My first dives were in Canada at a very safe 1.5ata. I did 40dives. My second and third set of 40 dives were both at 2.4ata. My current home chamber will go way beyond what is necessary,it came from a burn unit in a hospital. I ususally dive at 2.4ata. I generally start my dives at 1.8ata because I have been diving for a while now. Some clinics recommend 1.5ata others 2.4ata. An atmosphere is 33ft, at sea level you have an atmosphere and to get to 1.5ata you add 16.5ft. I believe you can certainly gain benefit from any oxygen under pressure. I would like to give you more detail. I'll pm my number if you have further questions. Di