Air Movement Visualization in the Workplace: Current Methods and New Approaches

Maynard, A.; Thompson, JP; Cain, J. R.; Rajan, Bob

doi:10.1080/778879052

Cited by 1 publication

(1 citation statement)

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“…Many natural human activities also have the potential to disseminate infectious aerosols, such as breathing, talking, coughing, sneezing and even singing, which may be a particularly effective means of transmitting airborne infection (Cole & Cook 1998;Edwards et al 2004;. More recently, there have been several inter-disciplinary reviews involving both microbiologists and engineers (Tang et al 2006;Li et al 2007), as well as cross-disciplinary studies involving both physicians and engineers examining the risks of airborne transmission from droplet dispersion and using airflow visualization in different clinical scenarios, including some simulated environments (Qian et al 2006;Xie et al 2006Xie et al , 2007 and others involving 'real-life' operating theatres and the workplace (Kim & Flynn 1991;Maynard et al 2000;Pan et al 2003;Brohus et al 2006).…”

Section: Airborne Infection In Hospitalsmentioning

confidence: 99%

A schlieren optical study of the human cough with and without wearing masks for aerosol infection control

Tang

Liebner

Craven

et al. 2009

J. R. Soc. Interface.

293

294

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Various infectious agents are known to be transmitted naturally via respiratory aerosols produced by infected patients. Such aerosols may be produced during normal activities by breathing, talking, coughing and sneezing. The schlieren optical method, previously applied mostly in engineering and physics, can be effectively used here to visualize airflows around human subjects in such indoor situations, non-intrusively and without the need for either tracer gas or airborne particles. It accomplishes this by rendering visible the optical phase gradients owing to real-time changes in air temperature. In this study, schlieren video records are obtained of human volunteers coughing with and without wearing standard surgical and N95 masks. The object is to characterize the exhaled airflows and evaluate the effect of these commonly used masks on the fluid-dynamic mechanisms that spread infection by coughing. Further, a high-speed schlieren video of a single cough is analysed by a computerized method of tracking individual turbulent eddies, demonstrating the non-intrusive velocimetry of the expelled airflow. Results show that human coughing projects a rapid turbulent jet into the surrounding air, but that wearing a surgical or N95 mask thwarts this natural mechanism of transmitting airborne infection, either by blocking the formation of the jet (N95 mask), or by redirecting it in a less harmful direction (surgical mask).

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