Early in the COVID-19 pandemic health officials resisted the idea that the novel coronavirus was transmissible through tiny aerosol droplets rather than larger, non-buoyant droplets. One case that made headlines and helped shift opinion was that of an outbreak among patrons of a Guangzhou restaurant traced to a single, pre-symptomatic patient zero. The pattern of who became sick at the carrier’s table and those nearby made little sense unless the restaurant’s air flow played a role in spreading the virus.
This paper studies the incident in detail, using an in-house computational fluid dynamics (CFD) code to simulate both airflow in the restaurant and the paths aerosol droplets would follow in that environment. It takes into account flow from the air conditioner and the warm air rising from customers. The study’s predictions of which areas would have the highest concentrations of virus-laden aerosols matches well with the actual pattern of the outbreak. The authors hope that tools like theirs can help prevent future outbreaks by indicating the most dangerous paths for transmission and measures that can block those. (Image credit: Center for Disease Control; video, research, and submission credit: H. Liu et al.)