[Family influences on future smoking habits among junior high school students in Japan]

To examine the effects of health-related behavior and family smoking habits on the future smoking habits of junior high school students in two Japanese cities with different life expectancies.

A cross-sectional study was conducted in January 2005 of all second-grade students in a junior high school in city A located in Aomori prefecture (399 students) and city B located in Nagano prefecture (447 students). Life expectancies in city B were 4.2 years longer in men and 2.9 years longer in women than in city A. Data on feelings about future smoking habits, dislike of tobacco smoke, family smoking habits and health-related behavior were collected.

The proportion of boys who went on to become smokers was higher in city A (18.7%) than in city B (10.3%). The proportions of smoking mothers and other smoking family members were also higher in city A, while the proportion of students who disliked tobacco smoke was lower. For girls in both cities, there was a significant positive association between future smoking and maternal smoking.

The findings suggest that maternal smoking habits are especially strongly correlated with future smoking in girls. The family smoking environment and health-related behavior should therefore be considered in measures to prevent smoking by students.