Effect of Air Sampling Location on Monitoring of SARS‐CoV‐2 Viral Aerosol Transmission in an Indoor Space

Sampling viral aerosols in a small volume of liquid is crucial for effectively monitoring the aerosol transmission of viruses. However, the distribution of viral aerosols may fluctuate depending on the airflow. Therefore, sampling location in indoor spaces is crucial because the concentration of viral aerosols may fluctuate. In this study, the effects of sampling location on viral aerosol monitoring in indoor spaces were investigated. This study focused on seven negative‐pressure isolation rooms of the same type for patients with SARS‐CoV‐2 infection where the source of the virus was present. Air sampling was conducted at two positions in each room: 30 cm below the ventilation air outlet (Sampling Position #1) and 80 cm above the floor (Sampling Position #2). The air samples were analyzed using polymerase chain reaction (PCR). The virus was detected at Sampling Position #1, but not at Sampling Position #2. To investigate the propagation of coronaviruses in the air, computational fluid dynamics (CFD) analysis was performed. A Eulerian–Lagrangian model was employed to examine the transport of cough droplets, accounting for their evaporation and dispersion. The CFD analysis revealed that the number of viral particles captured at Sampling Position #1 was about six times greater than that captured at Sampling Position #2. The results of the PCR and CFD analyses show that the proper selection of a sampling location is crucial for the successful monitoring of airborne viruses.