Hello @greenrun,
The correlation between smoking and longevity can be explicitly explained as those persons who are biologically distinct. People who are blessed with different genetic variants that enable them to respond differently to "cancer sticks" side effects.
Amongst thousand smokers, only a few are physiologically less susceptible to the arterial aging and carcinogenic effects of cigarette smoke than others.
There is no doubt that the intake of any tobacco products, be it smoking, chewing, or inhaling smoke, of course increases aging of the immune system (and arteries).
The mortality rate among smokers is three times that of nonsmokers, mainly as a result of smoking-related diseases, like vascular, cancer, and respiratory diseases.
Therefore, those persons who are immune to cigarette smoking side effects are biologically distinct persons.
Thank you Boss!