Nitrogen and oxygen are the two main gases in the air that people breathe. Air is in the lowest 6.2 miles of the atmosphere and is made of 78 percent nitrogen, 21 percent oxygen and 1 percent trace gases and aerosols.
Nitrogen and oxygen are colorless, tasteless and odorless, yet they are important to the survival of plants, animals and humans. Oxygen is necessary for respiration, and without oxygen, life on Earth would not exist. Oxygen is also necessary for fires to burn. Nitrogen is found abundantly in the atmosphere, and it is necessary for the nutrition of plants and animals.