MIT Scientists Figure Out What Happens When We Sneeze

They map out how mucus and saliva break into droplets
By Elizabeth Armstrong Moore,  Newser Staff
Posted Nov 25, 2015 7:50 AM CST
MIT Scientists Figure Out What Happens When We Sneeze
Screenshot of a video recording a person's sneeze.   (Lydia Bourouiba, Massachusetts Institute of Technology)

A sneeze is not just a sneeze. It is a "high-propulsion" cloud of mucus and saliva that spreads across entire rooms, even reaching ceilings and the ventilation ducts found there, in a matter of minutes. MIT researchers first gained attention last year with these findings, reports CBS Boston, and they're about to release their latest findings in the journal Experiments in Fluids. This time they used two cameras to capture high-speed videos of two healthy people sneezing roughly 50 times over the course of several days. They were looking to gain an understanding of the first stage of the sneeze, "the part that is still a big unknown. ... I wanted to ... go upstream and look at the mouth, at what is coming out," says lead researcher Lydia Bourouiba.

What Bourouiba and her team found was that the droplets don't exit the mouth "already formed and neatly distributed in size," as had long been assumed, she says in a press release. Instead, a "complex cascading breakup" occurs, with the mucus and saliva beginning as a sheet then moving in "bursts, bags, and beaded strings during this progression," as the BBC puts it. Bourouiba calls it a "high-propulsion sneeze cloud." Next the researchers plan to use nine high-speed cameras to map out sneezes in 3D. "We realized that there were very rich three-dimensional dynamics that we really needed to capture," she says, adding that only then will they understand sneezes "in their full glory." (Check out what a sneeze dislodged from this man's nose after 44 years.)

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