Persistence of socioeconomic differences in adolescents' environmental tobacco smoke exposure in Finland: 1991-2009.

Aims: Socioeconomic differences in children's exposure to environmental tobacco smoke (ETS) in favour of those with higher positions are known, but research is scarce on whether differences have persisted when smoking restrictions have been tightened. We examined socioeconomic differences in adolescents' ETS exposure from 1991 to 2009 in Finland where the tobacco law has gradually restricted smoking of population.

Methods: National cross-sectional surveys (1991-2009) in 12-18-year-olds (N=72,726, response rate 77-56%). An outcome measure was self-reported exposure to ETS (≥ 1 hour/day). Parents' socioeconomic and adolescent's individual social position (school performance/career) were used as independent variables. Across four time periods, associations were studied by logistic regression.

Results: Over the study period 1991-2009, the proportion of adolescents exposed to ETS decreased from 17% to 6% (p ≤ 0.001). There were large and persistent differences between socioeconomic and parents' smoking groups. The decrease occurred in all groups but was smaller among 16-18-year-olds whose father had a low education. A steeper decline occurred among 16-18-year-olds who were not in school or were in vocational school with poor school performance compared with those with more advanced educational career. Compared with other subgroups, the decline in ETS exposure was greater among those whose parents were smokers.

Conclusions: Adolescents' ETS exposure remarkably decreased over time, when tobacco control measures were tightened, particularly among children of smoking parents. Socioeconomic differences persisted although diminishing differences were observed between educational groups at age 16-18.