The only things our lungs are rated for, is pure Earth air. A mixture of nirogen and oxygen and etc. That's it. Add smoke or vapor, and performance and quality goes down. Is it inherently BAD for you, yeah probably. Is it dangerous? Might be, who knows. All we know for sure is that it isn't good for you. How not good it might be, is still subjective at this point until long term case studies can be made.