How can the air we breathe be so harmful to us, after all isn’t oxygen good for us? Well, we do know from our Enriched Air aka Nitrox class that under pressure can become toxic to our body and cause a host of issues.
We can avoid all of those issues by paying attention to our dive computers and by setting our oxygen levels on our computers correctly. Let me provide an example that actually happen to me of all people. A day before we went to the crater I was showing a diver how to set the oxygen limits on one of my dive computers. This particular computer you can actually set up to 99% oxygen. By the way at that level the maximum dive depth is 13 feet. Well instead of making sure it was set back to regular old 21% air, I must have left it at 99%. Well you can just imagine the grief that the computer was giving me after only 5 minutes of the first dive at the crater. As most of you know that dive is usually between 16 and 25 feet. Well after 5 minutes my computer was telling me that I was approaching my oxygen limit for 24 hours. And after 10 minutes I was way past that limit. I knew I was fine and I knew what had happened. But of course my computer didn’t know that I was fine and actually diving 21% or just regular old air.
Of course I finish both of the dives with the class and one extra for the advanced open water students. At this point I was curious what the computer would actually do. I was definitely on the naughty list as far as it was concerned. But after 14 hours of being out of the water the computer was much happier and allowed me to reset it to 21%. After 3 more dives with the class the computer was showing only 5% of my daily oxygen exposure had been reached.