Looking past the obvious idiotic aspect of this idea,
I wonder what physiologically effects of breathing a vapor/chemical cocktail, at elevated pressures, you will encounter.
I don't know the chemical makeup of e-cig vapor, and I am to lazy to look it up.
My understanding is that it's unregulated and
no one knows (other than maybe the manufacturers) know what's in various formulations. It's like "trust me" breathing.
It's an incredibly stupid idea in general, but it seems every generation has to have it's own incredibly stupid idea.
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As for the OP's idea, I need to point out that the effects of various gases and chemicals is very dependent on partial pressure, and something that will only kill you over the course of 20 years at 1 atmosphere, may kill you in minutes or seconds at elevated partial pressures. Given that you a) don't know what the chemicals involved are and b) don't know there affect at the surface, let alone at elevated partial pressures, it not just a bad idea, it's basically stupid with stupid sauce on top.
---------- Post added December 5th, 2015 at 07:06 AM ----------
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There is a bit of irony here, as I was giving one of the local dive shop employees crap the other day for smoking (in the designated smoking area at the curb). We discussed in general what a bad idea it was, particularly for technical diving instructors, then joked about a rebreather instructor who smokes about 2 packs a day, which led to a discussion of the wonderful idea of exhaling smoke into the loop so you could rebreathe the smoke through the whole dive.
With none of this being seriously considered for obvious reasons.
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I can also comment on the very brief fad of flavored air back in the early 1980s. Sounded like a great idea, except of course for the unknown affects of what ever you are using for flavor when it's under pressure, which we weren't experienced enough or knowledge enough to even consider as a risk. In practice however, an entire tank of mint flavored air over the course of a 45 to 60 minute dive is enough to put you off mint for months.
Another incredibly stupid idea - that one from my generation.