lwien said:
THC may be an expectorant, but it is also a lung irritant, so no, I would not say that THC is good for your lungs, even if you vaporize it. Like everything else, it's all a risk/reward ratio that we need to take into consideration.
And keep in mind, that besides a wide variety of cannabinoids, this is just a small portion (probably at very best 15-20%) of material you are also inhaling -- a load of other plant organics and any contaminants present. This includes a wide variety of essential oils, sterols, terpenes, waxes, chlorophyll and its degradation products, sugars/carbohydrates, and any residual water, pesticides, mold spores, dust particles, insects and larvae, bird droppings and enteric bacteria (if grown outside), etc. -- just about everything naturally found in and on the plant except for the cellulose, which will not vaporize.
Obviously, some of these probably 1000s of substances are going to have some adverse effects. Some may also act as congeners and subtly affect the desired drug effects, positively or negatively. And keep in mind, that the very first part of what you inhale with most vaporizers could well include material picked up in the air stream before the herbal material was heated to a high enough temperature to sterilize it. Now, whatever potential herbal vaporization inhalation hazards there may be, these are obviously not a problem in otherwise healthy people (we inhale plant debris dust and vapors as part of the natural environment); and the same inhalation issues (and a lot more) apply to smoking herbal material.
I think it would be incorrect to assert that vaporizing any unrefined/unpurified herbal material is more healthy (physiologically) than not vaporizing it. Similarly, it is incorrect to assert that vaporization is good for you (vs. not vaporizing ground up plant material).