stains on sleeves may make it unacceptable to some.

Dataset Information

Qualitative real-time schlieren and shadowgraph imaging of human exhaled airflows: an aid to aerosol infection control.

Publications

Qualitative real-time schlieren and shadowgraph imaging of human exhaled airflows: an aid to aerosol infection control.

Similar Datasets

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