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Ah-ah- achoo! Does that sneeze mean swine flu?

By Diane Mapes

We do it when we’re sick, when we’re cleaning out our closets and, according to a recent YouTube chat with astronaut David Wolf, we do it in space. Even pandas do it.

Yet few really understand what’s happening when our noses explode in a sneeze. As we head into cold season and the dreaded return of swine flu, even the most innocent sneeze (Do you have a cat?!) can spread paranoia. Let go with a noisy honk and watch the uncomfortable reaction, or downright hostile stares, of nearby strangers. But are those powerful sneezes —  called sternutations — proof that we’re carrying some kind of virus? Why do we sneeze anyway?

According to Dr. Anne Maitland, assistant professor of clinical immunology at Mount Sinai School of Medicine in New York City, sneezing is an involuntary response to anything the body identifies as a nasal irritant, including dust, hair spray, cigarette smoke, perfume, cleaning chemicals, pollen and/or viral inflammation.

“There are nerve fibers as well as hairs in your nasal passages that send a signal when they’re irritated,” she says. “They’ll signal: ‘We’re seeing something we don’t like. Mobilize forces quickly.’”

The body then goes into reflex mode, taking in air (“Aaaah, aaaah, aaaah”), closing your eyes and shutting the glottis, the membrane that covers the tube that leads to your stomach. Once all that’s done, air will rush up from your lungs and go through your mouth and nose at what Maitland calls “tremendous speed.”

“It’s a really forceful ejection, like taking a power washer to blow out your nose,” she says. “It’s trying to expel anything that’s not supposed to be there.”

Unfortunately, sneezes can sometimes expel that thing onto others.

“If you’ve seen somebody cough, the propellants from that will travel far,” says Maitland. “But sneeze propellants will go further. They’ve been clocked anywhere from 80 to 800 miles per hour. They travel almost 75 percent the speed of sound.”

Talk about a clear-out.

While getting sprayed with a sneeze is no picnic, it’s not cause for concern if the person is simply suffering from allergies — which aren’t contagious — or sneezing in response to dust, pepper or other nasal irritants.

If the person has cold or flu symptoms, however, such as fever or muscle aches, then those in the line of fire could be in danger of picking up more than just a gentle misting. When do you know it’s a cold and not allergies?

“It’s always the presence of other symptoms,” says Maitland. So if the person is also shivering or seems to have a fever or complains of being achy, run away.  “Also, with allergies, you can predict it. It happens at a certain time of year or whenever you go visit Aunt Tillie and her five cats,” says Maitland.

Rhinoviruses are fairly hearty and can last for hours on surfaces, Maitland warns, so it’s important to wash your hands, especially during cold and flu season. 

However,  not all sneezes are caused by common culprits like allergies, irritants and cold or flu viruses.

Sneezing can also be triggered by environmental factors such as cold and dry air, by hormones, by certain kinds of drugs and by stimulation of the cranial trigeminal nerve, which often happens when you tweeze your eyebrows, according to a recent study. “If you tug on your eyebrows you’re irritating the hard wiring that’s responsible for causing the sneeze in the first place,” says Maitland. “You’ve inadvertently accessed that pathway.”

There’s also the “photic sneeze reflex” which causes anywhere from 18 percent to 35 percent of the world’s population to sneeze whenever they look at the sun or any bright light.

“We do not know exactly why this happens, but it might reflect a ‘crossing’ of pathways in the brain between the papillary light reflex arc and the sneezing reflex arc,” writes Murat Songu in the journal. “The reflex can be triggered only after the first exposure to light, never on repetitive stimulation.”

As with hiccups, some individuals have been overwhelmed with uncontrollable or “intractable sneezing,” such as the 13-year-old girl who, in 1957, sneezed steadily for over two months. Then there’s the teenage boy, written about in a 1994 case study, who sneezed continually for over a year. According to one study, most cases of intractable sneezing involve adolescents and are psychological in origin.

“It’s like people who have a tic with coughing,” says Maitland. “Some people have psychological disorders that are associated with intractable sneezing.”

Considering how satisfying a good sneeze can feel, it’s not too surprising the reflex has also been associated with sex. In 1972, researchers wrote about a 69-year-old man who complained of severe sneezing immediately following orgasm and a 2008 case study involved a middle-aged man with uncontrollable fits of sneezing that occurred along with sexual thoughts. Curious about the frequency with which this happened, researchers tapped into several online chat rooms and found “17 people of both sexes reporting sneezing immediately upon sexual ideation and three people after orgasm.” 

“There are also some people who orgasm when they sneeze,” says Maitland. “These people feel really good” after a sneeze, says Maitland. “That’s just how they’re wired.”