From a US patent for a flatulence deodorising pad that sits in your underwear (in, the patent helpfully informs us, “the anal area”).
The background notes make for compelling reading (the charcoal cloth of which the pad is made was originally developed to defend soldiers against chemical warfare), but I particularly like the idea that somewhere there’s an illustrator whose specialty is the infographics of the fart.
(Google Patents, via Amy and Aaron Edgar)