Partition walls as effective protection from bio-aerosols in classrooms - an experimental investigation.

During a pandemic, protective measures to prevent bio-aerosol based infections, such as Corona Virus Infection Disease 19 (COVID 19), are very important. Everyday face masks can only partially block aerosols, and their effectiveness also depend on how well the person is wearing it. They are recommended for classroom situations during high pandemic activity. However, 'unprotected' communication with and among children is fundamental from the pedagogical and psychological point of view for normal psychosocial development and teaching. Partition walls around the persons can theoretically provide substantial standardized mechanical protection against the spread of droplets and aerosols, either as additional protection to face masks or as an alternative. In the present research, the protection effectiveness of partition walls was investigated. With mannequin heads, fog generators, line lasers and a classroom-like setup with protective walls, flow visualization and aerosol concentration measurements were performed. Additionally, an active fan-suction system was tested to remove the channelled aerosols on top of the partition walls before they reach other persons in the room. It was found that partition walls protect neighbours from bio-aerosol contact regardless of whether they wear masks or not. The combination with standardized room ventilation enforces this effect. Moreover, the experiments performed here clearly showed that partition walls may protect neighbours from bio-aerosols better than suboptimally fitting everyday face masks only. Partition walls are the most effective protection against infectious bio-aerosols in classroom settings and should be combined with standardized ventilation as the preferred method for classrooms during the current COVID 19 pandemic.