This study considers the effects of social networks on people's smoking habits. The researchers found that the smoking behavior of networks consisting of family, friends and work colleagues is relevant to the likelihood of smoking cessation for the individual.

Despite the decline in the prevalence of smoking, the habit remains the leading cause of preventable deaths in the United States with 440,000 people dying annually. This study considers the effects of social networks on smoking cessation by evaluating a group of 12,067 people from the Framingham Heart Study, who underwent repeated assessments of their smoking behavior between 1971 to 2003.

Key Findings:

• In 1971, there were many more smokers as compared to 2000, and they tended to occupy the center of their social networks as much as nonsmokers.
• By 2000, those who smoked were more likely to be at the periphery of their social networks.
• Smoking cessation by a spouse decreases one's chances of smoking by 67 percent–significantly higher than by a sibling (25%) or by a friend (36%).
• Educated individuals are more influential and more likely to be influenced than noneducated individuals in social networks.

The findings suggest that groups of smokers become nonsmokers together, which causes the average cluster size to remain high, even as the incidence of smoking decreases. The results of this study have implications for clinical and public health interventions to prevent or reduce smoking.