Health & Medicine

The distance that germs can travel is nothing to sneeze at

Germs from a sneeze can travel 20 feet or more, according to a recent study.
Germs from a sneeze can travel 20 feet or more, according to a recent study. TNS

Sneezes are everywhere these days, during the height of cold and flu season. The chorus of ah-choos in offices, on buses and in homes often sends bystanders scrambling to get out of the line of germ-spreading fire.

But how far is far enough away to avoid getting hit by a snot-and-fluid projectile? A lot farther than you might — or would like to — think. We’re talking 20 feet or more.

Recent research offers new insights on the science of sneezing — revealing what happens when we sneeze and how far the spray of saliva and mucus can travel.

A sneeze is a reflex reaction, said Dr. Scott Davies, a physician at Hennepin County Medical Center in Minneapolis. It happens when receptors in the nose detect irritants. It can be an odor, pollen in the air or pet dander — any type of allergen, really. Once the nose receptors sense the irritant, the brain receives a signal and the body responds involuntarily.

“That reflex triggers a violent reaction that involves your neck, the chest, the abdomen, the diaphragm,” Davies said. “You create this forceful blast of air through your nose.”

The air comes from your lungs, and there’s a deep inhale just before the sneeze to produce a large gust of air.

So what purpose does sneezing serve?

Cleansing, said Jeanne Pfeiffer, an associate professor at the University of Minnesota School of Nursing. Think of it as your body spotting a squatter in the nose that needs to be evicted.

Sneezing helps reset the environment inside the nose, according to a recent study conducted by researchers at the University of Pennsylvania in Philadelphia.

For a long time, people on the front lines of sneeze science thought that the droplets scattered from a sneeze traveled only a short distance, but a slow-motion video of a sneeze captured recently by Massachusetts Institute of Technology researchers uncovered a more troubling truth: Those sneeze particles can go far.

The video shows in gross detail what happens to the liquid mixture spewed from a person’s mouth and nose during a sneeze.

The findings, as described by MIT researchers in the New England Journal of Medicine, show that the droplets spread farther than previously thought — aided by a swirling puff cloud.

“The largest droplets rapidly settle within about 3 to 6 feet away from the person,” wrote researcher Lydia Bourouiba, of MIT’s Fluid Dynamics and Disease Transmission Laboratory. “The smaller and evaporating droplets are trapped in the turbulent puff cloud, remain suspended and, over the course of seconds to a few minutes, can travel the dimensions of a room and land up to 19 to 26 feet away.”