Recent trends in children's exposure to second-hand smoke in England: cotinine evidence from the Health Survey for England.

Aims: To examine changes in children's exposure to second-hand tobacco smoke in England since 1998.

Design: Repeated cross-sectional surveys of the general population in England.

Setting: The Health Survey for England.

Participants: A total of 37 038 children participating in surveys from 1998 to 2012, 13 327 of whom were aged 4-15 years, had available cotinine and were confirmed non-smokers.

Measurements: The proportion of children with smoking parents; the proportion of children living in homes reported to be smoke-free; the proportion of children with undetectable concentrations of cotinine; linear and quadratic trend estimates of geometric mean cotinine across years.

Findings: By 2012, 87.3% of children lived in a home that was smoke-free {97.2% [95% confidence interval (CI) = 95.9-98.1] when parents were non-smokers, 61.3% (95% CI = 55.5-66.8) when one or both parents smoked}. A total of 68.6% (95% CI = 64.3-72.6%) of children had undetectable cotinine in 2012, up from 14.3% (95% CI = 12.7-16.0%) in 1998. There was a highly significant linear trend across years (with a small but significant quadratic term) to declining geometric mean cotinine in all children from 0.52 ng/ml (95% CI = 0.48-0.57) in 1998 to 0.11 ng/ml (95% CI = 0.10-0.12) in 2012. Children from routine/manual backgrounds were more exposed, but experienced similar gains across years to those from non-manual backgrounds.

Conclusions: In England, children's exposure to second-hand smoke has declined by 79% since 1998, with continuing progress since smoke-free legislation in 2007. An emerging social norm in England has led to the adoption of smoke-free homes not only when parents are non-smokers, but also when they smoke.