BackgroundThe occurrence of occupational accidents is a serious public health issue in industrial workers and may impose life jeopardizing complications. The aim of the study was to assess the effect of a training intervention based on the theory of planned behavior (TPB) on helmet use of workers in cement factories in Khoy and Urmia, Northwest of Iran.Materials and methodsThis study was a controlled quasi-experimental investigation (before and after) which was conducted on 170 workers employed in Khoy and Urmia cement factories, Northwest of Iran. Eighty-five eligible subjects from Khoy (as intervention group) and 85 similar samples from Urmia (as control group) were selected and recruited. A valid and reliable four-part questionnaire was used to collect the data including socio demographic information, awareness, the theory constructs, and the behavior. After completing the study questionnaire and needs assessment, a specific educational program was implemented on the intervention group only. The effects of education were compared between the groups before and after intervention. The posttest was applied 1 month after educational intervention.ResultsThe mean age of workers in the intervention and control groups was 34.32 ± 8.19 and 33.62 ± 6.17 years, respectively. Before education, the mean score of awareness and helmet use behavior of intervention group was 6.15 ± 3.4 and 5.35 ± 2.8, but after education, those changed into 13.61 ± 3.10 and 9.15 ± 1.65, and the differences were significant (p < 0.01). In addition, before education, the mean score of attitude, subjective norm, behavioral control, and behavioral intention of intervention group was 27 ± 5.17, 37.74 ± 6.92, 29.56 ± 6.17, and 17.65 ± 4.90, respectively. After education, the mean score of those changed into 37.26 ± 4.76, 48.34 ± 5.64, 42 ± 8.07, and 24.79 ± 5.33, respectively, and changes were statistically significant (p < 0.01), while no statistically significant differences were observed in awareness, the behavior, and the theory constructs in the control group after the intervention.Conclusion and recommendationsThe TPB-based educational approach had a remarkable effect on helmet use of workers. Applying this theory to improve workers’ personal protective behaviors is recommended and emphasized.