# Everything you need t know about the science of a "fart"



## syscom3 (Mar 9, 2008)

*Where does fart gas come from?*
The gas in our intestines comes from several sources: air we swallow, gas seeping into our intestines from our blood, gas produced by chemical reactions in our guts, and gas produced by bacteria living in our guts.

*What is fart gas made of?*
The composition of fart gas is highly variable.
Most of the air we swallow, especially the oxygen component, is absorbed by the body before the gas gets into the intestines. By the time the air reaches the large intestine, most of what is left is nitrogen. Chemical reactions between stomach acid and intestinal fluids may produce carbon dioxide, which is also a component of air and a product of bacterial action. Bacteria also produce hydrogen and methane.
But the relative proportions of these gases that emerge from our anal opening depend on several factors: what we ate, how much air we swallowed, what kinds of bacteria we have in our intestines, and how long we hold in the fart.
The longer a fart is held in, the larger the proportion of inert nitrogen it contains, because the other gases tend to be absorbed into the bloodstream through the walls of the intestine.
A nervous person who swallows a lot of air and who moves stuff through his digestive system rapidly may have a lot of oxygen in his farts, because his body didn't have time to absorb the oxygen.
According to Dr. James L. A. Roth, the author of Gastrointestinal Gas (Ch. 17 in Gastroenterology, v. 4, 1976) most people (2/3 of adults) pass farts that contain no methane. If both parents are methane producers, their children have a 95% chance of being producers as well. The reason for this is apparently unknown. Some researchers suspect a genetic influence, whereas others think the ability is due to environmental factors. However, all methane in any farts comes from bacterial action and not from human cells.

*What makes farts stink?*
The odor of farts comes from small amounts of hydrogen sulfide gas and mercaptans in the mixture. These compounds contain sulfur. Nitrogen-rich compounds such as skatole and indole also add to the stench of farts. The more sulfur-rich your diet, the more sulfides and mercaptans will be produced by the bacteria in your guts, and the more your farts will stink. Foods such as cauliflower, eggs and meat are notorious for producing smelly farts, whereas beans produce large amounts of not particularly stinky farts.

*Why do farts make noise?*
The sounds are produced by vibrations of the anal opening. Sounds depend on the velocity of expulsion of the gas and the tightness of the sphincter muscles of the anus. Contrary to a popular misconception, fart noise is not generated by the flapping of the butt cheeks. You can see proof of this in the close-up video footage of Carl Plant's fart on Mate-in-a-State .

*Why are stinky farts generally warmer and quieter than regular farts?*
Most fart gas comes from swallowed air and consists largely of nitrogen and carbon dioxide, the oxygen having been absorbed by the time it reaches the anal opening. These gases are odorless, although they often pick up other (and more odiferous) components on the way through the bowel. They emerge from the anus in fairly large bubbles at body temperature. A person can often achieve a good sound with these voluminous farts, but they are commonly (but not always!) mundane with respect to odor, and don't feel particularly warm.
Another major source of fart gas is bacterial action. Bacterial fermentation and digestion processes produce heat as a byproduct as well as various pungent gases. The resulting bubbles of gas tend to be small, hot, and concentrated with stinky bacterial metabolic products. These emerge as the notorious, warm, SBD (Silent-But-Deadly), often in amounts too small to produce a good sound, but excelling in stench.

*How much gas does a normal person pass per day?*
On average, a person produces about half a liter of fart gas per day, distributed over an average of about fourteen daily farts.
Whereas it may be difficult for you to determine your daily flatus volume, you can certainly keep track of your daily numerical fart count. You might try this as a science fair project: Keep a journal of everything you eat and a count of your farts. You might make a note of the potency of their odor as well. See if you can discover a relationship between what you eat, how much you fart, and how much they smell.

*How does a fart travel to the anus?*
One may wonder why fart gas travels downward toward the anus when gas has a lower density than liquids and solids, and should therefore travel upwards.
The intestine squeezes its contents toward the anus in a series of contractions, a process called peristalsis. The process is stimulated by eating, which is why we often need to poop and fart right after a meal. Peristalsis creates a zone of high pressure, forcing all intestinal contents, gas included, to move towards a region of lower pressure, which is toward the anus. Gas is more mobile than other components, and small bubbles coalesce to from larger bubbles en route to the exit. When peristalsis is not active, gas bubbles may begin to percolate upwards again, but they won't get very far due to the complicated and convoluted shape of the intestine. Furthermore, the anus is neither up nor down when a person is lying down.

*Why do farts come out of your butt?*
The butt is the location of the anus in humans, and by definition, a fart is an anal escape of intestinal gas. We should be grateful that we are not crinoids. The crinoid is a marine creature with a U-shaped gut, and its anus is located next to its mouth.

*How long does it take fart gas to travel to someone else's nose?*
Fart travel time depends on atmospheric conditions such as humidity, temperature and wind speed and direction, the molecular weight of the fart particles, and the distance between the fart transmitter and the fart receiver. Farts also disperse (spread out) as they leave the source, and their potency diminishes with dilution. Generally, if the fart is not detected within a few seconds, it will be too dilute for perception and will be lost into the atmosphere forever.
Exceptional conditions exist when the fart is released into a small enclosed area such as an elevator, a small room, or a car. These conditions limit the amount of dilution possible, and the fart may remain in a smellable concentration for a long period of time, until it condenses on the walls.

*Why is there a 13 to 20 second delay between farting and the time it starts to smell?*
Actually, the fart stinks immediately upon emergence, but it takes several seconds for the odor to travel to the farter's nostrils. If farts could travel at the speed of sound, we would smell them almost instantly, at the same time we hear them.

*Is it true that some people never fart?*
No, not if they're alive. People even fart shortly after death.

*Do even movie stars fart?*
Yes, of course. So do grandmothers, priests, kings, presidents, opera singers, beauty queens, and nuns. Even Yoda farts. See the Britney Smears music video "Oops, I farted again."

*Do men fart more than women?*
No, women fart just as much as men. It's just that most men take more pride in it than most women. There is a large variation among individuals in the amount of fart gas produced per day, but the variation does not correlate with gender.

*I have read that men fart more often than women. If this is true, then women must be saving it up and expelling more gas per fart than men do.
Do men's farts smell worse than women's farts?*
Based on what I have experienced of women's farts, all I can say is that I hope not. Scientific studies of farts show that women's farts have a higher concentration of odor-causing gases than men's farts, but men's farts have a larger volume. The two factors equalize out (the same number of stench molecules for both), so the odor is about the same.


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## Njaco (Mar 9, 2008)

.


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## evangilder (Mar 10, 2008)

Wait, I thought farts stunk so deaf people could enjoy them too...


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## evangilder (Mar 10, 2008)

Oh, and one of the children's books we bought for our son is T_he Gas We Pass: The Story of Farts_ 





Amazon.com: The Gas We Pass: The Story of Farts (My Body Science) (My Body Science): Shinta Cho,Amanda Mayer Stinchecum: Books


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## syscom3 (Mar 10, 2008)

evangilder said:


> Wait, I thought farts stunk so deaf people could enjoy them too...


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## Wayne Little (Mar 10, 2008)

Mmm....you learn something every day!

.....OK who farted!


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## Njaco (Mar 10, 2008)

.


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## Lucky13 (Mar 10, 2008)

I thought that women didn't fart as much as men, because they don't shut up long enough to build up pressure...am I wrong?


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## Njaco (Mar 10, 2008)

If you read, it says its the taking in of air that contributes. So.......


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## syscom3 (Mar 10, 2008)

Theres a joke somewhere about what happens when a woman passes gas with panty hose on.


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## Njaco (Mar 10, 2008)

I see it didn't list the achievments of a fart, such as....

A fart is the sharpest thing in the world.

It goes through a pair of pants without making a hole!


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## ccheese (Mar 10, 2008)

Take it from someone who knows, older women fart more than older men !!
There's nothing that will clear the air like a fart in bed !

Charles


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## Maestro (Mar 10, 2008)

_View: https://www.youtube.com/watch?v=RHcDP_Yew-g_


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## Caity (Mar 25, 2009)

What does this have to do with World War 2 aircraft???????


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## ToughOmbre (Mar 25, 2009)

Caity said:


> What does this have to do with World War 2 aircraft???????



Nothing. That's why this thread is in the *OFF-Topic / Misc.* section.

TO


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## Aaron Brooks Wolters (Mar 25, 2009)

LMAO!!!!!!! We have stooped to an all time low.(still laughing) Way to go syscom, more info than I really needed but I got a good laugh out of it. Thanks.


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## syscom3 (Mar 25, 2009)

Caity said:


> What does this have to do with World War 2 aircraft???????



This has got to be one of the stupidist comments I have read. Look where I posted this under, you dumb#ss!


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## GrauGeist (Mar 25, 2009)

Great info ya' posted Syscom!

And lmao @ "_What does this have to do with World War 2 aircraft???????_"


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## syscom3 (Mar 25, 2009)

GrauGeist said:


> "_What does this have to do with World War 2 aircraft???????_"



I think the AAF had to rethink its menu for aircrews when they started getting the farts at 30,000 feet. Especially for the pilots who were strapped into their seats and couldn't easily lift a leg and let one rip.


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## Glider (Mar 26, 2009)

Way too much information!!

I know Coastal Command had to stop issuing baked beans to their crews as there were a couple of times when a member of the crew was, shall we say, inconvenienced, at an inappropriate time.


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## FalkeEins (Mar 26, 2009)

..absolutely .. at 30,000 ft in an unpressurised WWII fighter, farts (or at least the build up of gas in the intestine) can be excruciatingly painful - enough to incapacitate the pilot ...German pilots of course loved bean or pea soup ..but couldn't risk eating either any time prior to a sortie..


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## Njaco (Mar 26, 2009)

Caity is just a catankerous old fart! 

Besides in this day of Global Warming, I think this topic is appropriate.

(_cranks up Monty Python...._)
"Are you embarrassed easily?...."


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## RabidAlien (Mar 26, 2009)

Njaco said:


> (_cranks up Monty Python...._)
> "Are you embarrassed easily?...."



Classics!!!!


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## Gnomey (Mar 26, 2009)

Yep absolute classics.

That guy has no sense of humour and Njaco has hit the nail on the head a cantankerous old fart


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