I am not allowed to create personal messages, but I am interested in your post. My field is Nutritional Therapy and Chronic Degenerative Diseases. I have never heard anyone suggest that vaping PG or VG could potentially help "wash the lungs clean" of tar juice, but that would be very interesting to me. I am also a smoker (and a hypocrite, apparently,) transitioning to a vape. I have begun making my own "e-juice," as it is more economical, easier to trust, and absent the diacetyl and other toxic or irritant flavorings, so I would be very interested in the results of your inquiries so far if you find something that would seem to be beneficial. Would you please PM or email me at:
My favorite tea for breathing is:
Licorice root, eucalyptus leaf, bitter fennel fruit, Bi Yan Pian, peppermint leaf, calendula flower, pluerisy root, and ginger rhizome.
But I cannot say that any of these are safe to inhale, or how safe and active materials for this application might be extracted.
On a side note, your friend may want to drink some tea. It may or may not help heal the lungs but, I can tell you, licorice root is heaven for cravings.
I would also be interested to pick your brain about these synthetic nicotine salts.