Cigarette smoking is a test case for a Jewish legal (halakhic) critique of toxicality. Tobacco exemplifies the business with a profitable technology that happens to cause unintended harm as a side effect.  As a business practice that poisons people, the tobacco industry is an exaggerated paradigm for many lesser environmental and occupational toxic risks. Cigarette smoking and other health risks were discussed in comments to a post on marijuana and addiction  by Rabbi Gil Student at Hirhurim. The comments discussed whether an individual Jew should be prohibited under Jewish law from smoking cigarettes. The Hirhurim discussion focused on the rulings (psaq) of the late R. Moses Feinstein, who declined to prohibit smoking in responsa in 1963 and again in 1981.
At the outset, I'd say that the comments miss a crucial aspect of the halakhic status of smoking in Orthodox Judaism. Rabbi Feinstein and other halakhic authors forbid, in effect, smoking from synagogues and study halls (batei midrash). By implication, then, there is a halakhic consensus that smoking is prohibited in all indoor spaces shared with non-smokers.  This consensus adds greatly to a hermercurial critique of environmental and occupational hazards.
Smoking can be prohibited as self-endangerment (ushmartem meod et nafshoteichem). So argues a few authors before R. Feinstein's first psaq, as well as R. Eliezer Waldenberg afterwards . However, Rabbi Feinstein argues that smoking is exempt because many people engage in it (dashu beih rabim) and, hence, smoking is one of those accepted practices for which “the Lord preserves the simple” (shomer peta'im Hashem).
R. Feinstein also argues in 1963 that many other great rabbis (gedolei Torah) have smoked. Mycroft argued that “he wouldn't say something is assur that Rabbanim have been doing for centuries.” However, it’s not clear why R. Feinstein relies on this argument. Does he view these past practices as a legal precedent (ma-aseh rav)? Does he believe that earlier rabbis had an inspired capacity that outweighs medical evidence (da’as Torah)? Does he want to avoid harming the reputations of past and current colleagues? In his 1981 ruling, R. Feinstein speaks strenuously against smoking as an inappropriate and excessive desire (ta’avah). [Noted by Literati.] Also, as I belatedly commented, addiction to smoking is arguably forbidden by R. Feinstein explicitly. (Contra the original post R. Student. See , below.)
Many commenters criticize R. Feinstein for not prohibiting tobacco smoking under Jewish law. These criticisms include:
(a) Personal bias. Some claim that Rabbis are biased due to their personal smoking. This claim itself is said to be disrespectful or, alternatively, such bias irrelevant, because all psaq (Jewish law rulings) has a subjective aspect. I would add: even were it historically and psychologically “true”, this claim of bias by a halakhic authority does not invalidate the ruling. [Under Jewish law, there are more extreme conflicts of interest that may invalidate a judge.]
(b) Protecting colleagues. Some comments imply that, in permitting cigarettes, R. Feinstein acted in order to improperly protect his smoking colleagues. I see this as highly implausible. First, because R. Feinstein made other decisions that offended his colleagues. Second, because he may be acting properly under Jewish law to protect the reputation and public standing of colleagues, i.e. communal leaders and halakhic authorities. Were consideration of colleagues improper, he would not have mentioned this reason explicitly. (Judges in every legal system need to protect the integrity of other judges. Each legal system can be evaluated in terms of how judges protect each other, and whether they are worthy of such protection.)
(c) Smokers as fools. Since R. Feinstein permits smoking because “God preserves fools”, one might infer that only fools are permitted to smoke. However, I think that the reference to “fools” (peta’im) should not be taken too literally. (Talmudic law can borrow phrases like this from the Hebrew Bible and change/ignore the original meaning.) Would R. Feinstein imply that smokers are fools, when he himself refers to gedolim as smokers. He also speaks respectfully and sympathetically of average, hard-working smokers.
(d) A ban could have saved many lives. An anonymous commenter assumes that many smokers “took [R. Feinstein's] words as gospel from above”. However, I would point out that any smokers (and community leaders) who sincerely wanted to take R. Feinstein’s words as gospel would have known to stop smoking based even his first psaq. The 1981 letter appeals to his followers and strongly opposes smoking, even if it does not consider it technically forbidden.
In my next post, I will discuss how other comments at Hirhurim sought to explain or defend R. Feinstein’s position on the smoking of cigarettes.
PS Dedicated to my mother, an early adopter of anti-smoking policies, and to my father, for following her psaq.
 Perhaps I’m too sanguine with “unintended” because, by approx the 1950s, tobacco companies intentionally took advantage of the addictive aspects of cigarettes. Still, even in knowingly selling a nicotine delivery device, the companies do not intend to kill off their customer base.
 Hirhurim cited R. Feinstein's psaq on marijuana, translated here.
 The 1963 letter (Igrot Moshe YD 249): “One should certainly take care not to start smoking, and to take proper care in desisting. But should one conclude that it is forbidden as an activity dangerous to one’s health? The answer is that because the multitude are accustomed to smoking, and the Gemara in such a case invokes the principle that “the Lord preserveth the simple,” tractates Shabbat 129b and Niddah 31a, and in particular since some of the greatest Torah scholars in the present and previous generations do or did smoke [there is no prohibition]. Consequently even someone who does take the stringent view, and does not smoke out of concern for the health danger, may properly offer a smoker a match, and not be concerned about the prohibition against facilitating a transgression.” Translated by Menachem Slae. Smoking and damage to health in the halakhah. Jerusalem, Acharai Publ., 1990
I have not seen the 1981 letter translated. (Igrot Moshe HM 2:76)
 However, R. Feinstein ruled against indoor pollution from tobacco as a nuisance, not as a toxic pollutant. (Igrot Moshe HM 2:18, letter dated 1980)
 R. Waldenberg translated in B’Or ha’Torah 8 (1993) and, with R. Halevi, by R. Helfgot here.
 "... it is certainly better not to smoke, particularly for a Ben Torah, since this is a habit which maybe dangerous and which affords no benefit or pleasure to anyone who is not addicted [hur'glu]. Certainly one should not take up smoking or allow his children to do so, even if he himself is already addicted [nitragel]. Besides the danger involved, there is good reason to prohibit smoking* [assur le-hitragel] because one should not habitualize himself to all sorts of pleasures [ta'avot] ...." Translated by Slae, op cit, p.41, transliterations mine. *Better: "prohibit getting addicted"
 Ari: "I heard from a talmid of R David Feinstein that 'shome pisuim Hashem' isn't a Heter. It means if you do this then shomer pisuim Hashem ie you're an idiot but go ahead because G-d guards fools."