摘要：Objectives. We aimed to assess the level of awareness and impact of a social marketing campaign to promote Mexico City's 2008 comprehensive smoke-free law. Methods. Four months after the smoke-free law was implemented but before the campaign launch, we collected data from a population-based, random sample of 961 inhabitants of Mexico City. We analyzed data from 786 respondents who completed follow-up at the end of the campaign to determine campaign exposure and the association between campaign exposure and changes in campaign-targeted knowledge and attitudes. Results. Recall of any of the 5 campaign materials was 69%, with a uniform distribution of exposure to 1, 2, and 3 or more campaign materials (25%, 25%, and 19%, respectively). Exposure to a greater number of campaign materials was associated in a monotonic relation with campaign-targeted knowledge of ammonia and arsenic in cigarette smoke. In models assessing support for, perceived benefits of, and perceived right to smoke-free places, campaign exposure accounted for a positive change in half of the indicators within each of these domains. Conclusions. Social marketing campaigns can reinforce knowledge and attitudes that favor smoke-free laws, thereby helping to establish smoke-free norms. Smoke-free policies protect nonsmokers and workers from the harmful effects of secondhand smoke, 1 , 2 contribute to the denormalization of smoking, 3 – 5 and decrease consumption. 6 Mass media campaigns may contribute to the success of smoke-free policies; however, evaluation of their impact is rare, has involved weak study designs, and mainly exists outside of the peer-reviewed scientific literature. 7 Smoke-free workplaces and public places, and accompanying media campaigns, are critical components of the World Health Organization's Framework Convention on Tobacco Control, which promotes evidence-based interventions to combat the global tobacco epidemic. 8 To help provide such evidence, the current study involved a longitudinal evaluation of a social marketing campaign to support a smoke-free law in Mexico City. Media campaigns that focus on the health consequences of secondhand smoke exposure are critical to comprehensive tobacco control programs. 9 Most campaigns of this type aim to increase not only awareness of the dangers of secondhand smoke but also support for smoke-free laws before their passage. For example, the influential California Tobacco Control Program emphasized the dramatic consequences of secondhand smoke exposure, particularly its impact on children, as a means of catalyzing local jurisdictions to implement smoke-free policies. 10 The California program has reduced secondhand smoke exposure, increased the social unacceptability of smoking, 10 reduced tobacco consumption, 6 , 11 and produced health gains. 12 However, the comprehensive nature of the California Tobacco Control Program 13 and the use of multiple campaign messages, including messages on manipulation by the tobacco industry, 10 inhibits evaluation of the particular impact of secondhand smoke campaign messages. A review of the unpublished literature on secondhand smoke campaigns internationally indicates other design problems with how this type of campaign has been evaluated in other settings as well. 7 A second campaign genre aims to promote support for and compliance with smoke-free laws once they have been passed or implemented. 14 – 16 Before a law's implementation, some campaigns have informed people of the rationales behind and timing of the upcoming law. After the law's implementation, positively framed media campaigns often remind people of the law's benefits or thank smokers for helping with its successful implementation. Widespread public support for and compliance with smoke-free laws has been found in jurisdictions where such media campaigns have been aired 15 – 17 ; nevertheless, these studies have not assessed campaign impact above and beyond the impact of the law itself. To inform the evidence base around the implementation of successful smoke-free interventions, as well as to increase understanding of media campaigns that address social norms in general, we evaluated a media campaign to support smoke-free legislation in Mexico City. In February 2008, Mexico City passed a smoke-free workplace law that prohibited smoking in all enclosed public places and workplaces, including public transportation, restaurants, and bars. 18 , 19 One month before the law entered into force on April 3, 2008, the Mexico City Ministry of Health and civil society organizations disseminated pamphlets and radio spots on the health consequences of secondhand smoke exposure and on the timing of the upcoming law. This campaign lasted for 2 months. Media coverage of the law was extensive, with issues framed similarly to how they are framed in high-income countries: the dangers of secondhand smoke exposure versus the greater risks of smog and the law's roots in puritanical US culture; the government's obligation to protect the health of nonsmokers and workers versus discrimination against smokers and the slippery slope of regulating behavior; the neutral or positive economic benefits of the law versus certain economic losses (JF Thrasher, SE Llaguno-Aguilar, and AC Dorantes-Alonso, unpublished observations, November, 2010). 3 , 18 , 20 Nevertheless, most print media coverage was either positive or neutral, with a smaller percentage of overtly negative coverage (JF Thrasher, SE Llaguno-Aguilar, and AC Dorantes-Alonso, unpublished observations, November, 2010). 20 On the eve before the law was implemented, approximately 78% of Mexico City adults supported prohibiting smoking across all enclosed workplaces and public places. 21 Support and attitudes in favor of the law increased another 9% to 13% after the law was implemented. Much of this change happened during the postimplementation period, and it was accompanied by increases in compliance with the law. 14 The social marketing campaign aired during the postimplementation period may have helped to account for these changes. As with other public health campaign evaluations, 22 in the current study, we used data from a representative cohort of Mexico City adults to determine (1) whether the campaign achieved meaningful levels of exposure and (2) whether people most heavily exposed to the campaign were more likely than were those with lower exposure to change campaign-targeted attitudes and beliefs in favor of the smoke-free law.
