let's face it, smoking anything isn't good for your lungs. the only way to get rid of the carcinogens from weed is to use a vape (which burns the thc alone, right? never used a proper one myself, only shitty lightbulb ones). joints and blunts (or if like me you roll spliffs) are harsher on your lungs than a cigarette for sure, of course depending how big you roll, how tight you pack and how much if any tobacco you put in...but who needs a pack of joints to get high? One joint with a half gram or so of good stuff, stoned for a fair while, I don't smoke more than two a day, most of the time just one. so really, while it's more carcinogenic (I'm not even sure if that's been entirely proven?) it doesn't matter because you don't smoke as many joints as smokers do cigarettes
there are studies all over the net about the safety of various smoking devices...there was a really good danish or swedish? one I found ages ago that was useful, but I couldn't find it in a quick search...if you're interested though, look around