Anytime you are inhaling anything other than good O2 it can't be good for the system. Whether it is e-cig or vape juice no matter what anyone says it can't be good in the long run. Our lungs don't respond well to any foreign body, dust, fumes, smoke, etc. Even if the stuff was just water, over time that wouldn't be good either. And even though there is some second hand smoke issues it really does show why pipe smoking is the best option for smokers, no inhaling but still getting Nicotine. Cigars too also better but the mouth contact makes them less "healthy" than pipes.