Most smokers begin smoking in adolescence, It is less well known how young
people quit smoking and the factors that are associated with this process.
A 15-year follow-up study on the North Karelia Youth Project has made it po
ssible to assess these factors using a longitudinal study design. The proje
ct began in 1978 with students in Grade 7 of junior high school (age 13 yea
rs) and concluded in 1980 when the students reached Grade 9 (age 15 years),
The follow-up study included four additional surveys. The present analyses
are based on the data collected at ages 15, 21 and 28. The original sample
comprised 903 students and the response rate of the last survey was 71%, A
quarter (26%) of daily smokers and about half (46%) of occasional smokers
at age of 15 had quit by the age of 28, The cessation rate was higher among
females than males (P = 0.006), The cessation rate was higher among marrie
d (P = 0.015), employed (P = 0.01) and white-collar workers (P = 0.006), Ce
ssation was less prevalent among those who had friends (P < 0.001) and fami
ly (P = 0.012) members who smoked. The cessation rate was lower among those
who consumed fatty milk (P = 0.050), had less leisure-time physical activi
ty (P = 0.032) and consumed more alcohol (P < 0.001), One-third of all teen
age smokers stop smoking before the age of 28, averaging a 2.3% annual decl
ine. Cessation is greater among occasional than daily smokers and greater o
verall among females.