Where do all the farts go?

Answer 1

The gases expelled from the body during flatulence--called the flatus by doctors--are the same as the primary gases normally found in the air. The main gas in flatus is nitrogen, which is also the largest component of air. Some flatus contains up to 10% methane, while other flatulence contains none. When a fart smells offensive, this is because broken-down proteins in the digestive tract are being carried by the flatus. The type and concentration of those smelly molecules will vary based on diet and the health of gastrointestinal bacteria. Ultimately, the cumulative effects of farting are not significant. Flatus disperses into the air harmlessly. Fun fact: People who drink Carbonated Beverages tend to have more carbon dioxide present in their flatus. Don't blame the fart: Livestock flatulence is often identified as a significant source of greenhouse gases, due to the presence of methane in flatus. Cows, however, release most of their methane by exhaling or burping. Only 1-2% of global methane emissions originate from cow farts.

Answer 2

I guess it all depends on the orientation of the fart's... errrr... source...

Apart from that, once released, the motion of the fart depends on its density.

Assuming that the fart was mostly methane (a poor assumption, but it'll have to do), you can see that the density of the fart was about 0.7 kilograms per cubic metre (kgm-3).

At sea level, Earth's atmosphere is about 1.2 kgm-3, that is, it's denser than the fart.

This means that the fart will float, thus it will go up(and stink out the whole building).