Pre- and post-implementation responses on the five-point scale were tabulated, sub-divided by age group (up to 30 years and over 30 years) and by smoking status. Since occasional and ex-smokers are likely to be heterogeneous groups, and since their numbers were small, results by smoking status are presented only for smokers and non-smokers. (In general, attitudes for the omitted groups lay between those of smokers and non-smokers).

Change on the five-point scale between the responses given before and after the legislation was calculated for each question and for each respondent. Change in opinions after the legislation were summarised by averaging these numbers to produce a 'mean shift' parameter; in each case, the sign was arranged to be positive for a change in attitude more favourable to anti-smoking legislation. The statistical significance of these shifts, and of comparisons between the distributions of changes by age, gender and by smoking, was assessed using the Wilcoxon-Mann-Whitney U-test, 22 a non-parametric test for the difference in the median of two distributions.

Of the 371 bar workers who participated in the baseline survey, 266 (72%) were seen at both baseline and follow-up. Table 1 compares subjects followed up with those lost to follow up. The two groups did not differ significantly in gender, smoking status, level of education or attitudes at baseline. However, there were differences in follow-up rate by age and location. The proportion of those aged over 30 who were successfully followed up was 81% for all three locations. The follow-up rate among those aged 30 or younger was 74% for Aberdeen/shire and Glasgow but only 59% for Edinburgh/Borders, reflecting Edinburgh's younger and more transient bar worker population. The broad similarities in demographics between those followed up and those lost to follow up suggest that the continuing participants may be considered as broadly representative.

Table 4 shows the attitudes towards each question, pre- and post-implementation, split by age group up to and above 30 years. Not all respondents answered every question. For questions A, C, D, E, there was a significant positive (i.e. pro-legislation) shift in attitudes in both age groups. For questions B, F, G, I, a significant shift was seen only in the older group. There was no significant shift for question H, but both groups had anyway been initially supportive of the need to protect workers' health, so there was less opportunity here for increased support. Whether or not significant, the shifts for all of these eight questions were in the positive direction, except for question G, asking whether the smoking legislation will encourage (has encouraged) smokers to quit smoking. Here the shift was negative, although significant only for those 30 and under [see Additional file 1].

Before the legislation was introduced the non-smokers were generally more positive towards it than the smokers (Table 5). Patterns of change were very similar to those in Tables 2, 3 and 4. Questions A, C, D, E, F all showed significant or almost significant shifts in both smokers and non-smokers, while for questions B and I the shift was seen much more in the smokers, who had been initially less positive. Again, the only sizeable negative shift was on question G [see Additional file 1].

Overall, bar workers were generally quite positive towards the smoking restrictions pre-implementation and, regardless of age and smoking status, they became even more positive at follow-up. Age and smoking status affected attitude pre-implementation, with the young and the non-smokers being more positive. The changes in attitude were seen in all smoking groups; there were differences by age group, with the initially more sceptical older group becoming rather less so after the implementation.

The detrimental effects of smoking have been known for decades 23, and according to the Scottish Health Education Population Survey the general population are aware of the health risks associated with smoking, but may view smoking as a personal choice. Therefore the main thrust of current health education efforts is on raising awareness of the health risks of smoking to others and reducing the acceptability of second-hand smoke exposure 24. To this end Scotland has followed the public health policies in many developed countries, in prohibiting smoking in enclosed public places in March 2006. Early indications are that smoke-free legislation in Scotland has greatly improved the air quality in bars, providing greater protection to bar workers and patrons from the harmful effects of second-hand smoke 25. This study shows that bar staff were positive about the likely effects of the legislation before it was implemented, and became even more so afterwards.

The high level of agreement that smoke-free legislation was needed to protect bar workers' health may be due to the comprehensive information campaign (NHS Health Scotland, The Scottish Executive & Cancer Research UK) in the months leading up to the legislation. The generally positive experience of the legislation in Ireland may also have influenced Scottish bar workers' expectations and attitudes towards smoking restrictions 26.

One of the criticisms of the legislation has been the possibility that smoking would be displaced to the home. This concern was raised by the then Secretary of State for Health for England and Wales in September 2004 and is also reflected in the initial responses from the bar workers 27. Their concern decreased by the time of the post-implementation interviews, when only 26% believed that displacement had occurred. However, an evaluation of the behavioural impact of the Irish smoke-free legislation found that the proportion of Irish homes with smoking bans increased 16.

Bar workers in this study expressed concern that the legislation might lead to economic losses for the pub trade, perhaps reflecting concerns expressed by the hospitality industry 28 rather than the experience of other countries, which have not seen trade affected adversely 293031. We note that there was a more positive attitude to business and job security at the follow-up survey.

The only topic where we observed a negative shift in attitudes towards the legislation was in relation to whether the legislation would encourage smokers to quit. This may reflect some bar workers' observations that they, their colleagues and patrons have continued to smoke. However, studies that have assessed changes in smoking habits since the introduction of smoke-free legislation report that the measures helped smokers quit 16.

While both smokers and non-smokers appeared to support the legislation, initially the attitudes of older bar workers were less positive than those of younger bar workers. The older workers generally demonstrated a greater change, perhaps reflecting a marked shift in social norms about the acceptability of smoking.

Those lost to follow-up were on average younger by three years. This reflects the fact that younger bar workers are more mobile and likely to have shorter periods of employment within the hospitality sector. The possibility for response bias was thus greater among the younger group, but it is clear from comparison of Tables 2 and 3 that the distribution of initial attitudes among those followed up was almost identical to that of the initial sample. We have no reason to believe that the reasons for loss to follow-up are linked with attitudes to smoking, or that the sample followed up are not representative of young bar workers generally. There was less non-response among the older group, representative of those with longer service and experience who are likely to benefit most from the legislation because of their reduced exposure to SHS over time, and who have the greatest role to play in its enforcement. Figures from Local Authorities (municipalities) show that, in the first few months following the Scottish legislation, a compliance rate in excess of 99 per cent was achieved 32. The high compliance rates are testament to bar workers' positive attitudes towards the legislation as they performed the role of 'gate-keepers' in enforcing the legislation within their premises.

The refusals rate of 55% of the bar managers approached at baseline is similar to that observed in other studies in this setting, 533 perhaps reflecting a protest against the impending ban. In recognition of the low take up rate at baseline our sampling strategy aimed to include a diverse sample of bars covering a broad range of socio-economic areas in urban, semi-urban and rural settings to provide an overall picture of the experience of legislation.

Further work to examine the attitudes of this group of bar workers is planned as part of the one-year follow-up of the BHETSE study. Some of our group are also involved in a similar study of bar workers as part of the evaluation of smoke-free legislation in England and it will be of interest to compare and contrast these two groups. Changes in respiratory health among the BHETSE cohort, and how these influence individual attitudes, may also be worth examining.

This is the first evaluation of changes in bar workers' attitudes towards legislation prohibiting smoking in enclosed public places in Scotland. This study shows that bar staff were positive about the likely effects of the legislation before it was implemented, and became even more so afterwards. This positive change in attitudes may reflect a marked shift in social norms about the acceptability of smoking.

The high level of support for smoke-free legislation in Scotland is evidence of a continuing gradual shift in public attitudes towards the harmful effects of SHS exposure, and increasing acceptance that smoke-free environments are necessary to protect bar workers' and non-smokers' health. Changing social norms relate to community-wide behaviour, as distinct from the more direct influence of family and friends, and it seems possible that the high level of support for the smoke-free legislation may have arisen from a combination of positive media reporting and an intensive educational campaign from NHS Health Scotland, CRUK and the Scottish Executive in the months leading up to the legislation. This study demonstrates that smoke-free legislation is welcomed by staff as a public health measure, with young bar workers the most positive. The evaluation of future smoke-free legislation in other countries should seek to understand the concerns and attitudes of those stakeholders involved in implementation and enforcement. In Scotland bar workers played a central role in ensuring a high level of compliance and helped establish smoke-free entertainment venues as the new social norm.