Objective: To follow the development of a class of pupils' tobacco habits for seven years, and to study differences in tobacco use between girls and boys.
Setting: Kronoberg County in southern Sweden.
Subjects: All the approximately 2000 pupils were followed from approximately age 12 to approximately age 18.
Design: Yearly cross-sectional surveys from 1994 to 2000. Each year, the pupils filled in an established tobacco questionnaire. They did it anonymously in the classroom.
Main outcome measures: Percentage of smokers, number of cigarettes smoked per day, and percentage of pupils using "snus", the Swedish variety of oral moist snuff.
Results: From grade 6 of compulsory school to grade 12 of upper secondary school, the proportion of daily smokers rose, from 0.2% to 22% for girls and from 0.5% to 14% for boys. Among both genders, the increase occurred mainly between grades 7 and 10, and from grade 10 onwards the daily smokers were the largest group of smokers. Starting from grade 9, boys had higher total tobacco consumption than girls, as a result of their increased use of "snus", and at the end of the study 39% of the boys used tobacco compared with 34% of the girls.
Conclusion: Studying young people's tobacco habits over time gives an understanding of when preventive measures should be implemented. In order for these to influence attitudes, they should be put in place well before tobacco is introduced.