Some smokers try to justify their habit by cutting back. But the risks of even less than a pack a day are high, according to researchers with the National Cancer Institute.

To get a better picture of the health effects of light smoking, researchers tracked more than 290,000 adults aged 59 to 82, including more than 22,000 current smokers and more than 156,000 former smokers, who completed surveys in 2004 and 2005.

By 2011, compared to people who never smoked, adults who consistently smoked at least part of one cigarette a day were 64 percent more likely to have died of any cause, researchers report in JAMA Internal Medicine.

Smoking one to 10 cigarettes a day was associated with 87 percent higher odds of dying from all causes during the study than not smoking at all.

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