Let 'Em Rip!

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 boring, 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. Encyclopaedia Britannica offers the intriguing statement that some people's farts contain no methane. The reason for this is apparently unknown. Some researchers suspect a genetic influence, whereas others think the anomaly 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 skatole in the mixture. These compounds contain sulfur. The more sulfur-rich your diet, the more sulfides and skatole 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.
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.
How long does it take fart gas to travel to someone else's nose?
Fart travel time depends on atmospheric conditions such as humidity and wind speed, as well as 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.
Is it true that some people never fart? No, not if they're alive. People even fart shortly after death.
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.
At what time of day is a gentleman most likely to fart?
A gentleman is mostly likely to fart first thing in the morning, while in the bathroom. This is known as "morning thunder," and if the gentleman gets good resonance, it can be heard throughout the household.
Why are beans so notorious for making people fart?
Beans contain sugars that we humans cannot digest. When these sugars reach our intestines, the bacteria go wild, have a big feast, and make lots of gas! Other notorious fart-producing foods include corn, bell peppers, cabbage, milk, and raisins. A friend of mine had a dog who was exceptionally fond of apples and turnips. The dog would eat these things and then get prodigious gas. A dog's digestive system is not equipped to handle such vegetable matter, so the dog's bacteria worked overtime to produce remarkable flatulence.
What things other than diet can make a person fart more than usual?
People who swallow a lot of air fart more than people who don't. This can be cured somewhat by chewing with your mouth closed. Nervous people with fast moving bowels will fart more because less air is absorbed out of the intestines. Some disease conditions can cause excess flatulence. And going up in an airplane or other low-pressure environment can cause the gas inside you to expand and emerge as flatulence.
Is a fart really just a burp that comes out the wrong end?
No, a burp emerges from the stomach and has a different chemical composition from a fart. Farts have less atmospheric gas content and more bacterial gas content than burps.
Is it harmful to hold in farts?
There are differences in opinion on this one. Certainly, people have believed for centuries that retaining flatulence is bad for the health. Emperor Claudius even passed a law legalizing farting at banquets out of concern for peoples' health. There was a widespread belief that a person could be poisoned or catch a disease by retaining farts. Doctors I have spoken to recently have told me that there is no particular harm in holding in farts. Farts will not poison you; they are a natural component of your intestinal contents. The worst thing that can happen is that you may get a stomach ache from the gas pressure. But one doctor suggested that pathological distention of the bowel could result if a person holds in farts too much.
How long would it be possible to not fart?
As I understand it, a captive fart can escape as soon as the person relaxes. This means that a lot of people who assiduously refrain from farting during the day do so at great length as soon as they fall asleep. Having been on a great many overnight field trips, long bus trips, and trans-Pacific flights, I can personally vouch for the fact that lots of people do fart voluminously as they doze off. So the answer to the question would be, you can refrain from farting as long as you can stay awake!
Where do farts go when you hold them in?
How often have you held in a fart, intending to release it at the first appropriate opportunity, only to find that the fart has disappeared when you are ready for it? I asked several doctors where the fart goes. Does it leak out slowly without the person knowing it? Is it absorbed into the bloodstream? What happens to it? The doctors agree that the fart is neither released nor absorbed. It simply migrates back upward into the intestine and comes out later. It is reassuring to know that such farts aren't really lost, just delayed.
Is it really possible to ignite farts?
The answer to that is yes! However, you should be aware that people get injured igniting flatulence. Not only can the flame back up into your colon, but your clothing or other surroundings may catch on fire. A survey done by Fartcloud (the site, alas! is not more) indicates that about a quarter of the people who ignited their farts got burned doing it. Ignition of flatulence is a hazardous practice. There have also been cases in which intestinal gases with a higher than normal oxygen content have exploded during surgery when electric cautery was used by the surgeon.
Why is possible to burn farts?
Farts burn because they contain methane (usually) and hydrogen, both of which are flammable gases. (Hydrogen was the same gas that was used in the ill fated Hindenburg dirigible.) Farts tend to burn with a blue or yellow flame.
Is it possible to light a match with a fart?
No, even strike-anywhere matches have their limits, unless the fart has the consistency of sandpaper! Any fart that rough I would hesitate to call a fart. Also, farts have the same temperature as the body from which they emerge, and aren't hot enough to initiate combustion.
Why do dog and cat farts smell so bad?
A carnivore's protein-rich diet produces relatively small amounts of intensely stinky gas because proteins contain lots of sulfur. A dog's or cat's farts are rarely audible, but the odor is overwhelming. I have asked biologists why dogs and cats generally fart silently, and their theories include: (1) the amount of gas produced is small, but potent, (2) the horizontal orientation of their gastrointestinal system puts less pressure on the anal opening, so the gas is expelled more slowly, (3) their anal sphincters don't close as tightly as humans' because it takes less force to hold in the contents of the colon -- again because of the horizontal orientation of the gastrointestinal system -- and a loose anus makes less sound, and, my favorite (4) dogs and cats don't feel embarrassed about farting, so their sphincters are more relaxed, leading to less noisy flatulence. Mike F. points out that many dog foods are soy-based, so on top of all the above factors, add beans and stand back! Large herbivorous animals such as cows, horses and elephants, on the other hand, produce vast quantities of relatively non-stinky fart gas. The farts of these animals are noisy and can go on for astoundingly long periods of time. Cows in particular are productive, in part because they swallow huge amounts of air. They need oxygen in their guts for the various protozoa employed there as digestive aids.
What kind of animal has the highest worldwide output of flatulence?
Believe it or not, the animal that wins this honor is the humble termite. Because of their diet and digestive processes (with more than the usual microbial assistance), they produce as much methane as human industry. Termite farts are believed to be a major contributor towards global warming.
Is it possible to leave a brown spot on your pants because of a fart, and if so, what causes it?
Judging from what I see when I do the laundry, I'd say that the answer to the first question is definitely yes. As for the causes, we must remember that what we call "fart" and what we call "poop" are just end-members of a continuum. That is, we can have a pure fart, or a pure poop, or anything in-between, depending upon the admixture of the two. If a sample consists mostly of poop with only a small fart component, you get such things as jet-propelled bowel movements and spongy, floating fecal masses (you know, the ones that refuse to be flushed down the toilet -- they keep popping back up). If the sample consists mostly of fart with only a small poop component, you get what is known as "skid marks" or "fart art." These can also result from inadequate wiping, but the shape of the stain is different in the two cases. Inadequate wiping leads to elongate marks parallel to one's crack, usually with well-defined edges, whereas fart art is generally more circular and has an air-brushed look. Fart art is most likely to occur if (1) a person is suffering from diarrhea, (2) the person is trying too hard to fart, and (3) the person mistakenly perceives the pressure against his sphincter to be gas pressure rather than liquid pressure. Again, that last situation is most likely to occur if the person is afflicted with diarrhea.
How can we tell when it's only gas needing to come out, rather than something more serious?
Our ability to distinguish between the need to fart and the need to poop is something that we learn gradually in the process of toilet training and early childhood. With the tactile nerve endings in the rectal area, we can actually feel different sensations depending upon what is waiting by the exit. Of course, sometimes we are fooled, especially if the substance at hand is extremely fluid in nature, and that is when we have the unfortunate accident of venting a squirt of diarrhea rather than an innocent fart.
What causes the burning sensation that sometimes accompanies a fart?
This is generally caused by a recent meal of hot peppers or related spices. The oils associated with these foods remain intact and active all the way through one's gastrointestinal system.
If you fart in the bathtub, is the water polluted and should you refill the tub? As long as what comes out is only fart and no poop, your bath water should not be significantly polluted. Most of the gas just bubbles up and contaminates the air rather than the water.
What color is a fart?
Farts are, alas, colorless. All of the gases that make up farts have no inherent color. But just think of how interesting it would be if farts were bright orange like nitrogen dioxide gas! It would certainly take the mystery out of who farted. Never-the-less, a high-personality gas like fart gas suggests color to people. Some people envision farts as brown, others as green or yellow. I have always thought of farts as brown, presumably because poop is brown. When someone farts in our car, that person might say, "You better not breathe through your mouth for awhile, or your teeth will turn brown." I knew a toddler who used to draw pictures of farts as yellow rectangles full of holes, like a slice of Swiss cheese. She thought of farts as yellow, and said that she knew they were rectangular because she could feel the sharp corners scraping against her on the way out!
Why is it that when you scratch your ass through two layers of clothing (your underwear and your jeans) your fingers still stink?
As pointed out by Barb F., who contributed the term listed below, a fart can be regarded as "aerosolized poop," which means that microscopic fragments and droplets of poop are actually distributed throughout the gaseous matrix of the fart. When delivered from the anus with some force, the components of the fart can penetrate one's clothing and these tiny particles can be trapped in the fibers of the cloth. The particles are transferred to your fingers and then your nose when you scratch and sniff.
Where does the word "fart" come from?
According to Eric Partridge in his excellent book of word origins (Origins: A Short Etymological Dictionary of Modern English), our word fart comes from the Old English word feortan, presumably of echoic origin, meaning that the word was chosen to sound like the object named.
When it is cold outside and you fart, can you see it like you can see your breath?
Now, that's an interesting idea! My guess would be yes, since farts are nice and moist like our breath, but this is one question that I'm not in a position to answer. I live in the tropics, and it never gets cold here. So all of you who live in cold places, try it out and let me know. I'd guess that there are really two questions here: can you see the fart with no pants on, and can you see the fart even with pants on...
Types of farters
Bugle bum: Australian term for someone who farts a lot. (contributed by Michi) Fart blossom: a producer of particularly redolent farts.
Fartmeister: an expert and accomplished farter.
Methane makers: people who fart a lot.
Organ arse: Australian term for someone who farts a lot.
Snorkeldorfer: a person who farts underwater and then sticks his nose in the bubble.