"What is known is that The National Institute for Occupational Safety and Health lists propylene glycol as an inhalant risk and recommends immediate fresh air if the chemical is inhaled"
The same thing is claimed for many common compounds (including water).

The fact that e-cigarettes do not separate nicotine from "the oral fixation" is what has kept me from smoking tobacco for the past 3 years.  I used Wellbutrin, patches, gum and other "approved" methods to try to quit smoking 1.5 packs a day with no success whatsoever.