Just about everyone knows that oxygen is critical to human life and that going without it for more than just a couple of minutes is incompatible with maintaining that life. And if you've had a look around the medical, industrial and aerospace worlds, you've probably seen oxygen storage systems well represented in each of these areas.

What, fundamentally, is oxygen, and just how handy is this element in everyday life, in addition to being the gas that literally keeps you laughing (and talking and breathing)? Read on, and you'll be surprised at the utility of this ubiquitous substance. Oxygen has many uses other than keeping you animated!

Oxygen is element number 8 on the periodic table of elements. Molecular oxygen, or oxygen gas, has the formula O_₂_ and is therefore diatomic (has two atoms). It can exist as a liquid at extremely low temperatures.

Oxygen makes up about 21 percent of the gas in the atmosphere. Fortuitously, this is halfway between the 17 percent needed for many creatures to sustain life and the 25 percent level at which oxygen's flammable nature becomes a concern.

Oxygen appears chiefly in biomedical, manufacturing and aerospace contexts in the modern world, and the importance of oxygen extends well beyond human and animal respiratory systems.

The role of oxygen in the human body cannot be exaggerated. The body systems involved with oxygen include literally all of them, for all living human cells require a constant supply of oxygen or else they die within minutes. Widespread cell death in the same area leads to tissue death, or necrosis.

Oxygen, discovered in 1774 by Joseph Priestly, is necessary for combustion, and oxygen is therefore used in metallurgy, which requires extremely high temperatures to bring about the required chemical reactions.

The main specific uses of oxygen are best summarized by separating them into the three convenient categories referred to above.

Physiological Uses of Oxygen:

• In cells, oxygen is needed for aerobic respiration, which allows for the extraction of energy from ingested foods. Thus supplemental oxygen at home and in hospitals is vital for those with breathing disorders such as emphysema.
  
  
• Compressed oxygen tanks are used by mountaineers at high elevations to counteract the decreased O₂ pressure at these altitudes.
  
  
• Supplemental oxygen is needed for surgical patients intentionally rendered paralyzed for medical procedures, in which "heart-lung machines" keep their vital functions going.
  
  
• Oxygen can be used as a sterilizing agent to kill certain anaerobic bacteria that are killed by sufficient exposure to the gas.

Industrial Uses of Oxygen:

• Oxygen is needed for the reaction that converts carbon to carbon dioxide gas in steel working, which takes place under high temperatures in a blast furnace. The carbon dioxide produced allows for the reduction of iron oxides into more pure iron compounds.
  
  
• Oxygen is used in other applications involving metal and requiring high temperatures, such as welding torches.

Aerospace Uses of Oxygen:

• In liquid form, oxygen is used widely as an oxidizing agent for use in missiles and rockets, where it reacts with liquid hydrogen to produce the terrific thrust needed for take-off. Astronaut spacesuits include a nearly pure form of oxygen. 
  
  
• Oxygen is used to degrade hydrocarbon compounds, which are broken apart by heating them. This is used to create combustion that usually liberates water and carbon dioxide, but can also produce the hydrocarbons acetylene, propylene and ethylene.
  
  
• Oxygen is used in sewage-treatment and water-purification plants. It is forced through water to increase the production of bacteria that metabolize waste products in the water.
  
  
• Oxygen gas (O₂) is needed to produce energy in things not linked to an electrical supply of their own, such as generators and vehicles (e.g., ships, airplanes and cars).