On airliners its because you're flying at very high altitudes which means there is very little oxygen and if one of the windows are broken that air will come so if you don't have the oxygen masks you'll die from lack of oxygen
in case of an emergency like there is a gas leak, or there are toxic fumes released into the air, or if the plane is about to crash and people start to panic
John Q. Tilson has written: 'The Tilson family' 'Arms, ammunition, airplanes, and gas masks' -- subject(s): Airplanes, Ammunition, Firearms, Gas masks
When flying at hight altitudes (+12,000FT) planes pressurize the cabin so passengers can stay conscious without wearing oxygen masks.
oxygen
by gas masks and oxygen packs.
It doesn't--this is just an urban legend. Pressurized airplanes can usually maintain cabin pressure with one or more windows completely missing, but even if they lost all cabin pressure, the pilots would use oxygen masks and the emergency masks would drop in front of the passengers. Then the airplane would descend to under 10,000 feet where you wouldn't need oxygen.
Oxygen is available in emergency overhead masks in passenger aircraft
For oxygen masks for firefighters, scuba divers etc
The more oxygen the get the faster it diffusses to the cells.
Modern airliners and aircraft that fly above 15,000 feet are required to be pressurized because the oxygen levels at such high altitudes are not sufficient for the human body's needs. If much time is spent above these altitudes without pressurization or supplemental oxygen, hypoxia can result. The symptoms of hypoxia, or a lack of oxygen in the bloodstream, include nausea, discoloration, disorientation, and severe headaches. Not all airplanes are pressurized, however. Pressurization is limited to airliners, private jets, expensive personal aircaft, and high-altitude military aircraft. An alternative to pressurization is supplemental oxygen masks connected to oxygen tanks somewhere in the aircraft. Pilots are required to wear oxygen masks when flying above 12,500 feet for any longer than 30 minutes. At 14,000 feet, pilots are required to use supplemental oxygen at all times. At 15,000 feet, everyone on board must have supplemental oxygen.
Oxygen masks are needed at higher altitude because the air is less dense, therefore less air molecules are getting into your lungs when you breath.
Tires for trucks and planes soles for shoes gas masks and oxygen masks
There are many different places in which someone could purchase oxygen masks made by Bliss. The best websites are Amazon and Ulta because they offer different types of masks.