We already knew that sneezing is pretty gross, but now researchers have worked out that it is actually much more horrible than previously thought. Alongside giving us new insights into the dynamics of sneezes, the research is important because it helps shed light on disease transmission and could help us develop ways to stop certain illnesses from spreading.
A team of researchers from the Massachusetts Institute of Technology (MIT) used high-speed cameras to capture in detail what happens after a person sneezes. While you may expect a sneeze to produce a uniform cloud of droplets, the distribution pattern of the fluid and potential pathogens appears to be much more complex.
According to the research, when people sneeze they eject fluids in compact sheets that then balloon, breaking apart into long filaments. Only at the end does the fluid disperse in a spray of droplets. The results are published in the journal Experiments in Fluids.
The sequence above shows the evolution of the multiphase turbulence cloud that suspends droplets emitted during a sneeze. Illustrated here are times ranging from 7 to 340 milliseconds after the sneeze began. B. E. Scharfman, A. H. Techet, J. W. M. Bush, L. Bourouiba
"It's important to understand how the process of fluid breakup, or fluid fragmentation, happens," Lydia Bourouiba, the Esther and Harold E. Edgerton assistant professor and head of the Fluid Dynamics of Disease Transmission Laboratory at MIT, said in a statement. "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?"
For the experiment, the researchers induced sneezing in three human subjects and recorded the sneezing event as accurately as they could. The sneeze only lasted for one-fifth of a second. The team analyzed more than 100 sneezes in order to identify a common pattern of ejection. While insightful, it's important to note that the sneezes triggered in this experiment likely differ from those induced by illness, especially in terms of fluid composition.
Although the study may sound a bit disgusting, research such as this is important in understanding the spread of disease and what can be done to predict and prevent airborne diseases.
"The way transmission routes are being quantified even today still rely on the traditional way that has prevailed for hundreds of years, which is talking to people to survey who they talked to, where did they go, et cetera," Bourouiba added. "There are clear limits to the accuracy of the data acquired via this process, and we are trying to have more precise measures of contamination and ranges to root disease control and prevention strategies in the physical sciences."