lets get something straight: anything, anything at all that you smoke will most likely irritate your lungs, especially if you smoke whatever it is you're smoking regularly.
if i smoke wood, it won't be good for my lungs.
if i smoke weed, it won't be good for my lungs.
if i smoke theobromine, it won't be good for my lungs.
smoke is a burning compound entering and charring your cells. you aren't guaranteed to get cancer, but any disturbance of cells like that (such as injuries, radiation, anything that upsets the growth) can give you cancer.