Oxygen is a very strong oxidant. It is necessary for mitochondria, the ‘energy plants’ of our cells to work and ‘burn’ glucose to get energy. High doses of it oxidize and damage molecules and tissue of our body. Our body is constantly trying to get rid of the ‘free radicals’ oxygen atoms available to interact, bind and oxidize other molecules, that will result in long-term damage. The optimum percentage of oxygen that we breathe normally is very less and if we breathe the pure form, it will alter our blood gases, resulting in imbalance in our body’s pH level too.