Effect of ventilation mode and rate on airborne transmission of respiratory disease in indoor environments

Abstract

Ventilation might play an important role in airborne transmission. By using the computational fluid dynamics (CFD) method, ventilation modes, ventilation rates, and infection source's face direction were considered in a multi-person indoor environment (10 m∗10 m∗3 m). The airflow patterns, virus concentration distribution, and infection probability were studied. The results showed that the virus concentration was lower with displacement ventilation (DV, lower in, upper out) than mixing ventilation (MV, top-centre in, upper out) or natural ventilation (NV, upper in, upper out). In 2 air changes per hour (ACH), the infection risk of susceptible persons in MV and NV might be about 2.43-fold and 1.30-fold more than that in DV. Increased ventilation usually reduces viral concentrations and the risk of infection. For the height of breathing zones, the average virus concentration at 12ACH was 49.78%-78.72% lower than that at 2ACH. For susceptible persons at a distance of about 2.8-4.2 m to a COVID-19 infector with 30 min exposure time, the long-range airborne infection probability might be 11.53% (±5.86) (2ACH), 4.96% (±1.82%) (6ACH), and 2.96% (±1.91%) (12ACH).