ABSTRACT
Air is a critical element to many living things. People, for example, may survive for two weeks without food and for two days without water. But without air, a person may only survive for two minutes. In daily life, an average person consumes approximately 1 kg of food, 2 kg of water, and 20 kg of air. Further, in developed countries, an average working person spends over 90% of his or her lifetime indoors.
