(Inspired by Double AA) Based on the Premise (which I may be wrong on) that there are pieces of the actual Tobacco leaves or whatever else is smoked in the inhaled part of the smoke hence there would seem to be ingestion of Tobbaco in the smoking processes. Why is there no Bracha on Smoking?
Original source: http://revach.net/article.php?id=3388 My edited and shortened version
Tasting something and then spitting it out without digesting does not require a bracha (Shulchan Aruch 210:2). This happens when tasting something to see if spices are needed .
The Magen Avraham (210:9) questions whether a bracha is required when smoking.It is similar to tasting and then spitting out which does not require a bracha being that the smoke is never digested or it should be no different than smelling which does require a bracha rishona. Even more so here since some people actually swallow the tobacco.
The Minhag Yisroel Torah (210) brings down from the K'sav Sofer that R' Mordechai Banet, prior to smoking a cigarette, would make a shehakol on another food item with the intent to include the cigarette as well. Should the cigarette require a bracha, the shehakol (an all encompassing bracha) would include it. However the Minhag Yisrael Torah writes that the minhag b'zman hazeh is not to make a bracha prior to smoking.
It seems to me that, regardless of whether bits of tobacco find their way to the stomach, this is obviously not eating in any meaningful sense, and thus would not be subject to a food berachah.
The issue by smoking, as I understand the sources, is less about eating of tobacco micro-particles, and more about whether or not the enjoyment of smoking itself should get a bracha. The gemara in brachos 35A states that the basis for making brachos on food is svara (reason): "one should not enjoy the world without a bracha". Rashi explains that it is basic derech eretz - one should thank hashem (the source of all pleasure) for pleasure one receives. However, this svara opens up a can of worms - why don't we make brachos on all pleasure we get! The ramban explains that chazal only instituted brachos to a very limited category: where the item from which one derives pleasure enters the body and the body enjoys it. The two examples of this in the gemara are eating and smelling.
The question becomes: can we use such a rule to expand brachos beyond the explicit examples in the gemara? Maybe smoking should fit this category - the smoke enters the mouth and smokers enjoy it.
The magen avraham is not sure because he thinks it can be compared to two different cases, one which gets a bracha and one which doesn't. On the one hand, tasting food and spitting it out does not get a bracha (see shulchan aruch 210:2). Maybe smoking should be compared to that (he says that one does not "swallow" the smoke but spits it out). On the other hand, one does make a bracha on smell, and smoking might be comparable to smell. My understanding of this magen avraham (although I admit, it is not entirely clear), is not that he is suggesting smoking is smelling or is eating, but rather he is trying to figure out if smoking, which is neither of those things, should get a bracha based on comparison to that which does get a bracha. The magen avraham (216:1) quotes the ramban's general rule, so he is consistent in that he is open to broadening pleasures which deserve brachos. One could, however, argue that really there is no general rule by brachos, and we only have brachos where chazal instituted them explcitily (eating and smell). If this were the case, then there really is no question. This seems to be the view of Rav Yaakov Emdin (mur uktzia 210, toward the end), where he says that it is pashut that smoking would not get a bracha since it is not at all eating. He takes it for granted that if it isn't eating that it doesn't get a bracha. The mishnah brurah (210:17) paskons like Rav Yaakov Emdin.