The information & links posted at the top (with numerous scientific references provided at the sites linked) are result of several debates I initiated in medical & nootropic (smart drugs) forums over the last couple years. Dozens of knowledgeable, bright researchers and graduate students in medical & biochemical fields, including doctors and researchers specializing in health effects of tobacco smoke, attacked my statement "Smoking is good for you" with everything they knew. Months long debates unfolded, arguments were offered, papers were brought up and discussed in depth. Amusingly, the strongest scientific experiments they brought up, appearing to show direct harm from tobacco smoke, turned out upon more careful reading (beyond the antismoking spin in the abstract & introductions) to demonstrate exactly the opposite -- the smoking animals live longer (~20%), while remaining sharper and thinner (by ~15%) into the old age, than non-smoking animals (another one here or here or here or here).
By the time those debates wound down, not only could none of these bright, knowledgeable folks produce a single scientific result demonstrating that tobacco smoke causes any harm at all to the health of smokers (let alone of non-smokers), but they could not name a single other substance, natural or synthetic, with as potent and as numerous therapeutic, protective and life-extending benefits as tobacco smoke. Nothing comes even close to this ancient biochemical miracle.
Ironically, some health conscious readers of those threads, who were strongly against smoking initially, started smoking after following up and checking the scientific references (or another here). Others, such as one smart woman mathematician, started their own sites on the theme "Smoking is good for you" (others here and here) and one moderator, who was ridiculing the idea initially, came back few weeks after the debate in his forum ended, acknowledging that he went out checked the references provided, then checked many of his own, and was left 'scratching his head'.
You can check one of the earlier such debates in a nootropic forum (part of imminst.org), later one here, or in another nootropic/health forum, or one in Dr Siegel's blog (medical doctor, university professor at BU & leading tobacco control expert; another one here)
In brief, all hard science of tobacco smoke (animal experiments, lab research at biochemical level, randomized human trials) supports position 'smoking is good for you', while the antismoking "science" (which was initiated by Nazis in 1930s), after nearly eight decades of intense research and vast resources spent, could not move beyond statistical correlations on non-randomized samples (self-selected subjects, not unlike web polls) i.e. they keep pointing out to this day that such and such diseases are more common among smokers. Duh. Namely, that kind of correlations on non-randomized samples, no matter how strong, are equally consistent with harmful or therapeutic/protective role of tobacco smoke. You need hard science to untangle the causal web behind such correlations. For example (more examples here), people who use respirators have shorter life expectancy than those who never used respirators, while former users of respirators fall in between (the same kind of associations hold for use of tobacco). Does that imply that respirators shorten lifespan?
Antismoking is enormously profitable scam masquerading as science (i.e. a typical junk science), largely produced and paid for by pharmaceutical industry. In return for its investments in battling this ancient medicinal plant (few billions every year for antismoking junk science, for creating and financing "grass roots" antismoking & diseases front groups, in bribes to politicians and "health" bureaucrats, buying antismoking laws and regulations,...), the big pharma profits not only from selling nicotine replacements and other smoking cessations products (which make them 5-7 billions annually), but vastly more from tens of millions in additional cases of Alzheimer's, Parkinson's, asthma, allergies, schizophrenia, depression, anxiety, ADHD, autoimmune diseases, obesity, diabetes,... all requiring years or decades of expensive drugs, and all largely result of frightening public away from this ancient medicinal miracle that has no equal, tobacco smoke (e.g. see some of the enumerated therapeutic benefits acknowledged by none other than pharma sponsored antismoking researchers here).