England's legislation on smoking in indoor public places and work-places: impact on the most exposed children (2012)

Aims: To examine whether English legislation to make virtually all indoor public places and work-places smoke-free on 1 July 2007 displaced smoking into the home and hence increased the proportion of children exposed to levels of second-hand smoke known to be detrimental to health.
Design: Repeated cross-sectional study with data from 10 annual surveys undertaken from 1996 to 2008.
Setting: England.
Participants: Nationally representative samples of non-smoking children aged 4-15 years old living in private households.
Measurements: Salivary cotinine, parental smoking status, whether smoking is allowed within the house, socio-demographic variables.
Findings: The proportion of children exposed to damaging levels of second-hand smoke (defined as those with cotinine levels >1.7 ng/ml) has fallen over time, from 23.5% in 1996 to 12.6% in 2008. The legislation was not associated with further changes in the proportion of children above this threshold - the odds of having cotinine >1.7 ng/ml did not change after adjustment for the pre-legislative trend and confounders (odds ratio: 1.0, 95% confidence interval: 0.78, 1.4). Non-significant associations were also found when examining children by parental or household smoking status.
Conclusions: Legislation to prohibit smoking in indoor public places and work-places does not increase the proportion of children exposed to damaging levels of second-hand smoke. Even in a country with a strong tobacco control climate, a significant proportion of children remain highly exposed to second-hand smoke and future policies need to include interventions to reduce exposure among these children.