Oxygen is essential for combustion (burning), corrosion, and respiration. If the amount of oxygen is increased in the air then the processes such as combustion, corrosion, and metabolism will become very fast and lead to harmful results. It can be explained as below
If the amount of oxygen is increased in the air then the rate of metabolism in the bodies of human beings and other animals will become very fast due to which their health will be damaged. Since the oxygen is a supporter of combustion, so when the amount of oxygen is increased in the air then the process of combustion will become very rapid. All the fuels will burn very rapidly and dangerously. If a fire breaks out then it will be very difficult to extinguish it. The increased amount of oxygen in the air will cause very rapid corrosion of metals. Just like, iron will get rusted very quickly. In the presence of more oxygen, the fruits and vegetables will get spoiled more quickly and the colors of clothes will fade or disappear more rapidly.
Due to the presence of nitrogen in the air, the reactivity of oxygen decreases and several processes such as corrosion, metabolism, and combustion take place at the proper rate.