Is there a certain depth where oxygen becomes toxic?

Answer 1

The answer to this question depends on the oxygen concentration that you are using and, to a degree, your body chemistry. Hal Watts has reportedly made many "bounce" dives on "air" (21% oxygen 79% nitrogen) in excess of 400 feet in sea water. Discounting the narcotic effect of nitrogen, ambient O2 or "air" becomes toxic at around 240 feet in salt water. You should never dive without proper training, and even properly trained Scuba divers would not dive beyond recreational limits (130 ft) without special training. Oxygen concentrations higher than 21%, or enriched air (Nitrox) will have MOD Maximum Operating Depths based upon the specific concentration of oxygen. 100% oxygen is dangerous below 20 feet and, unless you are trained in the use of military rebreathers, you should not be diving 100% oxygen. Technical divers frequently use concentrations of oxygen up to 100% for decompression in stage tanks, but they are not diving on oxygen. Many will undoubtedly realize that I am not distinguishing between 1.6 ATA and 2.0 ATA... Nor have I discussed the 24 hour clock and the cumulative effect of oxygen exposure. If you are still wanting to know the depth at which a specific concentration of oxygen or an exposure to oxygen over time can become toxic, you should take a class in Nitrox or enriched air from a internationally recognized SCUBA agency. Many questions will be answered and you will learn the formulas to determine oxygen toxicity for a given concentration. I hope this helps