Cardno ChemRisk, Chicago, Illinois.
J Occup Environ Hyg. 2022 May;19(5):302-309. doi: 10.1080/15459624.2022.2053692. Epub 2022 Apr 6.
In 2020, many cities closed indoor dining to curb rising COVID-19 cases. While restaurants in warmer climates were able to serve outdoors year-round, restaurants in colder climates adopted various solutions to continually operate throughout the colder months, such as the use of single-party outdoor dining enclosures to allow for the continuation of outdoor dining. This study evaluates indoor air quality and the air exchange rate using carbon dioxide as a tracer gas in a dining enclosure (12.03 m) and models the probability of COVID-19 infection within such an enclosure. The air exchange rates were determined during two trials for the following scenarios: (1) door closed, (2) door opened, and (3) door opened intermittently every 15 min for 1 min per opening. The probability of COVID-19 infection was evaluated for each of these scenarios for 1 hr, with occupancy levels of two, four, and six patrons. The Wells-Riley equation was used to predict the probability of infection inside the dining enclosure. The air exchange rates were lowest in the closed-door scenarios (0.29-0.59 ACH), higher in the intermittent scenarios (2.36-2.49 ACH), and highest in the open-door scenarios (3.61 to 33.35 ACH). As the number of subjects inside the enclosure increased, the carbon dioxide accumulation increased in the closed-door and intermittent scenarios. There was no identifiable accumulation of carbon dioxide in the open-door scenario. The probability of infection (assuming one infected person without a mask) was inversely proportional to the airflow rate, and ranged from 0.0002-0.84 in the open-door scenario, 0.0034-0.94 for the intermittent scenarios, and 0.015-1.0 for the closed-door scenarios. The results from this study indicate that under typical use, the indoor air quality inside dining enclosures degrades during occupancy. The probability of patrons and workers inside dining enclosures being infected with COVID-19 is high when dining or serving a party with an infected person.
2020 年，许多城市关闭了室内餐饮以遏制 COVID-19 病例的上升。虽然较温暖气候地区的餐厅能够全年在户外提供服务，但较寒冷气候地区的餐厅则采用了各种解决方案，以在较冷的月份持续运营，例如使用单人户外用餐围蔽来继续提供户外用餐。本研究使用二氧化碳作为示踪气体评估了用餐围蔽内的室内空气质量和空气交换率，并对围蔽内 COVID-19 感染的概率进行了建模。在以下三种情况下，分别在两次试验中确定了空气交换率：（1）门关闭，（2）门打开，（3）每隔 15 分钟打开一次门，每次开门 1 分钟。在每种情况下，评估了 1 小时内 2、4 和 6 位顾客的感染概率。使用 Wells-Riley 方程预测用餐围蔽内感染的概率。在门关闭的情况下，空气交换率最低（0.29-0.59 ACH），在间歇性情况下较高（2.36-2.49 ACH），在门打开的情况下最高（3.61 到 33.35 ACH）。随着围蔽内人数的增加，在门关闭和间歇性情况下，二氧化碳的积累增加。在门打开的情况下，没有发现二氧化碳的可识别积累。感染的概率（假设一个未戴口罩的感染者）与气流率成反比，在门打开的情况下，范围从 0.0002-0.84，在间歇性情况下，范围从 0.0034-0.94，在门关闭的情况下，范围从 0.015-1.0。本研究的结果表明，在典型使用情况下，用餐围蔽内的室内空气质量在有人占用时会恶化。在围蔽内用餐或服务感染者的情况下，用餐者和工作人员感染 COVID-19 的概率很高。
