Effect of restrictions on smoking at home, at school, and in public places on teenage smoking: cross sectional study

British Medical Journal, August 5, 2000 by Melanie A Wakefield, Frank J Chaloupka, Nancy J Kaufman, C Tracy Orleans, Dianne C Barker, Erin E Ruel

For each of the analyses, we found no significant interactions between parental smoking and home bans, or between bans in different environments, on the smoking outcome variables.

Discussion

Our study of the relation between smoking restrictions in a range of environments and smoking behaviour of teenagers suggests that restrictions in the home and public places and enforced bans in schools have a protective effect on teenage smoking. These findings are subject to at least four limitations. Firstly, our data are from a cross sectional survey, which limits attributions about the direction of causality between variables. There may be other factors that influence teenage smoking apart from restrictions on smoking, and these could lead to an artificial relation between restrictions and youth smoking. For example, in places where stronger restrictions exist on smoking in public places, the environment for tobacco control may be more favourable and there may be other policy influences that promote lower smoking rates by teenagers. We have not controlled for such factors. However, we did control for adult smoking, which is also likely to be influenced by these policies, and found little change in the model variables and no interactions with adult smoking. Nevertheless, our findings require further examination in longitudinal studies.

Secondly, we used a previously untested three point measure for extensiveness of public places laws. Preliminary analyses with a five point scale developed in the 1980s[8 19] produced a similar pattern of findings, although we were concerned about using the older scale because it produced a ceiling effect, with most cases lying in the strongest possible level. Our three point measure better captured the progress that has been made over the past decade in implementing restrictions on smoking in public places.

Thirdly, we had no information about the duration of the restrictions in any of the environments we examined, and it may be that effects change over time as teenagers accommodate to a more restrictive environment. Finally, we did not have measures of actual enforcement of, or compliance with, laws restricting smoking in public places. However, studies of restrictions on smoking at work and in other public places such as restaurants suggest that they have high levels of compliance.[20-23]

Notwithstanding these cautions, our finding that home smoking bans reduce smoking uptake and prevalence is consistent with other research. Studies in Europe and the United States have shown that parental opposition to smoking and setting clear standards about smoking are more important predictors of teenagers' intentions to smoke than is parental smoking behaviour.[24-26] Our results apply both where parents do and do not smoke, suggesting that even if parents are unable to quit smoking to set a good example for their children, banning smoking in the home may reduce the likelihood of teenagers taking up smoking. By comparison, stronger restrictions in public places are likely to have a more modest effect.