Smoking two packs of cigarettes a day for twenty years reduces one's lifespan by

Smoking two packs of cigarettes a day for twenty years reduces one's life span by EIGHT YEARS.
Cigarette smoking has serious consequences on the health of the smokers and it has been reported that for every cigarette a man smokes his life span is reduced by 11 minutes, thus, a cartoon of cigarette a day is equivalent to a day and a half [36 hours] loss in life span.