Changes in exposure of adult non-smokers to secondhand smoke after implementation of smoke-free legislation in Scotland: national cross sectional survey

Haw, Sally J principal public health adviser
Gruer, Laurence director of public health science

¹ NHS Health Scotland, Edinburgh EH12 5EZ
² NHS Health Scotland, Glasgow G3 7LS

Related to: doi: 10.1136/ bmj.39311.550197.AE

Correspondence to: S Haw [email protected]

doi:10.1136/bmj.39315.670208.47

We thank Ruth Gosling, Sally Malam, and staff at BMRB Social Research, who conducted the health education population survey and prepared the database; Sonnda Catto of NHS Health Scotland who managed the commissioning of the health education population survey; and Colin Fereyabend, Mira Doig, and staff at ABS Laboratory, who advised on and performed the cotinine assays. We also thank Patricia Akhtar and Dorothy Currie of Child and Adolescent Health Research Unit, University of Edinburgh, and Rob Elton, independent consultant, for support with the analysis and presentation of results.

Contributors: SH contributed to the design of the study, undertook data analysis, and wrote the paper. LG contributed to the design of the study and the writing of the paper. SH is guarantor.

Funding: NHS Health Scotland and the Scottish Executive.

Competing interests: None declared.

Provenance and peer review: Not commissioned; externally peer reviewed.

Accepted: 22 August 2007

BMJ 335(7619):p 549-556, September 15, 2007.

Objective

To measure change in adult non-smokers’ exposure to secondhand smoke in public and private places after smoke-free legislation was implemented in Scotland.

Design

Repeat cross sectional survey.

Setting

Scotland.

Participants

Scottish adults, aged 18 to 74 years, recruited and interviewed in their homes.

Intervention

Comprehensive smoke-free legislation that prohibits smoking in virtually all enclosed public places and workplaces, including bars, restaurants, and cafes.

Outcome measures

Salivary cotinine, self reported exposure to smoke in public and private places, and self reported smoking restriction in homes and in cars.

Results

Overall, geometric mean cotinine concentrations in adult non-smokers fell by 39% (95% confidence interval 29% to 47%), from 0.43 ng/ml at baseline to 0.26 ng/ml after legislation (P<0.001). In non-smokers from non-smoking households, geometric mean cotinine concentrations fell by 49% (40% to 56%), from 0.35 ng/ ml to 0.18 ng/ml (P<0.001). The 16% fall in cotinine concentrations in non-smokers from smoking households was not statistically significant. Reduction in exposure to secondhand smoke was associated with a reduction after legislation in reported exposure to secondhand smoke in public places (pubs, other workplaces, and public transport) but not in homes and cars. We found no evidence of displacement of smoking from public places into the home.

Conclusions

Implementation of Scotland’s smoke-free legislation has been accompanied within one year by a large reduction in exposure to secondhand smoke, which has been greatest in non-smokers living in non-smoking households. Non-smokers living in smoking households continue to have high levels of exposure to secondhand smoke.