Department of Material Analysis and Indoor Chemistry, Fraunhofer WKI, Braunschweig, Germany.
Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
Indoor Air. 2022 Aug;32(8):e13087. doi: 10.1111/ina.13087.
The SARS-CoV-2 pandemic, which suddenly appeared at the beginning of 2020, revealed our knowledge deficits in terms of ventilation and air pollution control. It took many weeks to realize that aerosols are the main route of transmission. The initial attempt to hold back these aerosols through textile masks seemed almost helpless, although there is sufficient knowledge about the retention capacity of fabric filters for aerosols. In the absence of a sufficient number of permanently installed heating, ventilation, and air conditioning systems, three main approaches are pursued: (a) increasing the air exchange rate by supplying fresh air, (b) using mobile air purifiers, and (c) disinfection by introducing active substances into the room air. This article discusses the feasibility of these different approaches critically. It also provides experimental results of air exchange measurements in a school classroom that is equipped with a built-in fan for supplying fresh air. With such a fan and a window tilted at the appropriate distance, an air exchange rate of 5/h can be set at a low power level and without any significant noise pollution. Heat balance calculations show that no additional heat exchanger is necessary in a normal classroom with outside temperatures above 10°C. Furthermore, a commercial mobile air purifier is studied in a chamber and a test room setup in order to examine and evaluate the efficiency of such devices against viable viruses under controlled and realistic conditions. For this purpose, bacteriophages of the type MS2 are used. Both window ventilation and air purifiers were found to be suitable to reduce the concentration of phages in the room.
2020 年初突然出现的 SARS-CoV-2 大流行，暴露出我们在通风和空气污染控制方面的知识不足。人们花了数周时间才意识到气溶胶是主要的传播途径。最初试图通过纺织口罩来阻挡这些气溶胶的做法似乎几乎毫无作用，尽管我们对织物过滤器对气溶胶的截留能力有足够的了解。在缺乏足够数量的永久性安装的加热、通风和空调系统的情况下，主要有三种方法可以选择：（a）通过供应新鲜空气来增加空气交换率，（b）使用移动空气净化器，（c）通过向室内空气引入活性物质进行消毒。本文批判性地讨论了这些不同方法的可行性。它还提供了在配备内置风扇以供应新鲜空气的学校教室中进行空气交换测量的实验结果。在这样的风扇和倾斜适当距离的窗户的情况下，可以在低功率水平下设置 5/h 的空气交换率，并且没有任何明显的噪音污染。热平衡计算表明，在室外温度高于 10°C 的正常教室中，不需要额外的热交换器。此外，在一个房间和一个测试室中研究了一种商用移动空气净化器，以在受控和现实的条件下检查和评估此类设备对活病毒的效率。为此，使用了 MS2 型噬菌体。研究发现，窗户通风和空气净化器都可以降低室内噬菌体的浓度。
