This present study was believed to be the first study to individually investigate the smoking habits of rural-to-urban migrant workers in Shanghai. A total of 5,380 rural-to-urban migrant workers in 7 districts of the central city, urban fringe zone and suburbs of Shanghai were enrolled, in whom 45.0% of male and 2.0% of female migrant workers reported current cigarette smoking. The gender difference of smoking prevalence in our sample was similar with the previous studies [18,19]. However, our current smoking prevalence of male seemed to be slightly lower than the estimate for a Beijing sample (51.7%) [12] and three cities sample (Chengdu, Shanghai and Beijing) (51%) [20]. The fraction of female smokers in our sample was also significantly lower than that reported by Chen et al. for rural-to-urban migrants in Beijing almost ten years ago (2% vs 10.9%) [12]. These variations in reported rates of smoking in this study with the study by Chen et al. [12] and Yang et al. [20] may be attributed to the different study location, sampling frames, and demographic characteristics of the population enrolled [18]. In addition, the prevalence of current smoking for males in our study was also observed to be lower than the national prevalence reported in the 2010 Global Adult Tobacco Survey (GATS) (52.9%) [2] and the prevalence for general male population in Shanghai (54.8%) [21]. This might result from the lower income of migrants in cities. Migrants belong to the lower socioeconomic rank of cities and always be paid at a minimum wage compared with urban counterparts, causing the huge gap of wages between migrants and workers with an urban residency [22]. According to the Shanghai Bureau of Statistics in 2012 [23], the average monthly income of residents was 4692 yuan, which was much higher than that of the migrants in our study. The economic factor may have reduced the likelihood for many migrants to engage in smoking behaviors in urban areas [24]. Moreover, the main goal of migrants leaving home was to earn money which also makes them more likely to lessen or abandon their smoking behaviors to save more money and send money home [19], thus leading to the lower prevalence of smoking. Previous studies also showed that tobacco smoking prevalence was lower in migrant men than that in the urban and rural residents [19,24].
Three groups of risk factors were found to be significantly associated with smoking in our study. First, occupation was a determinant of smoking risks among rural-to-urban migrants. Female migrants working at construction sites, hotels/restaurants and entertainment venues had 8.8 times, 5.06 times and 6.79 times the likelihood to be current smokers compared with those working in factories. Similarly, the male migrants working at construction sites and entertainment venues had 1.3 times and 1.86 times the likelihood to be current smokers. The increased risk of smoking experienced by migrants working in the construction sector may be first attributed to this high stress job. Exposure to occupational hazards (e.g., chemicals and dust) is a typical job stressor for construction workers, which has been demonstrated to positively affect current smoking [25,26]. Next, construction is a high hazard but low-income occupation, and payment is often delayed or withheld [27]. This results in a lower socioeconomic status among construction workers and makes them more prone to smoking. Thirdly, the gender discrimination from supervisors and coworkers may be a reason for the higher odds of smoking among female construction workers than the male construction workers [25,28]. Thus, tobacco control intervention for this population should consider work-related occupational factors along with individual approaches [25].
The increased odds of smoking among migrant workers employed in hotels, restaurants and entertainment venues may be related to that particular workplace making them more exposed to smoking, resulting in a significantly higher likelihood of smoking [13]. Furthermore, branding and packaging of female specific cigarettes is an effective approach to recommend cigarettes to young women, leading to the substantially higher prevalence of current smoking among women who was exposed to female specific brand cigarettes than those who did not attempt female brands [29]. To prevent these young women from smoking, related regulations should be developed to limit the packaging and advertisement for female targeted cigarettes brands [13].
Second, our study also suggested that migratory history was positively associated with current smoking behavior. For male migrant workers, longer time living in an urban environment correlated with an increased risk of smoking. This may result from the stress caused by long-term separation from family and pressure to establish social relationships, as well as increased exposure to foreign cultures and urban cigarette marketing campaigns [12]. The number of cities they migrated through was also associated with elevated risk of smoking, which may be ascribed to the stress for adapting to new environments and circumstances and the high concern for the unstable living situations and employment opportunities [20]. This seemed to be more severe for male migrants because the more cities migrated, the male migrants were more susceptible to be current smokers.
Last, the regression model showed that migrant workers with unhealthy psychological status (SCL-90 total scores > 160) were at a higher level of risk for cigarette smoking. This supports previous evidence that psychosocial stress was an important risk factor for smoking among urban residents [30]. Navigating life in urban areas, instability of living and employment conditions, discrimination, and lack of social support also can induce a high level of psychosocial stress and high rates of mental problems for migrant workers [31], which in turn increase the susceptibility to cigarette smoking. Special prevention initiatives addressing the need to reduce exposure to psychosocial stress should target rural-to-urban migrants in order to help prevent smoking.
In addition to the above three crucial factors for female and male migrants, the female with high monthly income and the male being divorced/widowed may also be significantly related with the smoking prevalence. Female migrants who earned higher incomes may work in entertainment sectors such as night clubs and thus are more likely to be intoxicated by smoking [11]. Marital termination may lead to a loss of spousal support to buffer against stress and then contribute to increased smoking [32]. A higher age and working at domestic service appeared to be protective factors for smoking. This may be due to the higher wish to quit smoking for a participant with higher age owing to health concerns and the customer requirement for domestic service migrants.
Our findings provide some suggestions for the direction in which tobacco prevention strategies could be targeted to high risk populations of rural-to-urban migrant workers. In our study, 55.2% of current smokers reported their workplace as the location they smoked most often, while only 18.3% migrants reported smoking at public place. In 2010, the Shanghai People’s Congress Standing Committee issued the Smoking Control Legislation in Public Places and totally prohibited smoking in 13 types of public places [33]. The implementation of these regulations further makes smoking at public places decrease somewhat [34]. This might explain the lower smoking rate at public places. However, this legislation is not a comprehensive ban and there is still no mention in the ban of workplaces. Previous studies have demonstrated that restriction of smoking in workplaces is an effective method by which tobacco consumption and exposure to second-hand smoke can be reduced [35,36]. Our data suggests that smoke-free policies in workplaces, in addition to public places, should be broadened and strengthened in China. Integrated healthcare programs should be provided to the migrant population to help them identify relevant risk factors for cigarette smoking and better enable them to stop smoking. In addition, healthcare programs should address stress management as an important component of smoking cessation. This includes the identification of stress risk-factors and appropriate strategies to cope with stressors, which may further reduce smoking behavior.
This study has several limitations. Firstly, we cannot draw conclusions regarding causality and the point estimates as well as associated variance estimates are likely biased because of the cross-sectional design, and non-random, quota sampling selection of participants. Secondly, we studied residents of only one city and cannot generalize the identified risk factors to the overall population of rural-to-urban migrant workers. Thirdly, having utilized a self-reporting questionnaire, our data may suffer from an information bias caused by interviewer expectations. However, since smoking is widely regarded as a normal behavior in China, the self-report bias in smoking research has been previously reported to be minimal [37].
