Claiming that vaping is orders of magnitude safer than smoking, without proof, is still highly irresponsible. We simply don't know how safe vaping is.

The history of making safety claims about addictive products is quite fraught with delibratly misleading and false statements. Please take care not to exacerbate this.

Why do you say this so categorically?

"...[R]ats were nose-only exposed to filtered air, nebulized vehicle (saline), or three concentrations of PG/VG mixtures, with and without nicotine...Compared with vehicle exposure, the PG/VG aerosols showed only very limited biological effects with no signs of toxicity."

https://www.ncbi.nlm.nih.gov/pubmed/28882640

Propylene glycol has been used as a carrier for pulmonary inhalers as well as in food and cosmetics for decades.

> Propylene glycol has been used as a carrier for pulmonary inhalers as well as in food and cosmetics for decades.

Propylene glycol was deemed safe for oral consumption, not inhalation. I have not seen any sources of information indicating its use in pulmonary inhalers, do you have some sources you can link?

See, e.g., https://www.ncbi.nlm.nih.gov/pubmed/12425745

It's also listed as approved as an inactive ingredient by the FDA, including for inhalation:

  PROPYLENE GLYCOL | RESPIRATORY (INHALATION) | LIQUID   | 57556 | 6DC9Q167V3 | 10%w/w
  PROPYLENE GLYCOL | RESPIRATORY (INHALATION) | SOLUTION | 57556 | 6DC9Q167V3 | 25%w/w