READER QUERY: “I have a friend who claims that he has set light to his farts. Can this be done, and is it dangerous?”
The gases released during flatulence are indeed flammable.
Gut bacteria produce a wealth of flammable gases, primarily hydrogen and methane, and foul-smelling farts are potentially the most flammable, as they include the hydrogen sulphide which smells like rotten eggs.
The mix of gases varies with the food eaten and the quantity and type of bacteria in the gut. So the flammability varies between people.
Hydrogen, the most flammable gut gas, is very easily lit – even in concentrations down to 4%. Gut bacteria produce hydrogen as they break down fibre, such as beans.
Depending on the quantity of fibre consumed, hydrogen content of flatulence can vary between 8% and 63%. Hydrogen, methane and carbon dioxide together make up some 75% of a typical fart. As the gases mix with the oxygen of the air, they form a flammable cocktail.
The flame from an ignited fart is usually very brief. Hydrogen burns quickly, and farts have an average volume of only 100ml. People with special abilities beyond this have become famous. Joseph Pujol was one of the most popular and highly paid stage performers in Europe prior to World War I, known as Le Pétomane (the gas maniac). There is evidence of “fartistes” dating back to the 4th century AD, and during Japan’s Kamakura era (ending 1333) a man named Fukutomi no Oribe would perform fart dances for the aristocracy.
A warning, however: although it may sound like fun, it is not recommended to ignite a fart. The flame can spread in the direction of the rectum, causing severe burns to the body or hands.
GAS SEEPS OUT OF THE RECTUM: Gut bacteria produce flammable gases such as hydrogen, hydrogen sulphide and methane. A fart can include some 63% of hydrogen, which is the most flammable gas the guts can produce.
HEAT BOOSTS CHEMISTRY: When the hydrogen is mixed with oxygen in the air and subjected to the heat of a flame, a combustion reaction results, in which hydrogen and oxygen react with each other, developing water, light, and heat.
BLUISH FLAME DEVELOPS: The more hydrogen in a fart, the more bluish it is. The colour is a sign of complete combustion. Reddish yellow flames from candles or fires are the result of solid particles such as soot.
