Air has many uses. Some of them are as follows:
1. Air contains oxygen, which is essential for life. All living things respire by breathing in air. The air we breathe in is inhaled air. The air we breathe out is exhaled air.
2. Air supports burning or combustion. The oxygen present in air is essential for burning. We burn fuels to cook food, generate heat and electricity, run industries and drive vehicles. The presence of nitrogen reduces the activity of oxygen. If air contained mostly oxygen, even small fires would turn into huge explosions!
3. The nitrogen present in air is essential for the growth of plants. Plants take in nitrogen directly from the air or from the soil.
4. A layer of ozone gas present high up in the atmosphere protects us from the harmful ultraviolet rays of the sun. Also during daytime, the atmosphere prevents excessive heat from the sun from reaching us. At night, the atmosphere traps the surface heat and prevents it from escaping.
5. Moving air, called wind, has great force. It enables the movement of sailboats and gliders. It runs windmills, which are used to generate electricity. Wind also helps in the dispersal of seeds.
6. Compressed air is used in a number of ways. It is used to fill tyres. Many machines make use of compressed air. For example, machines used in mining and digging and the drill used by dentists work on compressed air.
7. Carbon dioxide is taken from air by plants for photosynthesis, the process of making their food. The air we breathe out contains carbon dioxide. Exhaled air can be tested for the presence of carbon dioxide.