Figure 1. Room ventilation design and experimental set-up.

The isolation room is fitted with the downward ventilation systems. The design is to supply conditioned and clean air from the ceiling diffuser to sweep away contaminants, which would then be removed via the exhaust outlets at the floor level. The Human Patient Simulator was lying at 45° on the bed. The exhaled air plume was marked with intrapulmonary smoke, and was revealed by the laser light sheet. The images were captured by a high-definition camera positioned to the left side of the simulator when examining the cough propagation distances in the median sagittal plane. Smoke concentration in the plume was estimated from the light scattered by smoke particles.