From Chapter 1:
It may further be added that though the use of tobacco was known and practised on the continent of Europe for some time before smoking became common in England—it was taken to Spain from Mexico by a physician about 1560, and Jean Nicot about the same time sent tobacco seeds to France—yet such use was exclusively for medicinal purposes. The smoking of tobacco in England seems from the first to have been much more a matter of pleasure than of hygiene.

From Chapter 5:
At the time of the Great Plague all kinds of nostrums were sold and recommended as preservatives or as cures. Most of these perished with the occasion that called them forth; but the names of some have been preserved in a rare quarto tract which was published in the Plague year, 1665, entitled "A Brief Treatise of the Nature, Causes, Signes, Preservation from and Cure of the Pestilence," "collected by W. Kemp, Mr. of Arts." In the list of devices for purifying infected air it is stated that "The American Silver-weed, or Tobacco, is very excellent for this purpose, and an excellent defence against bad air, being smoked in a pipe, either by itself, or with Nutmegs shred, and Rew Seeds mixed with it, especially if it be nosed"—which, I suppose, means if the smoke be exhaled through the nose—"for it cleanseth the air, and choaketh, suppresseth and disperseth any venomous vapour." Mr. Kemp warms to his subject and proceeds with a whole-hearted panegyric that must be quoted in full: "It hath singular and contrary effects, it is good to warm one being cold, and will cool one being hot. All ages, all Sexes, all Constitutions, Young and Old, Men and Women, the Sanguine, the Cholerick, the Melancholy, the phlegmatick, take it without any manifest inconvenience, it quencheth thirst, and yet will make one more able, and fit to drink; it abates hunger, and yet will get one a good stomach; it is agreeable with mirth or sadness, with feasting and with fasting; it will make one rest that wants sleep, and will keep one waking that is drowsie; it hath an offensive smell to some, and is more desirable than any perfume to others; that it is a most excellent preservative, both experience and reason do teach; it corrects the air by Fumigation, and it avoids corrupt humours by Salivation; for when one takes it either by Chewing it in the leaf, or Smoaking it in the pipe, the humors are drawn and brought from all parts of the body, to the stomach, and from thence rising up to the mouth of the Tobacconist, as to the helme of a Sublimatory, are voided and spitten out."