The devices look to my eye to be suspiciously close to a dispersal device for chemical or biological weapons just as they are. With a fully charged battery, so

The devices look to my eye to be suspiciously close to a dispersal device for chemical or biological weapons just as they are. With a fully charged battery, some modifications, and some TATP in place of the propylene glycol, they would also make a decent fuselage-breaching bomb. I could see how they might be considered a security risk. I have heard about vape-battery explosions, just as I have heard about cell phone and laptop battery explosions. I think they could easily be checked in baggage with the same precautions as a firearm. Battery out, fluid reservoir empty, and in a flight-approved, locked container. That said, I was on a cave tour once and some jackass was vaping inside the cave. The guide reminded him "no smoking" and he kept on puffing, explaining, "I'm not smoking. It's a vape." It was already too late to remove him from the tour. People didn't ban cigarette smoking specifically because of the cigarettes. It was because it was the most common means for people to blithely pollute the local air. Vape fluid might be less overtly toxic and more pleasant-smelling than cigarette smoke, but that doesn't mean I want your candy-flavored solvent precipitating out of the air onto my clothes. When you're in an enclosed space without openable ventilation windows, like a cave or airliner cabin or elevator, don't smoke, don't intentionally fart, don't take your shoes off to air out your stinky socks, and don't vape.