As a respiratory physiologist, I can tell you that oxygen is essential for life, but it can indeed be harmful in excessive amounts. When too much oxygen is introduced into the body too quickly, it can lead to the formation of reactive oxygen species, or free radicals. These free radicals are capable of damaging cells by interacting with and altering the structure of vital molecules, including DNA and proteins. The process of oxygen toxicity can occur when the partial pressure of oxygen in the body exceeds certain levels, which can lead to issues such as oxygen seizures, respiratory issues, and in severe cases, it can cause cell damage or death. This is why divers and astronauts, for example, are carefully monitored to ensure that their oxygen levels are within safe limits to prevent such toxic effects. In summary, while oxygen is vital for our survival, too much oxygen can indeed be harmful and potentially kill cells or even lead to death due to the destructive effects of free radicals. read more >>

Evidence suggests that pumping in too much oxygen too quickly can strip the molecule of a single electron, creating a free radical. Free radicals, linked to rapid aging, are highly reactive with other molecules, including vital DNA and proteins, the destruction of which can damage or kill cells.read more >>