Breath Control

Using Breath Control, a user can literally numb the body's instinct to shut itself down after long periods without oxygen, allowing the user to be able to go without breathing for longer periods than they ordinarily could by using the Force to reserve the amounts of air in the lungs.

It is believed that some users of the technique can hold their breath for hours or even days with this power. This ability used independently, however, will not prevent anything entering or leaving the respiratory system of the user. In some cases, the user requires some kind of Force barrier in or around the nose/throat region to keep poisonous gases or water out. The necessity of such a barrier depends on the air/water pressure in the direct vicinity, and the user's ability to naturally seal their airways.

This is a very effective ability in situations where the air is very thin, underwater, or in any environment with toxic fumes.

=Sources= Wookieepedia