COVER YOUR MOUTH, YOU FILTHY ANIMAL

Here for sharing far and wide is an animation that shows just how propulsive (repulsive?) a sneeze can be.

The footage was acquired by MIT researchers Lydia Bourouiba and John Bush. The pair collaborated with Eline Dehandschoewercker, a graduate student at ESPCI ParisTech, and used high speed imaging, lab simulations and mathematical models to create a new analysis of coughs and sneezes from a fluid-mechanics perspective.

Their findings (published under the excellent title "Violent expiratory events: on coughing and sneezing" in the Journal of Fluid Mechanics) indicate that the droplets emitted during a sneeze can travel on a "multiphase turbulent buoyant cloud" (that's fancy talk for a cough or sneeze) up to 200-times farther than previously believed. Surprisingly, it's the littlest droplets that appear to travel farthest:

"If you ignored the presence of the gas cloud, your first guess would be that larger drops go farther than the smaller ones, and travel at most a couple of meters," Bush says. "But by elucidating the dynamics of the gas cloud, we have shown that there's a circulation within the cloud — the smaller drops can be swept around and resuspended by the eddies within a cloud, and so settle more slowly. Basically, small drops can be carried a great distance by this gas cloud while the larger drops fall out. So you have a reversal in the dependence of range on size."

[The Journal of Fluid Mechanics via MIT News]