First of all, the Church doesn’t need to give an official answer to this question just because cigarettes are “popular”. Why does anyone smoke in the first place, surely it’s not for the benefit of God almighty is it…? Course not, we do it initially for selfish reasons only.
There are millions of “acts” that people can do that would be gravely sinful, and the Church has/will/can-not name them all. Have you ever watched “My Strange Addiction”…? I think that being addicted to eating comet cleanser is also a mortal sin. See for yourself.
youtube.com/watch?v=QF_YH_elBKE&feature=related
Just because cigarette smoking is “popular” doesn’t make it any less sinful.
The CCC states that “The use of drugs inflicts very grave damage on human health and life. Their use, except on strictly therapeutic grounds, is a grave offense.”… So what are “drugs” according to the Catholic Church…? Would’nt “drugs” include any foreign substance that one puts into one’s body that damages human health…? This could include comet cleanser,cigarette smoke, or cocaine.