Now that we know this, think of how amazing this is. Someone is fully clothed, has a couple layers of finely woven fabric and quite a bit of air between your nose and the orifice that emits the gas. Awesome how fast the 'gas' can permeate a car, an elevator, or a classroom isn't it. It isn't as if your friend or partner directed this emission directly at your face (or maybe I shouldn't have made such assumptions) So when you smell it, you can pretty much be assured the entire area is equally distributed with these particles floating and landing on all around you. The time between the emission and the sensation of smell when you think about it is incredibly short.
Now think of what solid particles are added to the fart by your friend so you may have the benefit of smelling it, and knowing those same particles are landing on your food, in your drink, in your hair, on your toothbrush...etc.
(note: the boyscouts especially love this when we talk about safety with coleman stoves. There is a lot more groaning and yelling that evening in their tents)