Is one cigarette a day, dosage low enough for the body to benefit from it, or atleast not be damaged by it? Is a pack of cigarettes high enough to kill you if

Is one cigarette a day, dosage low enough for the body to benefit from it, or atleast not be damaged by it? Is a pack of cigarettes high enough to kill you if you smoke it all at once ? I know quite a few friends who get through a pack a day. I didn't say 365 cigarettes at once. Everyone knows its too high a dosage that might actually kill a person, just like a high enough dose of caffeine or alcohol. I don't think a cigarette a day is low dosage. While you might not die of a heart attack or get lung cancer directly from smoking, it might still increase the risk of serious diseases given other environmental conditions, your fitness level, diet, etc. The 2 drinks a day has to be seen in a similar light.