The number of smokers who have quit over the last three decades has multiplied as a result of public-health campaigns, but now researchers in the U.S. say people quit smoking as groups and not as individuals.
The scientists from Harvard Medical School and the University of California, San Diego reached this conclusion following the results of a very large study conducted over thirty years.
The study involving 12,067 people revealed that people quit smoking in network clusters and quitting is not the isolated decision it might first appear to be to the individual.
Study author Professor Nicholas Christakis, says there is an almost cultural shift, where a group of people who are connected but who might not know each other, all quit together.
Professor Christakis and colleagues analyzed data from the Framingham Heart Study, an ongoing cardiovascular study begun in 1948, and recreated the social patterns contained within the study data, in order to see how health was linked to an individual's social network.
By focusing on 5,124 individuals, they found a total of 53,228 social, familial and professional ties.
At regular intervals from 1971, participants recorded births, marriages, divorces and deaths, as well as listing contact information for their closest friends, co-workers, and neighbours.
The initial and most striking discovery was that people quit smoking as groups and not as individuals.
Christakis says a small network containing three individual smokers, are affected when one quits as the 'quitter' spikes up the chance of others quitting, even indirectly.