Scientific studies on air breaks

[Kay Dee]

Every case of oxygen toxicity that I know of has occurred at greater depths with people using incorrect mixes for the depth. It is usually a labeling error.

I know of at least three shallow. One I witnessed at 9m (and not while breathing the 'wrong' gas) and two others reported to me by reliable people.

 

[Kay Dee]

Average PO2 for technical CCR and OC dives usually comes out about the same. It’s not uncommon that the deco at 20’ is as long or longer than the BT, so the 1.6 at 20’ raises the average quite quickly.

I believe - although no first-hand knowledge - that this was the cause of several tox incidences back in the daze (1980s - early 90s) when some folks were diving OC deeper than 66m on air (i.e. running up the 'over 1.6' time clock on the bottom) and then ascending and decoing on oxygen.