At the Minneapolis Veterans Affairs Medical Center, a group of people set out to try and find a material that would help minimize problems with odoriferous rectal gas – aka fart smell.
The tests were done by instilling a tube of 100 ml of nitrogen containing 40 ppm of sulfide gases and 0.5% H(2) at the anus of six healthy volunteers. They volunteers all wore gas impermeable Mylar pantaloons over their garments. They then had them put pads inside the underwear with a variety of materials.
If no pad was in place, the garment alone remove about 5.3% of the sulfide gases. Most of the materials were not very effective, absorbing about 20% of the gases. The best of the bunch were briefs constructed from an activated carbon fiber fabric, which removed 55-77% of the sulfide gases.
Conclusion? Get some carbon fiber briefs if you don’t want people to smell your farts.