Breathing a pure oxygen atmosphere over a period of time can lead to carbon dioxide poisoning. The red blood cells get so overloaded with oxygen molecules that they can't take up the waste carbon dioxide the body produces and move it to the lungs where it can be exhaled.

If oxygen can be that poisonous, then it only makes sense that it can't be beneficial to breathe it in any quantities at all! So it only makes sense to avoid breathing oxygen!!

Don't say you haven't been warned!!

Don Firth