Earlier quoted context omitted.
They're still not as bad as ammonia and smoke. Edit: It hit me that over the next few decades they are probably going to invent some really nasty things to put in vapes, like they did with cigarettes (that were made to be a lot worse than the "mere" nicotine and smoke inhalation of tobacco smoking), so don't read this in 20 years thinking that people in the past thought whatever they're doing in the future is safer t…
Also, at least in the US, the vehicles (solvents) are unregulated, as are the heating devices (I have been told by some vaping friends that they like the "toasted" effect at the end of a long pull, which is the polymer heating, fracturing, and crosslinking. Ugh. PEG is a common vehicle; some molecular weights are so safe they aren't even regulated (called GRAS -- "generally regarded as safe") and some are quite toxic…
To be clear I find this absolutely horrifying. As someone with chronic respiratory limitations, it is distressing to see people damage themselves this way. It is their right, but you can't make me like it.
My aunt smoked heavily, she always said "I might as well enjoy my life, even if there are fewer years of it" or something like that. The problem with that is that you lose capacity to enjoy life and then you generally die horribly. I know there are exceptions to this - smokers with no severe impairment - but they are relatively few.