May I point out the evasiveness of the OP and nearly all of the comments. The true issue worth discussing (well maybe not – it has been chewed out in the CR many times) is whether there is any heter whatsoever to smoke a cigarette. I shudder to think that there are some who are willing to consider it okay to become an addict to nicotine. That issue is addressed very succinctly in several sifrei mussar, notably in the Michtav Me’Eliyahu from Rav Dessler.
I suspect that the issue being raised here is about the single cigarette, and the defensive angle on this is that the dreaded illnesses that result are not seen in the casual smoker, but only after long term smoking. Here again, I must “go off” on the very thought of it. The more contemporary seforim about smoking, quoting many, many mainstream and renowned poskim (with haskamos from many others) addresses the “single cigarette” issue, and proclaims it completely assur. If the regular smoker is committing murder (actually suicide), the small steps that contribute to the tragic end are individually assur. While opinionated, this is not really dependent on my personal feelings. The halacha is addressed quite clearly, and the same poskim we quote or consult have weighed in on the subject quite eloquently.
I am terribly bothered by the smoking that occurs on Purim, where young children are often encouraged to smoke. We would never allow our children to eat something from a hechsher we feel is inadequate. Kal vachomer something with NO hechsher, and even an issur proclaimed by nearly all recognized and reliable poskim should be banned 100%. Yes, it is as bad as the worst on the internet.
As long as we have trespassed into the territory of bad things that we ignore on Purim, in the name of simcha, the use of caps, smoke bombs, and other “Purim shtick” is a huge problem. They are used in shuls, extremely disturbing in many ways, and encroach into danger zones of playing with fire. Anyone with these shtick should be forbidden to enter a shul. If I had a shul, I would evict the parents whose children bring such contraband into the premises.
I do not think there is an age when anyone should consider something clearly assur to be okay.