The lack of quantitative risk assessment of airborne transmission of COVID-19 under practical settings leads to large uncertainties and inconsistencies in our preventive measures. Combining in situ measurements and computational fluid dynamics simulations, we quantify the exhaled particles from normal respiratory behaviors and their transport under elevator, small classroom, and supermarket settings to evaluate the risk of inhaling potentially virus-containing particles. Our results show that the design of ventilation is critical for reducing the risk of particle encounters. Inappropriate design can significantly limit the efficiency of particle removal, create local hot spots with orders of magnitude higher risks, and enhance particle deposition causing surface contamination. Additionally, our measurements reveal the presence of a substantial fraction of faceted particles from normal breathing and its strong correlation with breathing depth.

中文翻译：

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不同实际环境下无症状个体通过空气传播 COVID-19 的风险评估

在实际环境中缺乏对 COVID-19 空气传播的定量风险评估导致我们的预防措施存在很大的不确定性和不一致。结合原位测量和计算流体动力学模拟，我们量化了正常呼吸行为中呼出的颗粒及其在电梯、小教室和超市环境下的运输，以评估吸入潜在含病毒颗粒的风险。我们的结果表明，通风设计对于降低遇到颗粒的风险至关重要。不适当的设计会显着限制颗粒去除的效率，产生具有数量级更高风险的局部热点，并增强导致表面污染的颗粒沉积。此外，