Sumary of Normal breathing without mask can transport saliva droplets to more than 7 feet:
- Previous work considered aerosol transport after coughing or sneezing, while this study specifically looked at normal human breathing..
- A normal breath produces periodic jet flows that contain saliva droplets, but the velocity at which the jet travels is less than a tenth that of a cough or sneeze..
- The investigators found even normal breathing produces a complex field of vortices that can move saliva droplets away from the person’s mouth..
- Our results show that normal breathing without a facial mask generates periodic trailing jets and leading circular vortex rings that propagate forward and interact with the vortical flow structures produced in prior breathing cycles.”.
- A face mask dissipates the kinetic energy of the jet produced by an exhaled breath, disrupting the vortices and limiting the movement of virus-laden droplets..
- In the case of no mask, they found the saliva droplets near the front of the plume of exhaled breath had partially evaporated, reaching a size of only one-tenth of a micron..
- The use of a mask partially redirects the exhaled breath downward and significantly restricts forward movement of the plume, so the risk of suspended droplets remaining in the air is substantially reduced…