Int. J. Environ. Res. Public Health 2011, 8 1529 indicates over-reporting of existing voluntary smoking prohibition or restriction by subjects in this study. Together, the field observations reported previously and the results from the present study may provide the upper and lower bounds for existing voluntary smoking policies in restaurants and bars included in this study. Results of this study showed that exposure to SHS was very common even in restaurants and bars prohibiting smoking. One reason might be the misclassification of smoking policies introduced by potential over-reporting of smoking prohibition in restaurants and bars, as discussed above. Alternatively, this finding might be a result of poor compliance to voluntary smoking prohibition. According to the China Labor Statistical Yearbook 2006 [19], only 19% of the working population in Beijing had higher than high school education, which is lower than the education attainments of restaurant/bar owners or managers in this study. This may be a reason why subjects of this study had relatively higher awareness of the negative health effects caused by smoking or SHS than that reported in previous studies mentioned in the introduction part. Alternatively, the subjects might have over reported their education attainments. Subjects’ knowledge of specific hazards of tobacco smoke was much more limited, for example, only half of the subjects knew that passive smoking can cause heart disease. Similar results were found in patrons recruited from the same venues [20]. This implies that health education related to tobacco smoke and warning labels on tobacco products in China should focus on specific health hazards rather than general, vague information. Up until October 2008, the health warning on cigarette packs in China had always been “smoking is harmful to your health”, and since October, 2008, a new health warning that “Quitting smoking reduces health risk” or “Quitting smoking early is good for your health” is required to be printed on all the packs. A study showed that they were least effective in informing public of dangers of smoking, comparing to warning labels adopted by some other countries with more specific smoking hazards [21]. To educate the public with more specific health hazard of SHS is also very important to facilitate smoking bans in restaurants and bars, as shown by the regression analysis that those who knew more about SHS hazards were more likely to support governmental smoking bans in these venues and more willing to restrict or ban smoking in their own venues. Though there were some knowledge gaps about SHS and its health effects, there was support for smoke-free environments in public places. Subjects might have over-reported their support for smoking regulations in hospitals, schools, public vehicles and offices due to social desirability or some other reasons, but this alone seems unlikely to account for the level of support reported. As for regulations in restaurants and bars, the tendency to over-report was probably stronger because owners were invited to the study by local CDCs or health institutes. However, all subjects were reminded at the beginning of invitations and interviews that smoking prohibition or restriction was not required in hospitality venues and the survey had nothing to do with any form of hygiene inspection. We would expect those owners and managers who opposed to prohibit or restricting smoking to report their opposition due to concerns that support reported by them might facilitate the implementation of smoking bans. Supportive attitudes towards banning smoking in restaurants and bars differed by city. This might be attributed to different scopes of tobacco control initiatives in different cities. Beijing for example was the leading city in tobacco control and had initiated a series of activities on promoting smoke-free