I was looking online for my oh and found this:
"The 'smoke' that you see with an e-cigarette is not actually smoke at all. It is a mist that is produced by a battery powered atomiser built into the e-cigarette. This mist is created from a liquid that usually contains small amounts of nicotine, propylene glycol, flavouring, and water. The atomiser turns this liquid into a mist that can be inhaled through the e-cigarette's mouthpiece, thus aiding in the simulation of real smoking.
They may not be the completely safe alternative they are painted to be. Some anti-smoking organizations claim that because manufacturers are not required to disclose the contents of the vapor or the liquid before it is vaporized, that it can vary from perfectly harmless to almost as harmful as cigarette smoke. Some studies have shown various levels of formaldehyde, acetaldehyde, and nicotine in the vapor that is emitted. Because the e-cigarette is currently unregulated, these groups argue, the safety claims of manufacturers and retailers should be taken with a grain of salt."
So I won't be allowing my oh to smoke it around our newborn daughter. Especially in the room as she's being delivered/just been born!! I'd also be quite annoyed if someone smoked one on the ward to be honest, whether hidden from view or not.