I've been vaping in the Air Force for about 8 months now. As I understand it, The Air Force classifies PVs as tobacco products, and limits their use to "designated tobacco use areas." I work flightline, so there's always lots of people everywhere, and it's not worth the risk of the wrong person seeing me using it in the wrong place, so I just conform. I would be nice to see the branches make a more informed decision however. I do think that the overall health related costs of members' tobacco use could be lowered by incentivizing the use of PVs. One easy way to do that would be to allow them indoors.