I have been asked recently about the electronic cigarettes people have been smoking as a replacement to tobacco based cigarettes.
These electronic cigarettes are not good for the voice. They are filled with an ingredient called "propylene glycol, a type of antifreeze."
Research suggests that when this ingredient is heated it vaporizes. When inhaled this ingredient encourages the vocal folds to become dry which can result in irritation of the whole vocal tract.
I personally would not recommend these electronic cigarettes especially as there are so many now on the market and insufficient research out there. If, as a temporary measure you are able to give up smoking then perhaps (short term) they may be a good thing but know that dependency on anything long term eventually becomes a crutch with its own problems.
For those looking at giving up smoking I would suggest NLP (Neuro-linguistic programing) or in some extreme cases hypnotherapy. Or simply educate yourself on the damage of smoking until you have enough evidence that tobacco is causing damage and be motivated to give up naturally.)