A small study done by The Center for Tobacco Control Research and Education at The University of California, San Francisco, "suggests that e-cigarettes don't actually help people to quit smoking." However, of the 949 smokers in the study, only 88 used e-cigarettes, causing the study's researchers to "admit that their findings should be viewed with some caution."
World Science reports "They also found that e-cigarette use was more commmon among women, younger adults and people with less education." Last year, the US Centers for Disease Control reported e-cigarette use more than doubled among U.S. middle and high school students from 2011-2012. The lack of solid research, potential youth market, and abundance of caution have had anti-tobacco activists and researchers pushing for a ban on advertising of e-cigarettes.
NPR has a recently story about "vaping" (using e-cigarettes) indoors and in the workplace.
If you smoke, have you been able to cut back your smoking or quit thanks to electronic cigarettes? If you do not smoke, does it bother you that others use e-cigarettes indoors?
We know the ecig vapor when exhaled contains a trace of nicotine (in an amount less than you'll find in a baked potato)...
This is still being investigated.
Not really. It's mostly people who are apparently ticked off that someone might not have to suffer to avoid the bad effects of smoking doing the 'tests' over and over until they get the result they want.
As for why there are people who object so strenuously to e-cigs (even when used in one's own home), I don't know.
Here's a good comparison of various sources of nicotine (in non-smokers) See table 1. Quick summary, a good Italian meal can have days worth of second hand nicotine in it.
The part of cigarette smoke that causes the second-hand problems is the tars and particulates, both absent from e-cigs. It appears that those are the parts of cigarette smoking that cause the problems for the smoker as well. There is a possibility that the nitrosamines and other tobacco alkaloids may be a problem as well, but those are also absent from e-liquid (at least to the degree that they are absent from the FDA approved nicotine inhalers).
As for the propylene glycol, it is an approved food additive and in the UK they're considering introducing it as a mist in hospitals to cut down on hospital acquired infections.
Given that, there's really not much reason for concern. Especially compared to the entirely untested novel chemicals found in a typical office environment.