Environmental Health Department, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA.
Architectural Engineering Department, Pennsylvania State University, University Park, PA 16802, USA.
Environ Sci Process Impacts. 2024 Sep 18;26(9):1476-1488. doi: 10.1039/d4em00114a.
The utilization of portable air cleaners (PACs) is a recommended supplemental approach to help remove airborne pathogens and mitigate disease transmission in learning environments. To improve PAC effectiveness, science-based information is needed to optimize their implementation strategies such as the deployment location, height, and number of PACs. In this study, we developed a Computational Fluid Dynamics (CFD) model to assess how PACs perform in occupied classrooms equipped with displacement and mixing ventilation systems. The results show that PACs with a flow rate of 2.6 h reduce the mean aerosol intake of all students by up to 66%. A key benefit of using PACs is to facilitate air mixing and movement in indoor environments with inadequate ventilation, thereby effectively reducing high aerosol concentrations near the infector. Furthermore, our results highlight the impact of PAC location on its performance. PACs achieve the best effectiveness when placed closed to the infector (within a distance <3 m). In the absence of knowing who is infected, deploying a PAC at the center of the room is recommended. Moreover, adjusting PAC flow discharge height to the breathing height of occupants (, 0.9-1.2 m for seated people) can enhance their effectiveness in spaces with poor air mixing.
便携式空气净化器（PACs）的使用是一种推荐的补充方法，有助于去除空气中的病原体，并减轻学习环境中的疾病传播。为了提高 PAC 的有效性，需要基于科学的信息来优化其实施策略，例如 PAC 的部署位置、高度和数量。在这项研究中，我们开发了计算流体动力学（CFD）模型来评估 PAC 在配备有置换通风和混合通风系统的有人占用的教室中的性能。结果表明，气流速率为 2.6 h 的 PAC 可将所有学生的平均气溶胶吸入量降低多达 66%。使用 PAC 的一个主要好处是可以促进通风不足的室内环境中的空气混合和流动，从而有效降低感染者附近的高气溶胶浓度。此外，我们的结果强调了 PAC 位置对其性能的影响。当 PAC 放置在靠近感染者的位置（距离感染者<3 米）时，其效果最佳。在不知道谁被感染的情况下，建议在房间中心部署一个 PAC。此外，将 PAC 气流排放高度调整到居住者的呼吸高度（对于坐姿者为 0.9-1.2 米）可以增强其在空气混合不良的空间中的效果。
