Air n the earth's atmosphere consists of about 79 percent nitrogen, 20 percent oxygen and 1 percent other gases such as argon and carbon dioxide. Humans have discovered many uses of air from simple to complex. Science, economics and safety not only use air but depend on it.
The most obvious way humans use air is breathing it. Lungs take in oxygen from air and transfer it to the bloodstream for distribution to the rest of the body. Carbon dioxide is sent from the body back to the lungs where it is expelled from the body. Air has been harnessed by ventilators and hyperbaric pressure machines used to maintain life in disease states.
Many sports depend on the use of air, such as football, soccer, basketball, paint-ball sports, and air boating. Without various materials inflated with air to various degrees, these activities would be nonexistent.
Humans have found a way to compress air and use it in tanks that deliver it to equipment such as tires, mechanics' tools, aerosols, hot-air balloons, mattresses, compressors that run electricity and the refrigerant Freon.
People enjoy the convenience of air at home through ventilation systems, baking dishes, fans, the clothes dryer and other appliances.
