Ew! WHAT Happens When You Sneeze?Here's some incentive to cover your mouth the next time you sneeze! A little "achoo" launches a sheet of fluid that balloons, then breaks apart in long filaments that destabilize and finally disperses as a spray of droplets, similar to paint that is flung through the air.
That's the word from MIT researchers who used high-speed videos to show that a little sneeze results in more than a simple spray into the air. Instead it produces a complex fluid cascade that can easily spread cold germs.
Using two high-speed cameras, the researchers recorded more than 100 sneezes from healthy human subjects and captured the fraction of a second during which fluid is expelled from the mouth and flung through the air. Almost every sneeze produced the same paint-like pattern of fluid fragmentation with slight variations: The more elastic the fluid, or saliva, the longer the fluid traveled before breaking into droplets.
This complex pattern of fluid breakup runs counter to what most people expect, which is that a sneeze produces a simple and uniform spray of droplets.
"It's important to understand how the process of fluid breakup, or fluid fragmentation, happens," says Lydia Bourouiba, who runs MIT's Fluid Dynamics of Disease Transmission Laboratory. "What is the physics of the breakup telling us in terms of droplet size distribution and the resulting prediction of the downstream range of contamination?"
Bourouiba says understanding how sneezing disperses droplets can help researchers map the spread of infections through the environment, as well as identify individuals who may be "super-spreaders."
The takeaway: Use a tissue!
The study findings were published in the journal Experimental Fluids.