In case anyone might be interested, here is the requirement for compliance of suppliers' marketing materials in this area:
Any statement or implication that exhaled vapor is entirely water vapor must be removed or modified before a supplier's website is accepted for registration on ECF. For example a statement such as, "...and the exhaled mist is just water vapor" is not allowed. It can however be edited to read something like: "The exhaled mist is mostly water vapor", because it may be.
In the absence of any trial to
specifically address this question, we have to rely on the content of three published sources that refer to this issue in general terms, and try to extrapolate some relevance to exhaled vapor. All these articles originate from research in NZ by Laugesen and colleagues.
Ecigarette mist harmless, inhaled or exhaled
http://www.healthnz.co.nz/Portland2008ECIG.pdf
http://www.healthnz.co.nz/RuyanCartridgeReport30-Oct-08.pdf
What seems to occur, from the data presented, is that the
inhaled vapor consists of a high percentage of PG and/or VG, plus alcohol if present in the liquid, plus a small percentage of water, plus a smaller percentage of nicotine and flavors.
The
exhaled vapor on the other hand consists of (simply a guess as there is no specific data available) less PG/VG and more water, plus flavors and nicotine. It is far more visible than its actual mass indicates, in other words, what you can see is something that weighs very little indeed.
The amounts of the non-water constituents in vapor were measured by Laugesen
et al as:
PG / VG - 0.7mg per 'puff'
Nicotine - 0.01mg "
These values were for inhaled vapor. Exhaled vapor has not been tested except for carbon monoxide. He states that, "Exhaled breath after e-cigarette use has been tested for CO only...", showing that a full test of exhaled vapor was not performed.
So it looks as if exhaled vapor is water plus PG/VG, and a tiny amount of flavors and nicotine. The question is whether the mist is mainly water or mainly PG/VG. And - how do you mean exactly? Do you mean - what you can see; or do you mean, by weight? The two might not be the same, for example the visible constituent might be water vapor but that might comprise only 2% of the total mass. Laugesen says, "...the exhaled mist of the e-cigarette is composed of propylene glycol...", which on the face of it seems fairly solid - but (a) due to the context of the rest of the report, he is making a non-quantifiable statement that allows for the fact there may be a considerable amount of water vapor also present, and (b) none of his research *specifically* addressed the exact composition of exhaled vapor.
Until proper research confirms which of the two it is, we would accept that exhaled vapor may have more water than PG/VG or vice versa. For the present we will accept "mostly water" in vendors' marketing descriptions of exhaled vapor - because it may be so, and because we can't prove them wrong. We won't accept "exhaled vapor is water vapor" (or for that matter "...is propylene glycol") because neither can be correct.
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Update 2011-01-15
We located four PDFs with results of some research on electronic cigarette vapor.
http://www.e-cigarette-forum.com/fo...9160-analysis-electronic-cigarette-vapor.html
This research is best described as 'inconclusive', since in none of the four cases were the projects managed correctly or the results presented correctly. However they represent the fullest information we have. The only one that gives any sort of quantifiable results for the vapor ingredients states that mainstream vapor (ie direct from the e-cigarette before inhalation) is 66% water. It seems likely that the water content of exhaled vapor will be higher.
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