This raises an interesting question in Halacha (Jewish Law) - assuming we put aside the issue that damaging your body in any way is forbidden and hence smoking shouldn't be allowed at all....
There's an old joke. The non-Jewish neighbour is talking to some friends and says "The Jews have these strange days. On Shabbat they eat in the dining room and smoke in the toilet. On Tisha b'av they smoke in the dining room and eat in the toilet. And on Yom Kippur they smoke and eat in the toilet."
Where does this come from? On Shabbat eating is allowed (indeed it's a requirement) so people can eat in the dining room, but smoking isn't allowed (creating fire is forbidden) so someone who wants to smoke has to do it in the toilet (although one presumes G-D can still see in there!).
On Tisha b'av, a fast day, eating isn't allowed, so people if they want to eat have to do it in the toilet, but they can smoke in the dining room.
And on Yom Kippur, both are forbidden - so, well, you get the idea.
So where does the question come? Well, on Jewish Yom Tov (festival) days, cooking is allowed (with certain restrictions). And there are those who are completely addicted to smoking that, yes, they say cigarettes can be smoked as they are as essential to them as food is. Fine.
But then if that is the case, surely you can't smoke on a fast day, such as Tisha b'av!
Needless to say many observant cigarette-addicted Jews will smoke on both Yom Tov and Tisha b'av. But according to this process, you can do one or the other, but not both!
And as for smoking on Shabbat? I once saw someone make a "Shabbat cigarette". Before Shabbat, they lit a number of cigarettes and put them into a large bottle and let them burn out, filling the bottle with smoke. They then throughout the day could open the lid and suck in the smoke.