Ask Dr. Svinktor:
Everything You Wanted to Know About Farts
We found this information posted anonymously on
a web board. It answers some of the most commonly asked questions
about farts. Dr. Svinktor wanted to share it with you.
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
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
Do even movie stars fart?
Yes, of course. So do grandmothers, priests, kings,
presidents, opera singers, beauty queens, and nuns. Even Yoda farts.
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
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
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
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,
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
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.
Are there any books about farting?
There are several! My favorite is the new book,
Who Cut the Cheese: A Cultural History of the Fart by Jim Dawson.
This book provides an entertaining and thought-provoking history
of the fart in literature, language and society. It is very informative
and very funny! Ben Franklin's classic Fart Proudly is still in
print. There is a collection of suggestive photographs called Who
Farted Now? by St. Martin's Press. Most of the photos come from
old movies and political shots. For children, we have the famous
The Gas We Pass : The Story of Farts by Shinta Cho, and Amanda Mayer
Stinchecum (Translator), and the Canadian picture book, Good Families
Don't , by Alan Daniel and Robert N. Munsch, about a highly visible
fart infesting a proper middle class family.
Is it possible for a talented person to earn a
living through flatulence?
Few people earn their living directly via flatulence.
But a friend of mine says that he saw a carnival act in which the
performer whistled tunes with his farts, blew out candles on the
opposite side of the stage, and sent flames all the way across the
stage. A famous performer who earned his living this way was Le
Petomane, who performed in France at the beginning of the 20th Century.
However, my friend isn't old enough to have seen Le Petomane, so
maybe he had a chance to see Mr. Methane. Mr. Methane lays claim
to the distinction of being the world's only performing flatulist.
However, people may also earn a living through the
prevention of flatulence (as do the manufacturers and sellers of
Beano and other products), through the practice of medicine specializing
in the treatment of flatulence and other gastrointestinal problems,
by writing books about flatulence (see the question before this
one), and through the production and sales of various fart gags
such as whoopee cushions and farts in a can.
Fartypants sells a fart filter and a number of other
Maybe, if you're lucky, you'll be able to find a copy of Le Petomane's
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
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.
Do fish fart?
According to our ichthyologist at the University
of Guam, fish flatulence per se has not been studied, although people
have investigated fish digestion. They find that although most fish
have alkaline intestinal environments like our own, coral-eating
fish have acidic intestinal contents. The acid serves to dissolve
coral skeletal material. Coral has the same composition as Tums
(calcium carbonate). One product of the reaction between acid and
calcium carbonate is carbon dioxide gas. Therefore, it is logical
to assume that coral-eating fish fart a lot. The other fish probably
fart also, for the same reasons that we do. However, Mike Pulte,
a great fish enthusiast, said that he has never seen a fish do it.
I asked our ichthyologist if it were possible that
fish gas would go into the swim bladder instead of out the anal
opening. He said that modern fish have an air bladder that is independent
of the gastrointestinal tract. The gas comes from enzymatic activity
and not from the intestine. Older models of fish have their swim
bladder connected to the gastrointestinal tract, but it is attached
high up, closer to the mouth than to the other end, and these fish
come to the surface and gulp air to fill the bladder. Therefore,
we can assume that intestinal gas leaves the fish through the anal
We also pondered the possibility of fish making
noise via flatulence, but apparently most fish noises are made through
belching rather than farting.
Lisa P., an aquarium enthusiast, reports that she has seen her fish
fart: "I have four aquariums and many fish, and I have personally
witnessed fish farting! My goldfish used to do it all the time!
You'd see a little bubble come out of his anus and stay there, trapped
in the mucus of a long string of poop. (Ugh!) And my opaline gourami
does it too. Neither of these are coral-eating fish. I have only
owned two coral-eating fish so far, but I have never seen either
of them fart. It seems most likely to me that much of this gas comes
from air swallowed during eating. Also, goldfish have a very simple
digestive system and their food is absorbed inefficiently, so possibly
the bacteria have more to feed on?"
Do turtles fart?
Yes, turtles do fart, and their farts smell incredibly
bad, as do the farts of snakes. In fact, it is my opinion, based
on personal experience with reptiles and not on any formal research,
that many reptiles use farts as a weapon.
Reptile farts smell so bad that sometimes you can tell that one
is nearby in the woods, even on a windy day, before you can see
the animal. One day I was hiking through the woods in Arkansas with
a friend and I told my friend, "I smell a snake fart."
A second later, the snake crawled across the path. Astounding but
What kind of animal has the highest worldwide output
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 there any kind of animal that doesn't fart?
If we define a fart to be an anal escape of intestinal
gas, then it follows that animals that lack intestines or an anus
cannot fart. Most animals possess intestines and an anus, but there
are some that don't. These include:
Sponges: These organisms lack true tissues and organs. They have
just a few types of cells organized into a bag with holes in it.
Water flows into some holes and out other holes. Sponges are so
different from other animals that some biologists think we shouldn't
even call them animals.
Cnidaria: This phylum includes the jellyfish, corals,
sea anemones and hydra. Their tissues are organized into a bag with
a mouth surrounded by stinging tentacles. Food enters the mouth
and is digested inside the bag, after which the leftovers are expelled
via the same opening. In effect, the same hole serves as both a
mouth and an anus. Any gas expelled by a cnidarian would be more
appropriately termed a belch rather than a fart, since the animal
lacks intestines and separate anus.
Pogonophoran worms: These remarkable animals, who
dwell on the sea floor near active volcanic regions associated with
mid-ocean ridges, possess no mouth, no stomach, no intestines, and
no anus. Apparently they retain their svelte, worm-shaped figures
by giving up on eating completely! They survive by means of a mutualistic
relationship with chemosynthetic bacteria that live in their flesh.
Anyway, these animals cannot possibly fart.
A second category of animals that probably don't
fart are animals that live very deep underwater. At high pressures,
gas remains in solution rather than forming bubbles. So there is
a good chance that all those clams, echinoderms, fish and other
animals living near the sealer don't fart because their farts stay
in solution and never emerge as bubbles, even though the animals
possess perfectly good intestines and anuses.
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
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
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
Why do chicks always deny farting?
I suppose I should start by saying that only some
chicks deny farting. The rest of us acknowledge our gaseous accomplishments
with pride. However, a great many sisters do deny farting. The reason
is that they have been misled into thinking that farts are not ladylike.
It is a great mistake to say that farting is not ladylike. The reason
is that all people fart, including ladies. Anything that ladies
do is by definition ladylike, and that includes the emission of
Is is possible that, by inhaling other people's
farts all day long, my own farts will smell more?
No, inhaled farts would go into the lungs rather
than into the digestive system, and would simply be exhaled again,
although it might be possible that some of the fart components might
be absorbed into the blood. If you wanted to benefit from other
people's farts in the way you describe, you would have to swallow
Is it possible to get stoned after inhaling two
or three farts in a row?
I am not aware of any intoxicating agents in flatulence.
However, most farts contain very little oxygen, and you may experience
dizziness if you are inhaling overly concentrated fart essence,
simply from lack of oxygen. On the other hand, if you are inhaling
farts in the open air and are breathing rapidly in order to inhale
as much fart as possible, you may be hyperventilating, which also
Then there is the intrinsic hilarity factor: farts
are so funny in both sound and odor that you might feel high just
from the basic entertainment value of farts.
Is it possible for a fart to kill you?
A great many of you have asked if farts can be fatal,
or if you can die from smelling a particularly bad fart. My initial
response to this question was "no," but I thought I'd
better ask a doctor. So now it is official, the medical opinion
I received is no, a fart can't kill you.
However, if you really work hard at it, you can
manage to kill yourself with just about anything. I recently read
of a man who hooked up his nose to his anus with a system involving
a gas mask, rubber tubing and a hollow wooden post. He died of suffocation.
This story comes from the Darwin Awards, and I personally cannot
attest to the overall veracity of their stories. The story of the
bed-bound obese man who died from inhaling his own flatulence (and
whose farts almost killed the paramedics) is an urban legend that
has been in circulation for some time.
Can excessive farting cause impotence?
That depends on the tolerance level of the person
with whom one is trying to be potent! Fortunately for humans, farting
doesn't cause tissue damage. Other animals aren't so lucky. Soldier
termites can actually turn themselves into bombs by detonating themselves
via the explosive release of gas and feces, a process called "autothysis."
Is it possible to inhale (suck in air) via one's
Yes, but it's a rare talent. The great early 20th
Century French flatulist, Le Petomane, was able to do this, and
in fact was able to suck up an entire bowlful of water (just the
water, not the bowl) into his colon and expel it again with considerable
force. By sucking in large quantities of air, he was able to perform
lengthy shows on stage, and could imitate musical instruments, farm
animals, and bird songs, whistle melodies, and play the ocarina.
His productions were said to be virtually odorless, which is to
be expected from air obtained directly from the outside.
Here is a message I received recently (November, 1999) regarding
the skill of inhaling via the anus:
"I would just like you to know that i am part
of a trio, who can suck in air in our anal openings. We are somewhat
air-bandits. We can let the longest farts you have ever heard. Our
record holder, chad, stands at 24 sec. the record for most farts
in a row is derek, at 492. and I, Robert, have earned such nicknames
as: Mad Crapper, gurglemeister, and old wetful. We have followed
Le Petomane example, and have mastered the art of farting."
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
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.
Is it true that a woman can fart out of her, shall
we say, frontal opening, and if so, where does the gas come from?
Yes, it is true! The gas that emerges is simply
trapped air, for there is no gas production in the genitalia of
a woman. The air can enter because the system is open to the outside.
This highly specialized kind of fart is sometimes called a queef.
Can a man fart out of his genital opening?
I have asked various men this question and they
all deny it emphatically.
Is it possible to capture a fart in a jar and save
it for later use?
It should be theoretically possible to do this,
but there would be lots of logistical problems. I would suggest
using a plastic bag instead of a jar. You might try the following
as a science fair experiment:
Fart into several plastic bags and seal them carefully.
Then fill several other plastic bags with ordinary air. Wait 24
hours. Then get volunteers to smell the contents of the bags to
see if they can correctly identify which ones contain the farts.
This should tell you if it is possible to store a fart in any useful
Malachi and Megaera have come up with a way to capture
a fart in a jar. They say to do it in the bathtub while bathing.
Fill the jar with bath water and then hold it with the open end
downward. Lean back in the bathtub so that your fart bubbles will
emerge in front of you rather than behind you where you can't see
them. Catch the bubbles in the jar, and put the lid on the jar while
it's still underwater. This way, you capture a fairly pure fart
uncontaminated by atmospheric air. To enjoy your captured fart to
the fullest extent, make sure that your jar does not already smell
like whatever was it it before, like pickles or peanut butter.
Is it weird to enjoy farting?
It is not unusual to enjoy farting. I believe that
enjoyment of farting is a healthy attitude, since everyone has to
fart. If a person is farting to the extent that it creates problems
and unhappiness, then a visit to a doctor is in order.
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!
Do other people smell a fart better than the farter?
The fart should smell just as much for the person
who created it as it does for other people. However, the farter
is somewhat protected by having the fart propelled away from his
body in a direction opposite to his nose. Farting upwind nullifies
Why is it that when you scratch your ass through
two layers of clothing (your underwear and your jeans) your fingers
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...