The overall prevalence of youth TC in the three selected countries was below 10% with significantly higher rates in the males. A comparison can be made with the prevalence rates of other countries reported in . The rates reported in this study were lower than those in other South-Asian countries like Bhutan (18.3% in males, 6.3% in females) and India (16.8% in males, 9.4% in females), comparable to Pakistan (12.4% in males, 7.5% in females), but higher than Maldives (8.5% in males, 3.4% in females). The three selected countries also had higher youth TC rates than some neighboring countries such as China (7.1% in males, 3% in females), but lower than Myanmar (22.5% in males, 8.2% in females) and Thailand (21.7% in males, 8.4% in females). Consistent with the findings on other South-Asian and neighboring countries, this study showed significantly higher TC prevalence among the males. The overall TC among female youths in the countries selected for this study was between 5-6%, but self-reporting in the survey and conservative social structure in these countries may lead to under-reporting of the actual situation. It should also be noted that the male–female differentials in TC prevalence rate in the three selected countries were much lower than those of some countries reported in , including Bhutan, India, Myanmar and Thailand. It is expected that in near future TC among female youths will be high in this region . This assumption about female TC may be due to the overall impact of globalization, urbanization, marketing efforts of the tobacco industry, and changing status of women from higher educational attainment and better employment opportunities [5, 16]. Our findings are supported by the theory of triadic influence  and other studies [5, 17].
In contrast with other studies [5, 10], parental TC in the selected countries did not show any effect on their children’s tobacco usage. However, in accordance with some studies [4, 8, 24–26], the likelihood of TC increased significantly among youths who had witnessed others smoking at home and public places. This ETS exposure not only created health hazards but also influenced them to initiate TC. Such exposure impacted more on the Nepalese and Sri Lankan youths compared to their counterparts from Bangladesh.
Having seen friends using tobacco products increased the likelihood of TC among youths [5, 7, 15]. In line with some empirical evidence in the literature and theories, this study showed that the risk of TC were 2 to 4 times higher due to peer influence. This could be due to imitation, peer pressure or group characteristics. Peer influence had the largest impact on TC in Nepal than in Bangladesh and Sri Lanka.
Easy or sometimes free access to tobacco products and lack of restrictions on sales to minors increased the possibility of TC among youths [4, 27, 28]. Law enforcement, whether in or outside school compound, and tobacco control measures are essential [1, 12, 14]. Of the three countries, strict enforcement of law was most evident in Sri Lanka. This country had the lowest percentage of youths that were offered free samples by tobacco vendors, and those who had seen tobacco advertisements on hoardings, bus stops and rail stations. In contrast, Nepal had the highest incidence of tobacco sample handouts and tobacco advertisements. On tobacco control measures, Sri Lanka also appeared to have done the most through education of TC hazards. Bangladesh, on the other hand, had lagged behind the two other countries in educating the youths on the adverse effects of tobacco use in schools.
Consistent with other findings, this study showed that free tobacco products from vendors had significantly influenced TC behavior of the Bangladeshi and Sri Lankan youths. This may be related to other factors such as school environment [11, 17], cultural norms [5, 17], socio-economic reasons [8, 16] and psychological factors [23, 27]. Although free tobacco products were relatively easier to obtain in Nepal compared to the two other countries, the Nepalese youths were not as easily influenced, perhaps due to different level of knowledge, attitudes and awareness. For the same reasons, incorporation of health issues and hazards of smoking in school lessons had a higher positive impact on the Nepalese youths. Knowledge about the danger of addictive tobacco behavior significantly reduced future TC [8, 9]. This study found that class lessons on the danger of smoking and discussions of smoking and health as part of school lessons had reduced tobacco usage among the youths in all three countries.
Data limitations and future direction
The GYTS was based on self-reporting and therefore, is subject to recall bias and deliberate misreporting. Even though anonymity was emphasized by the WHO officials and efforts were made to assure confidentiality, respondents may have under- or over-reported their actual smoking status given that TC is not a widely acceptable social norm in the South-Asian region. In addition, GYTS is a school based survey that reflects the opinion of students about TC, which may not represent the views of all the youths, especially of those who are not schooling. In order to overcome such difficulties and to ensure data reliability, collected data could be verified by biomarkers using cotinine or exhaled carbon monoxide assessments. These techniques will be useful for obtaining more accurate responses. The variables utilized for statistical analysis were limited to those available in the dataset. However, there may be other important variables that were not considered. A qualitative study is suggested to supplement the understanding of the determinants of the tobacco use behavior among youths. Since the data is cross-sectional, causal relationships cannot be inferred.