Department of Civil and Architectural Engineering (retitled from Building and Construction), City University of Hong Kong, Kowloon Tong, Hong Kong, People's Republic of China.
J R Soc Interface. 2012 May 7;9(70):938-48. doi: 10.1098/rsif.2011.0537. Epub 2011 Sep 21.
Facemasks are widely used as a protective measure by general public to prevent inhalation of airborne pathogens including seasonal, swine and other forms of influenza and severe acute respiratory syndrome (SARS), etc. However, scientific data on effectiveness of facemasks in reducing infections in the community are extremely limited and even inconsistent. In this work, two manikins labelled as 'source' and 'susceptible' were used to measure the protection provided by facemasks under various emission scenarios. The source was modified to generate polydisperse ultrafine particles, whereas the susceptible was modified to mimic a realistic breathing pattern. The facemask was challenged by both pseudo-steady and highly transient emissions generated by an expiratory process where parameters, such as separation distance between manikins, emission velocity and expiratory duration, were controlled and measured systematically. Performances of four different types of facemask fits, varying from ideal to normal wearing practice, were also investigated. Under the pseudo-steady concentration environment, facemask protection was found to be 45 per cent, while under expiratory emissions, protection varied from 33 to 100 per cent. It was also observed that the separation between the source and the manikin was the most influential parameter affecting facemask protection.
口罩被广泛用作公众的一种防护措施，以防止吸入包括季节性、猪和其他形式的流感和严重急性呼吸系统综合征（SARS）等空气传播的病原体。然而，有关口罩在减少社区感染方面的有效性的科学数据极其有限，甚至相互矛盾。在这项工作中，使用两个标记为“源”和“易感”的人体模型来测量口罩在各种排放情况下提供的保护。源被修改以产生多分散的超细颗粒，而易感被修改以模拟真实的呼吸模式。口罩受到呼气过程中产生的伪稳态和高度瞬态排放的挑战，其中参数（例如人体模型之间的距离、排放速度和呼气持续时间）得到了系统的控制和测量。还研究了四种不同类型的口罩贴合度的性能，从理想贴合到正常佩戴实践。在准稳态浓度环境下，口罩的保护作用为 45%，而在呼气排放下，保护作用在 33%至 100%之间变化。还观察到，源和人体模型之间的距离是影响口罩保护作用的最具影响力的参数。
