Socioeconomic differences in second-hand smoke exposure among children in Scotland after introduction of the smoke-free legislation

Abstract

Background: To examine the impact of the Scottish smoke-free legislation on social inequalities in secondhand smoke (SHS) exposure among primary school children.

Methods: Comparison of nationally representative, cross-sectional, class-based surveys carried out in the same schools before and after legislation. Participants were 2532 primary school children (primary 7; aged around 11 y) surveyed in January 2006 (before legislation) and 2389 in January 2007 (after legislation). Outcome measures were salivary cotinine concentrations, self-reported family socioeconomic classification (family SEC) and family affluence scale (FAS).

Results: After adjusting for number of smoking parents, mean cotinine concentration varied significantly across both family SEC and FAS groups, and increased significantly stepwise from high to low family SEC/FAS. Mean cotinine fell in all family SEC/FAS groups after legislation. The relative drop in mean cotinine was equal across all family SEC/FAS groups. Adding an interaction term between survey-year and family SEC/FAS to the model showed an increase in inequalities over time, but was only significant at the 93% level using FAS and 73% using family SEC.

Conclusion: Inequalities in SHS exposure exist among 11-year-old children in Scotland. Smoke-free legislation has reduced exposure to SHS among all children. Although the greatest absolute reduction in cotinine is observed in the lowest SEC/FAS group, cotinine levels remain highest for this group and there is a suggestion of possible increases in inequalities, which may warrant longer-term monitoring.