It gets pretty confusing when cannabis itself is thought to have anti-cancer properties and the actual amount and temperature of the smoke is much less than that of tobacco. Yeah breathing in any smoke is not good for you, but is it like smoking a pack of cigarettes? Or is it like enjoying a campfire and breathing in a small bit of smoke? One is profoundly bad for you, the other is of such little concern that nobody should be worrying about it unless they have serious lung conditions.