Yes, you know, smoking is killing you, blah, blah, blah. But is there any point in quitting? Absolutely, say researchers from Duke University, who counted the years of healthy life enjoyed by smokers, former smokers, and people who'd never smoked.

What the researchers wanted to know: What is the effect of smoking on health late in life?

What they did: The researchers used data from two studies. One, the Health and Retirement Study, was carried out between 1992 and 2000. People who were born between 1931 and 1941 answered questions every two years about their health, disability, and other topics. The participants answered questions about smoking, too; more than a quarter were smokers. The other survey, the Asset and Health Dynamics About the Oldest Old, started in 1993 and asked people 70 years or older about their health. Only 11 percent of those respondents were smokers, while about 45 percent used to smoke. The researchers looked at years of healthy life, not how long the participants lived; if they weren't healthy later, those years didn't count.

What they found: Fifteen years after quitting, the number of healthy years remaining to former smokers are the same as people who never smoked.

What it means to you: Quitting smoking is good for you.

Caveats: The authors didn't prove that quitting smoking caused the better lives of ex-smokers; they just proved that the two are linked. Quitting smoking and living well could both be related to some other risk factor.

Find out more: The "Bob Quits" antismoking campaign http://www.bobquits.com

Read the article: Ostbye, T. and D.H. Taylor. "The Effect of Smoking on Years of Healthy Life (YHL) Lost Among Middle-Aged and Older Americans." Health Services Research. June 2004, Vol. 39, No. 3, pp. 531–552.

Abstract online: http://www.ncbi.nlm.nih.gov/