smokin nethin is not good for ur lungs. period. the chemicals is commercial cigs r much more dangerouse and unhealthy then those in weed. yes weed does contain carcinogins (sp) but nowendays just bout nethin does. its the type and level of the chemicals that is the problem. weed dosnt have very high or very dangerouse varients of these. in terms of lung damage, i kno i have found i lose my breath faster playin sports after a couple days of light but constant smokin (a joint a day for maybe 3-5 days) but within a couple weeks of not smokin i feel i am basically back to normal. life is full of ways to hurt and kill urself. its bout choosin which ways u wanna do it.