The impact of implementation of smoke-free legislation in England on cotinine levels in adults
- 1National Centre for Social Research (NatCen), London, UK
- 2Department of Epidemiology & Public Health, University College London, London, UK
Objective
To investigate the impact of the implementation on 1st July 2007 of smokefree legislation in England on tobacco smoke exposure and cotinine levels in non-smoking adults.
Participants
Nationally-representative sample of 5330 (2585 male) self-reported non-smokers (never or ex-smokers) aged 16+ interviewed in the 2007 Health Survey for England; 3183 cotinine-validated non-smokers aged 16+ (1441 men) with a saliva sample.
Main Outcome Measures
Mean weekly duration of self-reported tobacco smoke exposure; geometric mean salivary cotinine. Cotinine is an excellent marker of exposure to tobacco. Low levels indicate exposure to other people’s smoke; 12 ng/ml is the best cut-off for personal tobacco use. Analyses adjusted for the complex (stratified, clustered) sampling design and weighted for non-response to interview and saliva sample, as appropriate.
Results
Most adult non-smokers reported no-one smoked in the home most days (93% before and 95% after 1st July 2007). Non-smokers’ mean self-reported exposure to tobacco smoke fell from 4.2 hrs (95% CI 3.6 to 4.9) before to 2.0 hrs (1.5 to 2.4) after 1st July in men and from 3.5 hrs (2.9 to 4.1) to 1.4 hrs (1.0 to 1.7) in women (both p<0.001). Exposure was inversely related to age-group but fell most in those with the highest exposure: from 5.9 hrs (4.9 to 6.9) to 2.8 hrs (2.3 to 3.3, p<0.001) aged 16–34 yrs; from 3.4 hrs (2.9 to 4.0) to 1.4 hrs (1.0 to 1.7, p<0.001) aged 35–64 yrs; and 2.1 hrs (1.5 to 2.7) to 0.9 hrs (0.4 to 1.4, p = 0.002) aged 65+. Similar falls occurred in all three NS-SEC groups: professional/managerial from 4.2 hrs (3.5 to 5.0) to 1.7 hrs (1.3 to 2.1); intermediate from 3.9 hrs (2.9 to 4.8) to 1.7 hrs (1.4 to 2.1); and routine/manual from 7.9 hrs (6.7 to 9.1) to 4.9 hrs (4.0 to 5.8) (all p<0.001). Overall, the proportion with undetectable salivary cotinine levels rose from 32% to 46% of cotinine-validated non-smokers. Geometric mean cotinine levels in cotinine-validated non-smoking adults fell from 0.20 ng/ml (95% CI 0.18 to 0.22) in the first half of 2007 to 0.14 ng/ml (0.13 to 0.15) after 1st July 2007 in men and from 0.19 ng/ml (0.17 to 0.21) to 0.12 ng/ml (0.11 to 0.13) respectively in women (both p<0.001). As with self-reported exposure, levels before July 2007 were highest in the youngest age-group, who experienced the largest falls: from 0.23 ng/ml to 0.15 ng/ml aged 16–34, p<0.001; 0.17 ng/ml to 0.11 ng/ml aged 35–64, p<0.001; and 0.17 ng/ml to 0.14 ng/ml aged 65+, p = 0.001. Similar, significant falls occurred in all three NS-SEC groups.
Conclusion
The legislation has been successful in its primary aim, to reduce the exposure of non-smokers to tobacco smoke pollution. It has decreased absolute inequalities.
