Great read! I am a PG user and can say without a doubt.. I have been vaping for over 7 months, About 1 year ago my chest X Rays showed the start of COPD as explained by my DR ... My chest X Rays taken less than 1 month ago showed clear.. Yes My Dr had to take a second look and was amazed.. I feel that if I would have stopped smoking (cold turkey) my lungs would not be as clear as they are now.. so I do attribute it to vaping.. again I don't just vape I use Inhalers (Drews) Lung juice (I think there are other suppliers that offer juice with herbs also).. I can breath like I was 17 running the 2 mile dash.. no wheezing or coughing.. So in my case vaping has been very good... of course like smoking it is a individual thing not everyone smokes the same nor do they vape the same so studies would very widely after reading this thread I would also be inclined to believe that the PG also helped in the healing of my lungs, don't know but this is my case and the proof is in the X Rays 