Well, I am obsessed with this. I think I find this really amusing for some reason I can't narrow down on.
The composition of fart varies dramatically among individuals. Five simple odourless gases are their major components. Flatulence produces a mixture of gases such as nitrogen, carbon dioxide, methane, oxygen, hydrogen and hydrogen sulphide. The gas methane combusts, forming water and carbon dioxide.
- CH4(g) + 2O2(g) → CO2(g) + 2H2O(l)
- 2H2S(g) + 3O2(g) → 2SO2(g) + 2H2O(l)
The odour associated with flatus is due to hydrogen sulfide, skatole, indole, volatile amines and short-chain fatty acids. These substances are detectable by olfactory neurons in concentrations as low as 10 parts per billion, hydrogen sulfide being the most odorous. So blame them for all the disgusting smell!