"Quitting smoking before age 40, and preferably well before 40, gives back almost all of the decades of lost life from continued smoking," says Dr. Prabhat Jha, head of the Centre for Global Health Research at St. Michael's Hospital and a professor in the Dalla Lana School of Public Health at the University of Toronto.
"That's not to say, however, that it is safe to smoke until you are 40 and then stop," Jha adds. "Former smokers still have a greater risk of dying sooner than people who never smoked. But the risk is small compared to the huge risk for those who continue to smoke."
The findings were published January 24 in the New England Journal of Medicine. October, a study found that women can add nine years to their lives by quitting smoking before the age of 40, although they still face a 20-percent higher death rate than those who never smoked. That study, a survey of nearly 1.2 million women in Britain, was published in the journal The Lancet.