Dr Karl of the ABC science show (Australia) …
Back when I was in my 20s, I foolishly took what is probably the most dangerous and addictive drug known to the human race — the one that kills more people than any other drug. Yup, for a few years, I stupidly smoked cigarettes.
I thought that by smoking roll-your-own cigarettes, or ‘rollies’, rather than factory-made, I was taking a healthier (or at least, less harmful) pathway. I was so wrong.
Unfortunately for the (usually poorer) people who tend to smoke rollies, they are both less natural and more harmful. In factory-made cigarettes, the additives make up about half-a-per cent of the dry weight of the tobacco. But in the rollies, the additives are about 18 per cent of the dry weight. In other words, rollies have about 38 times more additives than factory-made ciggies.
But the good news
If you quit smoking before middle age, you reduce the risk of lung cancer by 90 per cent. Within two to five years of giving up smoking, your risk of heart attack and stroke drops significantly. And after 15 years of not smoking, your risk of stroke is the same as if you had never smoked.
http://www.abc.net.au/science/articles/2014/07/22/4050221.htm