I get what your saying. Even if your math is off or dead on. But, your basis is off of one cigarette or device.OSHA
There is no limit (PEL) for PG --> Chemical Sampling Information: Propylene glycol
The Limit for Nicotine is 0.5mg/m3 --> Nicotine
Form this table --> Electronic Cigarette | E-Cigarette | E-Liquid - Density of Nicotine @ 24mg --> 0.16mg per puff.
From this forum on nicotine measurements --> http://www.e-cigarette-forum.com/forum/nicotine/3285-nicotine-measurements.html We have absorbtion somewhere between 80-98 %, lets say 90%. This leaves 10% to be exhaled. This means of the 0.16mg inhaled, 0.016mg is potentialy exhaled per puff.
Let's say a room is 3mx4mx3m this gives 36m3. 36m3 @ 0.5mg/m3 --> 18mg for this room or 1125 puffs. (Fully sealed room no ventillation)
It is unlikely that the nicotine from an e-cig would exceed the OSHA PEL in a normal environment.
(In a study in St Louis in 19 establishments, Nicotine (in Second Hand Smoke) from regular cigs did not exceed OSHA guidelines).
My maths may be out, so please check for yourself.
So, how likely is it going to be just one? If they allow this one employee to do this....would they not allow all? So now the equation has a larger variable.
Anyway, not likely this will ever happen thanks to the new report the FDA has just released. Brace yourself for the ban....oh, your in the UK. Lucky son of a gun.