I like this idea a lot. I have found cigarettes in the boys' bathroom of my middle school repeatedly, and co-teachers seem alarmingly blase about it.
I have been considering bringing it up in class for a while now. But I'm having trouble thinking of a way to make it student-centered, rather than just me lecturing them about the evils of smoking. Were you able to use this to stimulate discussion or make the students somehow use/produce the language? Did you add any activities or a game at the end?
On the lesson's "anti-american" statistical page - American tobacco companies are exceptionally guilty here anyway, so it's not exactly Ahmadinejad-style rabidly anti-American lies we're talking about here....and, sound statistical methods aside, I know my students. They aren't into statistics, but they're really into what's cool. Every pack of cigs I've found in the school are Marlboro. Suggesting the idea, however simplistic, that their little Korean bodies are being tainted by dirty American cigarettes might go a lot farther with them than pictures of black lung disease. If I can indulge the fantasy of the first thanksgiving and teach them about pilgrim-indian harvest feasts without going into the complexities of America's colonial genocide, I can indulge the idea that smoking isn't really "Korean" too.
On the "don't judge Koreans you rude foreigner" claims - smoking kills. That's just...true. Honestly, if I thought something as morally insignificant as my passport were reason enough to keep me from caring about my students' health, I wouldn't be a teacher. (Yes, even in Korea.)