I located a comment I wrote in an earlier post from several years ago. Copy and paste is much quicker.
Here is the main reference to the issur psakim against smoking. The sefer is called “Chaim Lelo Ishun” written by Rav Yechezkel Aschayk, published in Eretz Yisroel several years ago (publication date is missing). The letters of haskamah are open and specific. The haskamos are from: Rav Shteinman, Rav Moshe Shmuel Shapiro, Rav Michel Yehuda Lefkowitz, Rav Shmuel Halevi Wosner, Rav Nissin Karelitz, Rav Yerachmiel Gershon Edelstein, Rav Boruch Dov Povarsky, Rav Matisyahu Salomon, Rav Shimon Bedny, and Rav Yitzchok Zilbershtein. The other names listed in my previous are quoted in the text of the sefer. Most include the exact language. There is also a letter (dated Menachem Av 5764) that concerns the issur to begin the smoking addiction signed by Rav Moshe Shmuel Shapiro, Rav Michel Yehuda Lefkowitz, Rav Aharon Lein Shteinman, Rav Shmuel Auerbach, and Rav Nissim Karelitz. Rav Elyashiv added his signature to that letter. It is true that this letter addresses the issur to begin smoking, but it also states clearly that smokers must wean themselves off of it, and should never smoke in public places where it can bother others. However, in contrast to an earlier comment, this letter does NOT state that it is muttar to continue smoking because it is a tzorech. I request a reference to such a statement from Rav Elyashiv.
I also call attention to an earlier sefer “Pe’er tachas Efer” that addressed the issur against smoking.
There is also a lengthy psak about the issur against smoking issued by the RCA. This psak discusses all earlier teshuvos from poskim on the subject, including the parameters of “Shomer psoyim Hashem” which was mentioned in one psak from Rav Moshe Feinstein. This RCA psak is available online.
yekke2: There is a serious problem with your logic. Basically, the smoker needs to recognize a psak halacha that conflicts with his personal desire, and their negius is that it should be muttar. There is absolutely no excuse to make conclusions that account for negius. That is called מגלה פנים בתורה שלא כהלכה. That is why a dayan who accepted a bribe is guilty even if he paskens in favor of the other side. You cannot create a halacha, then look for excuses to justify it.
Reb Moshe’s famous tshuvah is misrepresented so easily and so often. He NEVER said smoking is muttar. He only stated that if someone can’t stop, it is not an issur of לפני עוור to give him a light if requested. That is also dated, and obsolete (according to Reb Dovid), as the information of health risks at that time (very early ’60’s) was much more limited than what we presently know. Now, today’s smokers probably began smoking sometime after the psak from, Reb Moshe, when he openly stated that no one should start (not just בעלי נפש).
Lastly, the fatty foods and coke you mentioned are only problematic if ingested to excess. Otherwise, our bodies are well equipped to handle these things. And there are issues with anything to excess. Every single cigarette shortens life, and inflicts medical damage to the body. That is documented in the scientific literature. That is why poskim have specifically dealt with the “single cigarette” issue, and proclaimed the issur as extending to that, not just the regular smoker. Refer to the sefer חיים ללא עישון referenced above. In fact, find the sefer and study it. After that, the naysayers about smoking will no longer appear to be addicted to ambiguity.