As humans, we are highly dependent upon oxygen in order to carry out our normal functions and maintain consciousness. As one increases their position in altitude, the amount of air pressure decreases as well which results in less amounts of oxygen that one can absorb while breathing. At the heights at which aircraft typically operate at, humans would not be able to maintain consciousness long due to a lack of oxygen. Despite this, most passengers are never faced with much discomfort during a typical flight. This is due to the use of oxygen systems within pressurized and non-pressurized aircraft, those of which maintain a comfortable environment by supplying breathable air.