Smoke-free homes in England: Prevalence, trends and validation by cotinine in children

Objective: To examine the prevalence of smoke-free homes in England between 1996 and 2007 and their impact on children’s exposure to secondhand smoke.

Design: A series of annual cross-sectional surveys: the Health Survey for England.

Setting and participants: Nationally representative samples of non-smoking children aged 4-15 (N=13,365) and their parents interviewed in the home.

Main outcome measures: Cotinine measured in saliva. Smoke-free homes defined by ‘no’ response to “Does anyone smoke inside this house/flat on most days?” Self-reported smoking status of parents and self-reported and cotinine validated smoking status in children.

Results: The proportion of homes where one parent was a smoker that were smoke-free increased from 21% in 1996 to 37% in 2007, and where both parents were smokers from 6% to 21%. The overwhelming majority of homes with non-smoking parents were smoke-free (95% in 1996; 99% in 2007). For children with non-smoking parents and living in a smoke-free home the geometric mean cotinine across all years was 0.22ng/ml, For children with one smoking parent geometric mean cotinines were 0.37 ng/ml when the home was smoke-free and 1.67ng/ml when there was smoking in the home; and for those with two smoking parents, 0.71ng/ml and 2.46ng/ml. There were strong trends across years for declines in cotinine concentrations in children in smoke-free homes for both children of smokers and non-smokers.

Conclusion: There has been a marked secular trend towards smoke-free homes, even when parents themselves are smokers. Living in a smoke-free home offers children a considerable, but not complete, degree of protection against exposure to parental smoking.