National Air Transportation Center of Excellence for Research in the Intermodal Transport Environment, School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, IN 47906-2088, USA.
Indoor Air. 2010 Feb;20(1):31-9. doi: 10.1111/j.1600-0668.2009.00623.x. Epub 2009 Sep 11.
The exhaled air of infected humans is one of the prime sources of contagious viruses. The exhaled air comes from respiratory events such as the coughing, sneezing, breathing and talking. Accurate information on the thermo-fluid characteristics of the exhaled airflow can be important for prediction of infectious disease transmission. The present study developed a source model to provide the thermo-fluid conditions of the exhaled air from the breathing and talking processes. The source model is a set of equations obtained from the measurements of the flow rate, flow direction, and area of mouth/nose opening with human subjects. It was found that the exhaled flow rate over time can be represented as a sinusoidal function for breathing and a constant for talking. The flow rates can be calculated by physiological parameters of a subject. The direction of the exhalation jet did not vary much between subjects and the area of mouth/nose opening could be regarded as a constant. Though the mouth/nose opening size varied among subjects, they were not correlated with the physiological parameters of the subjects. If combined with appropriate virus and droplet distribution information, the model can be used to describe the disease source due to breathing and talking.
Accurate prediction of airborne disease transmission, and the infection prone zones, can aid in identifying and implementing the control strategies. With the recent advancements, Computational Fluid Dynamics (CFD) has become a powerful tool in predicting the disease transmission. Accurate prediction of the transmission by these CFD simulations requires information on sources and sinks of infectious viruses and models for dispersion of these viruses. The exhaled air of an infected human is one of the prime sources of disease viruses. In the present study, measurements of the flow were conducted on human subjects to develop models for the flow boundary conditions for the exhalation and inhalation during breathing and talking.
感染者呼出的空气是传染性病毒的主要来源之一。呼出的空气来自于呼吸事件，如咳嗽、打喷嚏、呼吸和说话。准确了解呼出气流的热流特性对于预测传染病的传播非常重要。本研究开发了一种源模型，以提供呼吸和说话过程中呼出空气的热流特性。源模型是一组通过对人体进行流量、流向和口/鼻开口面积测量得到的方程。研究发现，随时间变化的呼出流量可以表示为呼吸时的正弦函数和说话时的常数。流量可以通过受试者的生理参数计算得出。呼气射流的方向在受试者之间变化不大，口/鼻开口面积可以视为常数。尽管口/鼻开口大小在受试者之间有所不同，但它们与受试者的生理参数没有相关性。如果与适当的病毒和液滴分布信息相结合，该模型可用于描述呼吸和说话引起的疾病源。
准确预测空气传播疾病的传播和感染易感染区，有助于识别和实施控制策略。随着最近的进展，计算流体动力学 (CFD) 已成为预测疾病传播的有力工具。这些 CFD 模拟的准确预测需要有关传染性病毒的源和汇以及这些病毒的扩散模型的信息。感染者呼出的空气是疾病病毒的主要来源之一。在本研究中，对人体进行了流量测量，以开发呼吸和说话时呼气和吸气的流动边界条件模型。
