smokers by UCSF and University of Alabama showed that those who only smoke a few joints a week actually had stronger lung capacity and external blowing force than non-users. A 2005 UCLA paper also shows that marijuana smoke might actually help to PREVENT lung cancer. Unlike tobacco, which contains nicotine and is a known carcinigen, marijuana contains cannibinoids and THC, which seem to discourage cancer. It is also impossible to die of an overdose. Put that in your pipe and smoke it.