The bottom line is; your are not doing your lungs right when you inhale anything but air. Vapor is a very healthy form to inhale medication, however you are entering a foriegn contaminant that is not natural to the lungs design. The good news is that since its thc, most of it will be absorbed, with water filtration and quality vaporization devices the level of contaminate to the lungs is significantly reduced. Furthermore our lungs are contaminated all the time because we live in an industrial society, the air we breath is not pure more then likeley dependent on where you live. If you want to ensure that your lungs are not being damaged at all then the only course is to completley cease introducing anything into them other then air. However vaporizing really redces a lot of the problematic harm caused by smoke, and due to the expectorant effect like isaid its good to cough up phegelem, it helps your lungs do so. I was once a heavy medical smoker, and on xrays my lungs were showing black signs, that was 2 years, ago, I've since then have had 2 xrays and both show clear lungs, that the radiologist even went to note "no signs of contaminant" I think its safe to safe vaporizing is okay, but with everything in life, the healthiest option is moderation and being aware of how your going about it, and understanding how your body reacts. Our bodies are designed to recover, and maybe you need to vaporize less chronically and you'll find less discomfort. The mroe chronic the vaporization in my opinion the more irritation one notices. I completely understand where your coming from as even though my lungs have been given a clean bill of health, mine are very sensitive to vaporizing too. I've found that lower temperatures, taking it in between my hits, like not taking a draw from my cloud for at least once every 5 minutes I've noticed i get more out of the medication and tax my lungs less.