So far, no study has been done to determine the frequency of seatbelt use on the buses in Iran. While the use of seatbelts in cars is fairly acceptable in Iran, the results of this study showed that only 86 percent of passengers do not always use a seatbelt on the bus. Most people using seatbelts on the bus reported they would do this only at police stations, and at other times they would prefer not to use a seatbelt. Accordingly, it can be said that passengers do not consider seatbelt use as a protective behavior and use it solely to prevent the legal punishment of the police at stations. In light of this finding, it seems that in the design of seatbelt use promotion interventions on the bus, more attention should be focused on in-person factors such as knowledge and attitude. On the other hand, lack of control and supervision over the seatbelt use by the police (like other cars) will weaken the adoption of this preventive behavior by passengers; therefore, it can be concluded that the change in monitoring mechanisms for using seatbelts on the buses is also one of the areas that needs more research and intervention.
The results of this study showed that one unit increase in the subjective norms score increases the likelihood of a seatbelt use on the bus by 25%. Şimşekoğlu et al. also introduced subjective norms as a strong predictor of the behavior of seatbelt use in taxi passengers . According to this finding, it can be said that passengers, who believe that certain people, such as the driver, traffic police, parents, and friends confirm the use of seatbelt on the bus and have motivation to meet their expectations, will have positive subjective norms and the likelihood of this behavior will increase in them, while on the other hand, passengers who believe that others do not confirm the use of seatbelt on the bus will have negative subjective norms and, obviously, the behavior will be undermined in this situation.
The environment was also one of non-behavioral factors in which one unit increase led to 18% higher likelihood of seatbelt use. In this study, the role of the environment in the use of seatbelts by passengers was associated with some factors, such as available belts, easy access to them, as well as the safety of the belt, since many passengers have attributed seatbelt use to these factors. In other studies, the importance of access to non-defective seatbelts in the vehicles has been also mentioned [19-21].
According to self-reports of seatbelt use on the urban roads, perceived barriers are a strong predictor of this behavior . Logistic regression results in this study showed that perceived barriers were also a strong predictor of the use of seatbelts on the bus, so that one unit increase in the perceived barriers score would increase the chance of seatbelt non-use on the bus by 9%. Perceived barriers are the factors that prevent people from performing health behaviors. The results of this study showed that many passengers did not use a seat belt for reasons such as annoyance, stiffness, embarrassment, sweating especially in hot seasons, body pressure, and limitation of movement. In some studies limitation of movement, stiffness of the seatbelt, feeling hot, and sweating have been mentioned among the serious barriers to the non-use of seatbelts [18, 22, 23], which are consistent with the findings of this study. It should be noted that in other health behaviors, such as the use of helmet in cyclists, perceived barriers were also the most important predictor .
The results of this study showed that in the first and second models, observational learning logistics regression has a reverse and significant relation with the behavior of seatbelt use on the bus, while the study by Kuhn et al. showed that observational learning is one of the effective factors in seatbelt use . Observational learning means learning how to perform new behaviors through interpersonal interactions or through the media, and specifically through peers or in other words, the acquisition of the behavior by observing the actions of others . This finding can be justified by the fact that in the present study, the adoption of a seatbelt use behavior is more influenced by other psychological perceptions of individuals, such as perceived barriers, rather than observing others' behaviors. On the other hand, imitation is the essential basis of observational learning, and this is more decisive in children than in adults. Therefore, considering that most bus passengers are from an adult group and the adoption of preventive behavior in this group is less affected by imitation, it could be another justification for this finding.
One of the significant limitations of this study is the self-declaration of completing the questionnaire. Also, considering that one of the criteria for entering the study was reading and writing literacy, the results of this study were limited to the literate population and the illiterate population was ignored.