Inhaled viral droplets may immediately be expelled and cause an escalating re-transmission. Differences in the deposition location of inhaled viral droplets may have a direct impact on the probability of virus expelling. This study develops a numerical model to estimate the region-specific deposition fractions for inhalable droplets (1-50 μ m) in respiratory airways. The results identified a higher deposition fraction in the upper airways than the lower airways. Particularly for droplets larger than 10 μ m, the relatively high deposition fraction in the oral/laryngeal combined region warns of its easy transmission through casual talking/coughing. Moreover, considering droplet sizes’ effect on virus loading capacity, we built a correlation model to quantify the potential of virus expelling hazards, which suggests an amplified cascade effect on virus transmission on top of the existing transmission mechanism. It therefore highlights the importance of considering the instant expelling possibilities from inhaled droplets, and also implies potentials in restricting a rapid secondary transmission by measures that can lower down droplet deposition in the upper airways.

中文翻译：

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吸入病毒飞沫的沉积特征可能导致 COVID-19 的快速二次传播

吸入的病毒液滴可能会立即被排出并导致不断升级的重新传播。吸入病毒液滴沉积位置的差异可能直接影响病毒排出的概率。本研究开发了一个数值模型来估计呼吸道中可吸入液滴 (1-50 μ m) 的特定区域沉积分数。结果发现上呼吸道的沉积分数高于下呼吸道。特别是对于大于 10 μ m 的飞沫，口腔/喉部结合区域相对较高的沉积分数警告说它很容易通过随意的谈话/咳嗽传播。此外，考虑到液滴大小对病毒载量的影响，我们建立了一个相关模型来量化病毒排出危害的潜力，这表明在现有传播机制之上对病毒传播的放大级联效应。因此，它强调了考虑从吸入的飞沫中即时排出的可能性的重要性，也暗示了通过降低上呼吸道飞沫沉积的措施来限制快速二次传播的可能性。