Does smoking pot reduce your life exspectancy?

I have smoked since I was fourteen, I am currently eighteen. I have been weed free for 2 weeks this monday. But I was wondering if I go back and become a smoker again will it shorten my life expectancy? I smoke blunts if that makes any difference. Please only answer this if you have some type of real knowledge about this and not just some anti smoker or want to put in your two cents.