Not all people have flammable gases, but only 30% of humanity. They become flammable due to methane impurities. The formation of methane in the composition of gases is associated with the presence of the bacteria metnanobrevibacter smithii in the intestinal flora. It is believed that this property of intestinal gases is a hereditary predisposition. Gastrointestinal gases burn with a bluish-yellow flame. In the process of fermentation of food gruel in the right (ascending) section of the large intestine, hydrogen and carbon dioxide are formed, and in the process of decay in the left (descending) section, methane and hydrogen sulfide "ripen". All this mixes with nitrogen and oxygen, which enter the stomach and then into the intestines during the process of eating and drinking. Thus, when digesting an average dinner, about 15 liters of gases are formed. However, only a few percent come out of them, while the bulk penetrates through the intestinal walls into the blood, and then is exhaled by the lungs. Under normal conditions, it comes out from 0.1 to 2.1 liters per day. When swollen, more than 5 liters can escape. 99 percent of gases are odorless. During normal digestion, gases come out imperceptibly, but at the slightest imbalance, "gases that people can recognize with the senses" appear. Eating foods rich in ballast substances and vegetarian diets lead to a significant increase in enzymatic processes and increased production of hydrogen, and as a result, "gases noticeable to people".
Oh yes, when gases ignite, not only clothes, but also the large intestine can be damaged. Good luck with your experiments :)
True. The composition of the gas mixture in humans is as follows: nitrogen, carbon dioxide, oxygen, hydrogen, methane, as well as a small amount of hydrogen sulfide, ammonia, etc. Hydrogen and methane are a combustible mixture, which is why when you ignite a bunch, it burns.