Short-range bioaerosol deposition and recovery of viable viruses and bacteria on surfaces from a cough and implications for respiratory disease transmission

Abstract

Knowledge of respiratory bacterium/virus distribution on surfaces is critical for studying disease transmission via the contact route. Here, we investigated the bioaerosol deposition and distribution on a surface from a cough experimentally. A cough generator was used to release bacterium/virus-laden droplets. A solid surface was placed in front of the cough generator at different relative distances (D = 0.2, 0.5, 0.8, and 1.1 m) and angles (θ=30°, 60°, and 90°). Benign bacteria and bacteriophages were used separately. Results showed that droplet jet directly impinged upon the surface and then spread out along the surface. The distributions of droplet volume and viable microorganisms along the surface were unimodal. We then identified the impaction region based on the droplet flow field from a particle imaging velocimetry technique, which corresponded with the peak position and high-volume area. The impaction region contained around 83% of droplet volume along the vertical axis of the surface. The peak position, peak value, and width of the impaction region were related to D and θ. The micro-organisms inside the droplets did not affect the droplet distribution on near surfaces. The front surface can work as a partition to block the cough jet and protect people behind, and can be smaller when it is installed closer to the coughing person. This work demonstrates a methodology to obtain distribution and viability of microorganism deposited on surface, and suggest guidelines to setting up a protective partition as a possible intervention method against disease transmission.