Eating requires a bracha rishona, but merely tasting something and then spitting it out without digesting it does not require a bracha (Shulchan Aruch 210:2). This commonly happens when a cook wants to taste something to see if spices need to be added to a dish.
The Magen Avraham (210:9) debates whether or not a bracha is required when smoking "Tabak." On the one hand it is similar to tasting and then spitting out which does not require a bracha being that the smoke is never digested. On the other hand this should be no different than smelling besamim which does require a bracha rishona. Even more so here there is more reason to require a bracha since some people actually swallow the tabak.
The Minhag Yisroel Torah (210) brings down from the K'sav Sofer that based on the shaila posed by the Magen Avraham, 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.
AS, Yerushalayim, 2010-02-02 07:50:15 Is smoking not assur? How could there be a shayla of making a bracha on an issur??Anonymous, 2010-02-02 08:28:02 To AS - Do you make a bracha on candies that are pure sugar and other unhealthy foods? Why do you single out smoking?jj, 2010-03-03 01:08:06 In those days they didn't know it was dangerous. Additionally the danger of cigarettes is the tar and 200 chemicals that are put into todays cigarettes. In those days it was pure tobbaco which isn't nearly as dangerous.SI, Cape Town, 2013-09-09 09:50:43 The correct bracha is "Baruch Dayan Ha'emet".