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Why do I get gassy when I fly?

Why is this happening to me?
Why is this happening to me?
© g-stockstudio/iStockphoto

It forced Washington, D.C.,-to-Dallas American Airlines flight 1053 to make an emergency landing in Nashville in December 2006: the dreaded in-flight fart [source: Shu].

Only 16 percent of American adults admit they toot their own horn while taking public transportation, although surely the other 84 percent just don't admit to it [source: Lindenbaum]. When we're flying, we're prone to a phenomenon called jet bloat — and yes, like jet lag, it's a real thing. More than 60 percent of pilots report they experience regular jet bloat [source: Robson]. And that distended, gassy feeling can only mean one thing: high-altitude, in-flight flatulence.

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The average person can expect to pass about 1 liter (or a quart) of gas, which adds up to no fewer than 10 farts within 24 hours (and if you hold those farts in during the day, expect that gas to escape while you sleep) [source: Robson]. Fart composition varies from person to person, but it generally breaks down as 59 percent nitrogen, 21 percent hydrogen, 9 percent carbon dioxide, 7 percent methane and 4 percent oxygen. It's the remaining small percentage — less than 1 percent — of sulfur-containing gasses (including hydrogen sulfide) that gives farts their distinctive odors. And all that's needed to make that fart smellable is 1 part per 100 million parts air [source: Goldberg and Leyner].

It's not only the farts of those in the immediate vicinity that linger in the cabin; a single fart can reach speeds of up to 10 feet per second [source: Cohen]. Additionally, half of the cabin air is recirculated air — which means each fart's odor is circulating throughout the plane.

If you've ever noticed that the plastic water bottles you bring with you on your flights get a little crunched between takeoff and landing, then you already guess the answer to why we get gassy when we fly. It's all about pressure.

While we typically fly at altitudes between 33,000 to 45,000 feet (10,058 to 13,716 meters), inside the cabin it feels to us as though we're only between 6,000 and 8,000 feet (1,829 and 2,438 meters) above sea level. On the ground, the human body is accustomed to an atmospheric pressure of 760 millimeters of mercury (mmHg), but when we fly that pressure decreases to about 565 mmHg. When altitude increases, pressure decreases; when the pressure drops, volume increases.

This is the thermodynamic principle called the ideal gas law: PV=nRT, where P is the pressure of the gas, V is the volume of the gas, n is the amount of gas, R is the ideal gas constant and T is the temperature of the gas.

When the atmospheric pressure in the plane's cabin drops, the air inside your body needs more space, and the volume of gas expands — by roughly 25 percent. The greater volume of intestinal gas equals a greater number of farts and, perhaps, a couple temporary inches of bloat around your abdomen [source: Cox].

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Everyone just sit back, relax … and let it go.
Everyone just sit back, relax … and let it go.
© Pietro_Ballardini/iStockphoto

Although there isn't much you can do about the change in pressure from being on the ground to the change of pressure we experience when you fly, there are some coping strategies you can try to help minimize the amount of gas building up in your gastrointestinal tract. The secret? Well, first, stop swallowing so much air.

It's true, you swallow air as you eat, drink and talk. And, that gum you chew to help pop your ears during takeoff and landing may relieve the pressure in your middle ear, but you pay for it in air biscuits. Even the anxiety of flying can make you swallow more air, although you probably won't notice until you're hit with the social anxiety of whether you'll be able to hold it in.

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While 20 percent of your intestinal gas comes from the air you swallow, 80 percent comes from the foods you eat [source: Escherich and McCarthy]. Airport dining may offer better options — or, depending on the airport, at least more options — than in-flight offerings. But regardless of where you grab a bite the day before and the day of travel, there are some foods, healthy and unhealthy alike, that are just more associated with bloating and stink bombs than others. Some fruits and vegetables may be difficult to digest, including the well-known fart-producers beans, cabbage and broccoli. Dairy and wheat may also cause bloating and gassiness, if you're sensitive to lactose or gluten. Yes, cheese, in fact, can be blamed for our cutting the cheese. Fried and spicy foods also bring on the bloat.

It also pays off to pay attention to what you choose from the beverage service. Carbonated beverages — including beer and soda — are pretty self-explanatory gas producers. It's carbon dioxide gas that makes carbonated drinks fizzy. Artificial sweeteners also contribute to jet bloat and increased gas problems because we're unable to digest them well (or at all).

For most of us, keeping intestinal gas in won't cause any problems other than discomforts such as bloating, indigestion and heartburn, but it's better to let it out. Well, at least for you it is; your travel companions may think otherwise. But they're probably farting, too.

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Author's Note: Why do I get gassy when I fly?

Before I did this research I knew two dumb jokes, and now I know three. What do you call a person who doesn't fart in public? A private tutor.

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More Great Links

Sources

  • Cohen, Ian. "The Anatomy of a Fart." Muscle & Fitness. (June 26, 2015) http://www.muscleandfitness.com/features/edge/anatomy-fart
  • Cox, John. "Ask the Captain: How high can a plan fly?" USA Today. Feb. 2, 2014. (June 25, 2015) http://www.usatoday.com/story/travel/columnist/cox/2014/02/02/maximum-altitude-airlines-concorde/5165635/
  • Escherich, Katie and Kate McCarthy. "Simple Ways to Battle Bloating." ABC News: Good Morning America. Oct. 19, 2009. (June 25, 2015) http://abcnews.go.com/GMA/OnCall/dr-mehmet-oz-tips-avoid-bloating/story?id=8858561
  • Goldberg, Billy and Mark Leyner. "The Body Odd: Passing Time by Passing Gas, Plus Fun Fart Facts!" NBC News. March 19, 2008. (June 25, 2015) http://bodyodd.nbcnews.com/_news/2008/03/19/4380042-passing-time-by-passing-gas-plus-fun-fart-facts
  • Jaret, Peter. "Bloating 101: Why You Feel Bloated." WebMD. Sept. 10, 2011. (June 25, 2015) http://www.webmd.com/digestive-disorders/diarrhea-10/bloated-bloating
  • Lindenbaum, Laurie. "'Jet Bloat' a Common Side Effect of Air Travel." CharcoCaps. April 10, 2009. (Jun 25, 2015) http://www.prweb.com/releases/2009/04/prweb2307844.htm
  • Pommergaard, Hans C. et al. "Flatulence on Airplanes: Just Let it Go." The New Zealand Medical Journal. Vol. 126, No. 1369. Feb. 15, 2013. (June 25, 2015) https://www.nzma.org.nz/journal/read-the-journal/all-issues/2010-2019/2013/vol-126-no-1369/view-pommergaard
  • Popken, Ben. "Let Your Flatulence Fly, Scientists Urge Passengers." NBC News. Feb. 20, 2013. (June 25, 2015) http://www.nbcnews.com/business/travel/let-your-flatulence-fly-scientists-urge-passengers-f1C8431651
  • Robson, David. "How to Tackle the Most Embarrassing Problem on Planes." BBC. Dec. 21, 2014. (June 25, 2015) http://www.bbc.com/future/story/20141218-why-do-we-fart-more-on-planes
  • Shu, Samuel. "Flatulence Leads to Flight Diversion." USA Today. Dec. 6, 2006. (June 25, 2015) http://usatoday30.usatoday.com/travel/flights/2006-12-05-flatulence-landing_x.htm

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