I too believe that pipe smoking is less harmful than cigarette smoking especially at my current rate of 3-4 bowls a week and always outdoors to limit "second hand smoke" inhalation. It probably is, but the problem is, that you will never be able to prove it scientifically. You will never be able to design a prospective or even retrospective epidemiological study with sufficient power to come out with a statistically significant result. There are just not enough pipe smokers on this planet.