Efficacy of ventilation strategies and plastic partitions in mitigating the spread of aerosols in indoor spaces

During the COVID-19 pandemic, protective physical barriers and ventilation strategies, were used to prevent the rapid multi-directional exchange of bio-aerosols that occur when people interact in close proximity. Physical barriers provided a cheap solution that was rolled out in many spaces, yet there is little definitive proof of their impact on aerosol transport and infection risk. This study considers the impact of ventilation (no ventilation/5 air changes per hour(ac/h)), air movement strategies (mixing/no mixing) and room partitions (50 cm2, 125 cm2, 210 cm2) on aerosol concentration, size distribution, and deposition. The results show 5 ac/h leads to a reduction in all particle sizes, ranging from a 20 % reduction for 0.3 µm particles to 38 % for 3 µm particle counts. The addition of air mixing to 5 ac/h resulted in higher reductions (from 38 % for 0.3 µm to 88 % in 3 µm) when compared to no ventilation. In the absence of ventilation, the small partition had the greatest impact on aerosol reductions, from 7 % for 0.3 µm to 33 % for 3 µm. At 5 ac/h, the large partition was most effective with reductions ranging from 30 % for 0.3 µm to 24 % for 3 µm aerosols. Once air mixing was introduced, the impact of partitions was minimised due to air homogenisation. The results suggest good ventilation outweighs the impact of partitions in indoor spaces, however in the absence of ventilation, small and large partitions reduce aerosol numbers and subsequently transmission risk.