Data from: Should we use ceiling fans indoors to reduce the risk of transmission of infectious aerosols?

The effects of ceiling fans on the transmission of infectious aerosols
remain poorly understood, leading to conflicting recommendations. We
conducted repeated experiments in a well-controlled chamber with a typical
mixing ventilation system at three different ventilation rates with and
without ceiling fans. We evaluated airborne infection risks for short- and
long-range transmission routes based on size-resolved tracer particles
measured at various locations. We found that the mixing ventilation
without fans only effectively diluted the airborne particle concentration
for the long-range route but not for the short-range. By using ceiling
fans to enhance air mixing, tracer particles were distributed more
homogeneously throughout the room, leading to up to 77% reduction in
short-range particle exposure while a slight increase of less than 14% in
long-range exposure. Based on the dilution-based Wells-Riley model, the
changes in particle concentration translated to a maximum 47% reduction in
short-range infection risk and a marginal 4% increase for long-range
transmission. Based on the dilution factors obtained from the experiments,
we developed a decision-making tool that uses the ventilation rate, the
number of individuals at short- and long-range, and the disease's
transmissibility to decide whether the use of ceiling fans is beneficial.
Deploying ceiling fans always reduces the concentration of particles in
the short range and, assuming a relationship between particles and
pathogens, this directly translates to a diminished short-range risk.
Based on the modeling of the overall risk, the benefits of fans are
highest when the room is ventilated according to code, when masking
measures are in place, and when the pathogen is not highly contagious.

吊扇对感染性气溶胶（infectious aerosols）传播的影响目前仍未得到充分阐明，由此导致相关防控建议存在分歧。本研究在一间配备典型混合通风系统（mixing ventilation system）的受控实验舱内开展了多组重复实验，设置三种不同通风速率工况，分别开展开启与未开启吊扇的对照实验。本研究基于在多个测点采集的粒径解析示踪粒子数据，评估了短程与远程传播路径下的空气传播感染风险。研究结果显示，未开启吊扇的混合通风系统仅能对远程传播路径的空气颗粒物浓度实现有效稀释，对短程路径则无显著效果。通过启用吊扇强化室内空气混合，示踪粒子在室内的分布均匀性显著提升，可使短程颗粒物暴露量最高降低77%，但远程暴露量仅出现不足14%的小幅上升。基于稀释法的威尔斯-莱利（Wells-Riley）模型，颗粒物浓度的变化对应短程感染风险最高可降低47%，而远程传播风险仅出现4%的小幅上升。基于实验得到的稀释因子，本研究开发了一款决策工具，可通过通风速率、短程与远程暴露人数以及疾病传播能力，判断启用吊扇是否具有应用收益。启用吊扇始终可降低短程范围内的颗粒物浓度，若假设颗粒物浓度与病原体载量存在关联，则可直接转化为短程感染风险的降低。基于整体感染风险的建模结果，当房间按照规范通风、人员佩戴口罩且病原体传染性较弱时，启用吊扇的收益最为显著。