According to Dr. Salimpour, the negative effect of smoking on the penis is the same as the effect of smoking on heart. This is a blood vessel damage, which makes blood flow obstructed.
Basically this is the effect of elastin, the elastic connective tissue protein and allows tissues in the body to get back into shape after stretching or contraction. In this case, elastin affects the ability of penile erection.
Dr. Salimpour explained, elastin can stretch like rubber. This is what happens to the penis as a result of increased blood flow.
Smoking can damage body’s ability to do that, so it could affect the size of the penis and erectile ability. But researchers could not determine how many cigarettes can damage elastin and shorten the penis size.
Would you still smoke after reading this? Decide yourself to stay long or short. =D
Credit to http://medicmagic.net