When and why children first start to smoke.

Most investigations of smoking in children focus on prevalence in which uptake and maintenance are confounded. This paper reports an analysis of pure incidence data in a cohort of over 6000 Derbyshire schoolchildren followed for ten years investigated using survival data analysis techniques. Over 70% of the cohort tried at least one cigarette before the end of the fifth year of secondary school. Some 40% identified themselves as regular smokers while at school. The risks of taking up regular smoking were higher if, at the age of 11.7-12.7 years, the children had smoking siblings, opposite sex friends, were dismissive of the health hazards and susceptible to peer pressure. More girls than boys in that age range spent time with opposite sex companions and in organized social activities which in turn were significantly associated with the risk of taking up smoking. Thus the earlier physical and emotional development of girls may help explain recent findings that adolescent girls are now more likely to smoke than boys of the same age. The greatest incidence of regular smoking occurred when the average age was increasing from 14.2 to 15.2 years. This has very clear implications for the timing of anti-smoking interventions.