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Dive Dry with Dr. Bill

#679: Geezer Gas

I've now used SCUBA for 54 years although I didn't start ocean diving until I arrived on Catalina August 24, 1969, on board the dive boat Golden Doubloon. Prior to that I could hardly say I was a marine biologist since most of my "diving" was in swimming pools and other freshwater bodies.

Back in those ancient days the only gas folks like me could dive was the one God gave us... air. Good old 21% oxygen and 78% nitrogen plus a few trace gases making up the last 1% (no relation to the 1% in terms of wealth... these trace gases have little influence on us). It was hard enough to find sources for that since few SCUBA shops existed in the Chicago area back then. Tanks were often filled at fire stations.

Years ago my friends' children referred to me as an old geezer even though I was just a spring chicken back then. Today I have to accept that label as more appropriate, especially in view of our feeling back in the 60s that we'd never live past 30. Fortunately we were wrong (at least the ones of us who survived that era).

So last weekend I made it official and became certified to dive on "geezer gas" thanks to my dive instructor friend Carrie Ewbank. Many had offered to certify me, but my upcoming return to Palau for about 75 dives suggested it was time to take Carrie up on her offer.

So what is "geezer gas" you ask? Some divers object to the phrase, but I don't. It is one of several nicknames for enriched air gases or Nitrox. An even stranger one is "voodoo gas" (not to be confused with voodoo economics). Technically Nitrox refers to any mix of breathable gases that contain different percentages of oxygen and nitrogen. Most mixes involve oxygen levels greater than air. The most common mixes are 32% and 36% oxygen. Given improvements in technology, many dive shops now offer Nitrox including SCUBA Luv.

Why dive Nitrox? The simplest explanation is that increasing the percent of oxygen in the mix results in a lower percent of nitrogen. The less nitrogen in the gas you breath while diving, the less chance of nitrogen bubble formation in your bloodstream and possible decompression sickness from it.

Many divers say they feel far less tired when doing repetitive dives on nitrox than on air. While I'm in Palau, I will be doing three dives a day then lecturing on coral reef ecology at night. I've been known to put a few in the audience to sleep, but it would hardly be appropriate if the lecturer started snoring!

Nitrox has had a controversial history in the diving community. As early as the 1920s or 1930s German manufacturer Draeger made a Nitrox based air delivery system. In the 1950s US Navy divers studied enriched air for use in military diving and in 1970 it began being used by NOAA divers. In the early 1990s many organizations felt Nitrox was unsafe and banned its use but by the middle of that decade it was becoming more accepted.

Although diving a gas mix with less nitrogen reduces the possibility of bubble formation, the increased oxygen content involves new potential hazards. Mixes with high oxygen content may cause fire and explosion although safe handling procedures are followed today.

A diver diving Nitrox does incur a risk of oxygen toxicity. Yes, wonderful O-2 can be toxic and even result in death. Divers on Nitrox have to be careful of the depths they dive. A few years ago I repeatedly dove to 200 feet on air, which I considered an acceptable risk. Diving Nitrox will restrict me to depths of about half that to avoid the toxic effects of oxygen.

Diving different blends of Nitrox requires a diver to be able to make a number of different mathematical calculations and/or use a special set of tables for diving the mixes. I must admit I had a little trouble becoming fluent with the tables although the math was easy peasy. Good Nitrox capable dive computers make this all much easier, and I always dive with two of them for added safety in case one fails.

So while in Palau I will become the subject of my own scientific investigation into the effects of Nitrox while diving fairly intensely for five weeks in one of the most beautiful places in the world. Will it make me feel less tired at the end of the day and ensure that I don't bore my classes with my snore? Time will tell.

© 2016 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. You can also watch these episodes in iPod format on YouTube through my channel there (drbillbushing). Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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Tanks with air, 32% and 36% Nitrox, and Nitrox RDP dive table; alternate Nitrox nicknames and the old geezer himself!

This document maintained by Dr. Bill Bushing.
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