Editor,—Smoke free workplaces have been found to reduce cigarette consumption among smokers1-4 and smoking prevalence.1 4 5 In countries with a high smoking prevalence such as Japan (men, 55%),6 a total ban is unusual but policies such as limiting smoking to designated smoking areas are common.7 However, the impact of such restrictions on smoking has been weak.4 8 9 Furthermore, evidence linking restrictive policies to smoker motivation to quit is limited.4 5 The present study therefore examined the relation between common workplace restrictions on smoking, and smoking behaviour and attitudes toward quitting in Japan.

A health survey using self administered questionnaires was conducted among a random sample of employees of a municipal office in Japan.10 A response rate of 89% was obtained. The present study analysed data from 1040 male indoor workers subject to one of three policies: a workroom ban; a work area ban with a smoking areainside the workroom; and time limits on smoking and prohibition of smoking during meetings (minimum restriction). Smoking behavioural characteristics and desire to change smoking were compared among these policies, with adjustment for age.

A 12% lower prevalence of smoking and a 17% higher proportion of ex-smokers were found in workplaces with a workroom ban than in those with minimum restrictions (table 1). Among current smokers, the workroom ban was significantly associated with a lower consumption of cigarettes (mean difference from minimum restrictions, 4.1 cigarettes a day; p < 0.001). The proportion of heavy smokers who consumed 25 cigarettes or more per day was 32% lower among smokers subject to a workroom ban compared to those working under minimum restrictions. Smokers subject to a workroom ban were more likely to have attempted to quit, and less likely to become irritated when they could not smoke for 30 minutes. In contrast, no such differences were observed for smokers subject to a work area ban. The proportion of smokers with a desire to quit did not differ according to the type of smoking restriction. Contrary to expectation, a lower proportion of smokers subject to a workroom ban wanted to reduce cigarette consumption and a higher proportion intended to maintain their current smoking status, compared with individuals subject to minimum restrictions.

The present finding of reduced cigarette consumption among smokers subject to a workroom ban is consistent with the results of studies of comprehensive restrictions allowing smoking only in limited areas.3 4 8 9 A low prevalence of heavy smoking associated with a workroom ban is also consistent with a previous report.2 Furthermore, a workroom ban was associated with less likelihood of becoming irritated when unable to smoke. These findings support the hypothesis that a workroom ban reduces cigarette consumption and levels of addiction to smoking, and thus helps smokers to quit. In contrast, our study suggests that a work area ban with designated smoking areas inside the workroom, another common policy in Japanese offices,7 has little influence on smoking behaviour. Such an incomplete work area ban may not constitute a physical and psychological barrier against smoking.

Some studies have indicated that smoking restrictions increase motivation to quit.4 5 Our study, however, indicated that desire to quit among continuing smokers did not increase as smoking restrictions became tighter; conversely, a workroom ban was associated with somewhat low motivation to change smoking status. Further study is required to confirm whether smoking restrictions enhance motivation to quit.

From a public health perspective, the favourable effects of workroom bans on smoker behaviour should be stressed because, if many businesses in Japan adopt such a stringent smoking policy, smoking intensity or prevalence in men in Japan, currently the highest among developed countries,6 will be reduced at an accelerated rate.