E-cigs release vapor containing various chemicals, usually including nicotine, into the air, requiring others to breath it. Even if it is much less harmful and unpleasant than cigarette smoke it should come as no surprise that hospitals ban their use indoors. Even if a hospital didnt have a policy on this yet, you shouldn't be surprised if someone asks you to take it outside.....just as someone might ask you to take it outside if you brought your sound system into the hospital and cranked up the volume (it might not damage any eardrums but other people using the facility dont want to have to listen to your music). The more valid issue possibly worth fighting is where a hospital has a tobacco-free grounds policy and wants to include e-cigs (or snus for that matter). If you are outside the building, and not standing somewhere that people have to walk right past, its hard to argue that your vaping is inconveniencing or harming anyone else....and if it is helping you to stay off traditional cigarettes it is "pro-health".