Sensationalist news articles like this tend to run rampant as they attract a ton of, mostly negative, attention and views. Headings like “Second-hand smoke from e-cigarettes may be harmful to your health” mislead readers, many of which include politicians and lawmakers.
While we won't argue against the studies that have found trace amounts of nitrosamines and VOCs in the electronic cigarette liquid, exposures from the vapor fall well below the threshold concern for compounds with known toxicity. Further studies have shown second-hand exposure to nicotine in e-cig vapor to be nonexistent. Any amount exhaled would be so minute that it would not have an effect on bystanders, as the vapor dissipates within seconds as opposed to minutes for smoke.
As I've discussed in the past, electronic cigarettes already contain a tiny, barely detectable fraction of the chemicals found in traditional tobacco cigarettes. They also have been shown not to contain any of the toxins in the amounts found in tobacco cigarettes and that they deliver very little nicotine in the vapor. So, given that the vapor already proves little, if any, danger to the actual user, any danger to bystanders by the exhaled vapor would be negligible.
Additionally, tobacco cigarettes create “side stream smoke,” which is the smoke that comes directly from the end of a lit cigarette and the smoke lingers in the air and travels a fair distance from the smoker. Electronic cigarette vapor does not behave in the same manner as tobacco smoke. There is no vapor produced by the device until the user activates it by inhaling, so no “side stream vapor” is created and the vapor dissipates very quickly.
Furthermore, the Inhalation Toxicology study I've cited in regards to public health published also showed that neither active nor passive vaping has any acute adverse effects on lung function among adult subjects.
In the event that a bystander would pass through the vapor, since it doesn’t contain the irritating toxins of tobacco smoke, it would likely be barely detectable beyond the faint scent of the flavor and only for a fleeting moment. But just because it may be safe for bystanders to inhale your passive vapor, doesn't give you the right to go around blowing clouds in people's faces. Use some vape etiquette and be respectful of your surroundings when in public. Unless you're at a vape meet or outdoors, you might want to leave your sub-ohm builds at home.