I'm afraid your idea will never happen for lots of reasons. Why? Well, without getting too technical, these are the main reasons.
Firstly, there's the issue of oxygen gas pressure. Increased pressure speeds up the toxic effects of oxygen. The air we breathe contains 21% Oxygen but normal activity in humans requires only a minimum of 19% oxygen. Breathing up to 50% oxygen at normal pressure produces no symptoms, but pure oxygen has caused oxygen poisoning at atmospheric pressure in as little as 5 hours. Poisoning manifests itself as dizziness, burning in the nose and throat, fatigue, joint pain, numbness and tingling, headache, cough, palpitations, nausea, vomiting sore throat, fever, possible convulsions, mood changes, vertigo, twitching and lots of other unpleasant symptoms. The main problem however is pulmonary toxicity, which shows as decreased vital capacity and substernal pain. Regular breathing of 50% to 100% oxygen, even intermittently, over a prolonged period can cause lung damage.
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