1. Background

Smoking raises the rate of morbidity and mortality, causes early death, and is a significant and avoidable risk factor for cancer [1]. Worldwide, tobacco smoking brings about vital health risks, and it has claimed the lives of around six million individuals [2]. Every year, more than half a trillion dollars are spent to compensate for the financial losses brought on by the consequences of tobacco usage [3]. There are several uses for tobacco, including chewing, smoking, and hookahs [4]. It has long been known that smoking has its negative effects [5]. Moreover, smoking causes damage to all of the body’s organs and is the primary cause of the majority of cancers, including kidney, lung, and cervical cancer [6]. It also increases the risk of heart attacks, strokes, and other cardiovascular diseases [7].

Approximately 1.1 billion individuals worldwide, or one-third of all adults over the age of 15, suffer from a smoking addiction. Of these, five million pass away each year from smoking-related issues they provide [8]. In 2020, 22% of the world population use tobacco [9]. Despite a significant decline in smoking prevalence in recent years, 1.1% of Canadians aged 12–17 and 11.4% of those aged 18–34 reported current cigarette use in 2021 [10]. In 2021, tobacco, cigarette, and hookah use in Iran was 14%, 9.3%, and 4.5%, respectively [11].

Studies show that most smokers started smoking during adolescence [12]. The pattern and trend of smoking in Iran are also very interesting, to the extent that the age of starting to use it during adolescence and between 13 and 18 years old has been reported [13]. According to the World Health Organization, over 24% of 15-year-old students globally smoke [14]. In Iran, however, the prevalence of smoking among teenagers varies significantly, ranging from 2.5% to 17%, depending on differences in study definitions, sample age groups, and research locations [15]. These variations illustrate the growing challenge of addressing smoking among Iranian youths. Studies by Ayatollahi et al. [16] and Mohammadpoorasl et al. [17] further emphasize that smoking prevalence among teenagers in Iran is alarmingly high, underscoring the urgent need for targeted preventative measures.

In 1987, Fishben and Ajzen proposed the theory of planned behavior (TPB) [18]. In this approach, three factors—attitude toward the conduct, subjective norms, and perceived behavioral control—predict the intention to undertake a behavior. Attitude regarding the actions is a behavior’s appraisal, whether positive or negative, and is based on two substructures: behavioral beliefs and an assessment of the behavior’s outcomes, determining the behavior’s attitude [18]. Subjective norms are the imagined social pressure an individual feels to engage in or refrain from engaging in the desired activity. People frequently do actions based on what they believe other people to be thinking, and those in close relationships with them may have an impact on their intention to accept a behavior [18].

According to this theory, a person’s subjective norm is the result of their motivation to follow the goal action in spite of these expectations multiplied by their normative views. In this situation, someone feels a lot of pressure to use drugs if they think—rightly or wrongly—that close friends and family support the experimental use of drugs [18]. Tavousi et al. [19] used this theory to forecast teenage substance misuse; they demonstrated that the structures account for 36% of the intention and 28% of the behavior. Mirzaei et al.’s [20] use of this theory also explained the variation of 17.9% of fathers’ conduct in preventing drug addiction in their children. Bashirian et al. [21] have employed the TPB to predict substance usage in teenagers, demonstrating that attitudes are behavioral controls over substance use as well as subjective standards. Huang et al. [22] demonstrated attitude, subjective norms, and perceived behavioral control in first-year Taiwanese high school students utilizing the TPB as an addiction prevention program, which was successful.

Nevertheless, a large proportion of earlier research has focused on a limited sample size [23–26], within a narrow age group [23, 25–28], or between in danger groups [24, 25], showing the significance of knowledge [23, 25, 27, 28]. Prior research has produced varying outcomes when examining the impact of the interventions [23, 25], underscoring the need for more comprehensive research. To address these gaps, this study investigates the impact of a TPB-informed educational program on a larger, more diverse sample of adolescents aged 14–19 years—a critical age range where smoking initiation is highly likely. By employing a structured, theory-driven approach that incorporates key psychological and social factors, this research is aimed at providing a clearer understanding of the effectiveness of TPB-based interventions in preventing smoking. This approach offers a more robust framework for addressing the rising trend of teen smoking in Iran, with the potential for broader applicability to similar populations worldwide.

2. Methods

This pretest–posttest research with a control group took place in 2022. The statistical population was male students aged 14–19 from Jahrom City, Iran.

The 300 participants were randomly allocated into experimental and control groups, with 150 individuals in each group. A stratified randomization method was employed to ensure balanced allocation based on key demographic variables such as age and smoking status. Participants were first categorized into strata based on these variables, and random numbers were generated using a computer-based randomization tool to assign individuals to either the experimental or control group. Inclusion criteria specified male students aged 14–19 years who had never smoked or had not smoked in the past year and had not received prior training in smoking prevention. Exclusion criteria included refusal to continue participation in the study or missing more than one training session. Informed consent was obtained from all participants prior to their inclusion in the study.

3. Results

The findings of the study indicated that no significant differences were observed between the experimental and control groups in terms of demographic characteristics such as age distribution, father’s occupation, monthly income, or education level, confirming the homogeneity of the groups at baseline (Table 2). Similarly, no significant differences were detected in baseline smoking-related variables, such as smoking duration, between the two groups (p > 0.05).

After the intervention, significant improvements across all constructs of the TPB were observed in the experimental group when compared to their preintervention scores. These improvements included increases in knowledge (from 10.89 ± 1.21 to 13.49 ± 1.64), attitude (from 33.85 ± 1.23 to 51.69 ± 4.69), subjective norms (from 4.52 ± 1.81 to 6.38 ± 1.86), perceived behavioral control (from 18.38 ± 3.32 to 31.13 ± 1.54), behavioral intention (from 6.93 ± 2.75 to 8.33 ± 2.87), and smoking prevention behavior (from 6.75 ± 2.74 to 8.53 ± 2.68) (p < 0.001 for all comparisons). In contrast, the control group exhibited minimal changes in these constructs, with differences in postintervention scores that were not statistically significant, as shown in Table 3.

Statistical analyses revealed that the differences in the postintervention scores between the experimental and control groups were significant for all constructs of the TPB (p < 0.001). These results suggest that the educational intervention based on the TPB had a substantial impact on improving the psychological and behavioral constructs related to smoking prevention.

When the results were analyzed within the framework of the TPB, the intervention was found to significantly influence behavior-related variables, including attitude, subjective norms, perceived behavioral control, and behavioral intention, even after controlling for knowledge-related variables and their changes. This approach allowed for a more precise understanding of the intervention’s impact, demonstrating that the observed changes in smoking prevention behavior were not solely due to increases in knowledge but were also influenced by changes in other core TPB constructs.

Overall, the findings indicate that the TPB-based educational intervention was effective in promoting smoking prevention behavior among male high school students in the experimental group, highlighting the value of using a theory-driven approach to address behavior change in this population.

4. Discussion

This study is aimed at assessing the effectiveness of an instructional program based on the TPB in preventing smoking among male students in Jahrom schools, Iran. The findings demonstrated a significant increase in the experimental group’s knowledge about smoking after the intervention compared to the control group. Previous studies, such as those by Mohammadkhani and Rezaee [30], have identified that students with lower social skills are more likely to smoke. Similarly, Ramzankhani et al. [31] found that nonsmoking students tend to possess higher levels of knowledge about the risks of smoking. These findings align with evidence showing that a lack of information is associated with higher tobacco use, while greater knowledge is linked to a stronger rejection of smoking [32]. Therefore, education plays a critical role in increasing awareness and dispelling misconceptions about smoking, which is a key step toward reducing smoking behavior. Addressing incorrect beliefs about smoking, such as the illusion that life without smoking is less enjoyable, can make the journey to quitting both more feasible and satisfying.

The intervention also revealed a significant improvement in the participants’ perceptions and attitudes toward smoking, as reflected in the TPB constructs. Within the cultural context of the study, smoking is socially disapproved of, particularly among young individuals and students, as it is viewed as a behavior that transgresses societal norms and often serves as a precursor to substance dependency. By acquiring life skills through the educational program, participants demonstrated an enhanced ability to manage peer conflicts, cope constructively with challenges, and regulate their impulses. These findings are consistent with research indicating that improved cognitive coping mechanisms reduce the likelihood of engaging in smoking and substance misuse [33].

A considerable increase in the subjective norms related to smoking was observed in the intervention group compared to the control group. This reflects the positive impact of the program in reducing the social acceptability of smoking among peers. Subjective norms, a key component of the TPB, are influenced by the perceived attitudes of friends, family, and other significant individuals. The intervention helped diminish the perceived social pressure to smoke, as students were less likely to consider smoking as a socially acceptable behavior [20]. These findings are supported by Jafarabadi et al. [34], who emphasized the importance of designing educational interventions to influence the attitudes of peers and family in order to reduce social norms supporting smoking.

The program also demonstrated a strong influence on perceived behavioral control, which refers to an individual’s belief in their ability to regulate or avoid smoking. Participants in the experimental group showed significant improvements in their confidence to refrain from smoking compared to the control group. According to the TPB, individuals who perceive greater control over their ability to quit smoking are more likely to successfully do so. This finding highlights the importance of fostering self-control and empowering students with strategies to resist smoking, consistent with prior research [35].

The intervention further resulted in a significant increase in the intention not to smoke among the experimental group. This indicates the effectiveness of the TPB-based approach in reducing students’ inclination to smoke. The results suggest that a combination of education and persuasive strategies can effectively influence behavioral intentions, ultimately leading to a reduction in smoking behaviors.

Overall, the study findings align with previous research, such as Mohammadi et al. [36], which demonstrated that TPB-based educational programs improve attitudes, subjective norms, perceived behavioral control, and intentions related to smoking cessation. These findings provide strong evidence that structured, theory-driven interventions can lead to meaningful behavioral changes and contribute to the prevention of smoking among adolescents.

5. Conclusion

The findings showed the impact of the TPB-based educational program on smoking avoidance behavior. Consequently, the program designed to avoid smoking can make advantage of this notion.

Enhancing individuals’ awareness and sensitizing them to smoking-related problems, as elucidated by the educational approach for smokers, have positively influenced their behavior. The findings indicate that employing education grounded in the TPB, which highlights crucial psychological factors in behavior modification, can enhance smoking knowledge, negative attitudes, subjective norms, perceived behavioral intention and control, and overall smoking prevention behavior. Consequently, when smokers get adequate and accurate knowledge, coupled with a favorable attitude toward the manageability of smoking, they choose to embrace healthier practices.

Ethics Statement

Ethics approval was secured from the Ethics Committee at Shiraz University of Medical Sciences (IR.SUMS.SCHEANUT.REC.1400.096). All students gave written informed consent. Approval was secured to digitally document all interviews. Informed consent must be obtained from legally authorized representatives for the participation of individuals under the age of 16 in the study. Confidentiality and anonymity were maintained. The ethics committee approved the consent procedure, as the study is observational and adheres to the guidelines outlined in the declarations of Helsinki.

Conflicts of Interest

The authors declare no conflicts of interest.

Author Contributions

T.R., S.K., A.K., A.Y., and A.K.J. contributed to the study’s conceptualization and design, supervised data curation, analyzed the data, and did the writing. S.K. and A.K.J. conceptualized and designed the study, contributed to data analysis, and reviewed the manuscript. T.R., S.K., A.K., A.Y., and A.K.J. contributed to the conceptualization of the study and conducted a review of the text. All authors reviewed and endorsed the final version. All authors contributed significantly to the research presented in the manuscript, endorsed its claims, and consented to authorship.

Funding

This research did not receive any specific grants from funding agencies in the public, commercial, or not-for-profit sectors.