Put match to tobacco and create carcinogens. The degree of health damage is mostly dependent on your gene pool. Sucking the carcinogens into your lungs is risky. Only allowing them to enter your system through the mucus membranes of the mouth and nose is most likely less unhealthy. Smoking is a vice for those those willing to measure risk/reward and make a conscious decision to risk their health. Smoking is not something the risk averse should even consider as such risk will lurk in the back of the mind and prevent the full enjoyment of the pipe, cigar, cigarette or what have you. The pipe is, I believe, proven to be less risky, with regard to future health problems. But, if you are young and invincible, the future is of less importance than the here and now.
I always suggest, when asked, that a prospective smoker weigh all of the known risks before making a purely selfish decision. We all should have a wee vice but, weighing the risk/reward is only due diligence.