***Please help! need relationship advice..ADULTS PLEASE READ?

Hi there...26yr old female here...im gonna make this as short as possible to read..ive been in a relationship with my bf for almost 4 yrs. He is a heavy smoker. He smokes newport cigs as well as weed EVERY DAY. i try to be supportive and not nag or annoy him. I understand its very addictiave habit and hard to quit. I do not want to leave him because of his bad habit. Everytime we are together i am constantly inhaling his smoke from the cigs and the weed. I do not smoke at all. Im not gonna sit here and list 100 reasons why i cant stand it, but what i do know is that im worried about his health..and my health..and i dont want to be around it anymore,but no matter what i do or say..he will not quit. He just says....i have tried to quit and its to hard. Obviously he really enjoys it...so IM EXTREMELY worried that he is never going to quit...and as long as we are together..i will always be around it and im worried i might loose him one day because of it :( PLEASE...ANY ADVICE? IVE tried everything..even his family got him the eletronic cig and he doesnt use it.