CFD study on performance of portable air cleaner on infection risk and draught rate in care homes

Background: During the COVID-19 pandemic, the elderly population experienced disproportionately high mortality rates, with care homes reporting significantly elevated casualties. Care homes constitute a unique built environment with combined elements of healthcare and residential facilities, yet they remain underexplored in ventilation and infection risk research. Methods: The present study employed computational fluid dynamics (CFD) simulation to investigate the performance of portable air cleaner (PAC) on infection risk and impact on draught rate. Different placements of PAC were investigated to evaluate the impact on infection risk and draught rate. A modified Wells-Riley model was used to evaluate infection risk, and the draught rate was evaluated by using Fanger’s draught rate model. Results: The findings reveal that PAC can reduce infection risk (reduction of 75 %-86 %) and achieve an acceptable draught rate (< 10 %). However, three cases showed that improper PAC placement failed to significantly reduce infection risk. Different placements of PAC resulted in distinct airflow patterns and led to 74 % variation of infection risk, highlighting the importance of strategic deployment. Placing PAC closer to susceptible individuals, such as the elderly, resulted in a low infection risk. Placing PAC in the centre of the room led to the lowest infection risk but impractical due to tripping hazards. Conclusion: The present study demonstrates that the deployment of PAC in care homes can deliver a promising reduction in infection risk with an acceptable draught rate. Placement of PAC requires thorough consideration such as guidance by numerical simulations to deliver intended infection risk reduction without compromising draught rate and practicability.