We cannot imagine life without oxygen as it is the sole element responsible for life on earth. Without O2, our planet would not be inhabitable for humans and animals. Oxygen is the most essential element of the lifecycle ecosystem. All the plants, animals and other living beings require O2 directly or indirectly to survive on this planet.
But as the law of nature has it, the excess of anything is bad. Have you ever imagined that if there is excess O2 in the human body, what will happen? Will we be healthier or will there be any side effect of the same? The answer is that excess oxygen will only harm our body and not do any good for it.It will lead to toxicity in our body and symptoms often include nausea, vertigo, altered behavior, rigidness of muscles and convulsions. It may even lead to permanent damage of cells in our tissues leading ultimately to the death of a person.
The toxicity basically affects the central nervous system and prolonged exposure to the same may lead to damaged brain cells. This type of risk is often associated with scuba divers as they get exposed to increased levels of oxygen at varied pressures underwater. This is the reason why they are advised to move down to shallower depths so that the pressure effect of O2 intake reduces and makes it safe for them to breathe.
The amount of risk that one can take while breathing pure O2 is measured by OUT or oxygen toxicity units. One O2 toxicity unit is equivalent to one minute of pure oxygen intake at sea level or ground level air pressure. Professionals like scuba divers and related job workers are initially advised to expose themselves to not more than 615 units of OUT per day. This count is reduced day by day as continuous exposure to the oxygen increases.