In USA, mostly everywhere smoking has been prohibited for a pretty long time now. You cannot smoke in buildings, in libraries, in many city parks and bus stops, whilst dining or partying outside on a patio of a bar/nightclub in many cities, private apartments in some cities, anywhere on campus of pretty much every major research university (prohibition usually comes as a condition of "compliance with external cancer research funding requirements", and goes as far as not even providing any designated smoking areas at all anywhere on the whole campus) etc.
However, with the proliferation of electronic cigarettes, it's been increasingly common that someone always thinks that it's OK to smoke in a confined space next to you. Recently, I noticed that the smokers don't even refer to this as "vaping" anymore, but call it straight for what it is — "you smoke?", can be overheard as someone shows off their electronic equipment within a no-smoking area.
It is unclear what's the rationale for such decisions by some members of the public (considering that nicotine is highly addictive), however, a few years ago, I came across a list of smoke-free laws, where sometimes electronic cigarettes were specifically outlawed, whereas other times they were never mentioned; this has also been common on some no-smoking signs at some establishments, which sometimes expressly prohibit electronic cigarettes.
Casual research showed absolutely zero jurisdictions where electronic cigarettes were specifically legislated as being allowed — they're always either expressly prohibited, or not at all mentioned. Logically, as nicotine is widely known to be highly addictive, it would seem reasonable to expect that the prohibitions aren't merely meant to address the risk of cancer.
From the legal standpoint, is it at all reasonable to expect that smoking electronic cigarettes is prohibited by generic "no smoking" laws and/or signs, or would it be legally allowed unless certain other conditions are met as well?
Does it at all matter that there is no known jurisdictions that allow one type whilst prohibiting the other? E.g., it's basically always the case that either both electronic and traditional cigarettes are outlawed, or there is simply no mention of the electronic ones in the laws and/or the signs.