Numerical evaluation of space form design for outpatient waiting space to reduce airborne infection risk in hospitals

The outpatient waiting space (OWS), with high density and frequent variations of occupants, represents a high-risk space for the spread of respiratory infectious diseases (RIDs) in hospitals. While previous studies have proposed strategies related to occupant behavior and environmental quality, there is a limited exploration of the impact of space form design on infection risk in OWSs. This study developed a numerical method for assessing the airborne infection risk, considering the non-uniform distribution of infectious particles and variations in occupant distributions. Validated computational fluid dynamics (CFD) simulations were employed to calculate the particle distributions. The intake fraction, accumulated throughout the waiting process, was then integrated into the Wells-Riley model for risk evaluation. Using the typical ventilation form of ceiling supply and ceiling return, with an air change per hour (ACH) set to 6 h−1 as the baseline, 12 typical space forms, including four space shapes (L shape, T shape, U shape, and O shape) and three entrance layouts (single-side entrance, middle entrance, and double-side entrances), were selected for comparisons. The results showed significant variations in infectious particle distributions across the 12 space forms, with average infection probabilities (IPs) ranging from 3.47 % to 19.75 %, suggesting that appropriate space form design has the potential to reduce IP by 16.28 %. These findings offer a novel perspective on mitigating airborne infection risk in hospitals by emphasizing the significance of architectural design. Moreover, precise space design guidance is proposed for OWS to safeguard human health against the spread of RIDs.