Introduction: Musculoskeletal disorders are a major part of occupational diseases in working environments. The aim of this study was to evaluate the risk factors of musculoskeletal disorders by the Muscle Fatigue Assessment (MFA) method. This study also sought to determine the effects of an ergonomic intervention on the mentioned risk in an assembly industry. Methods: This study was conducted on 15 people working in the assembly line. Medical records of assembly line workers were reviewed and Nordic Musculoskeletal Questionnaires (NMQ) after one year of intervention. Activities of these workers in the assembly line were evaluated by the Muscle Fatigue Assessment method (MFA) and workers were given the necessary training. Data were analyzed using the SPSS-16 software. Results: The initial evaluations showed that neck, back, leg and knee, respectively in 6.67, 20 and 13.33% were in "very high" priority corrective measures. Re-assessments after the intervention showed that percentage of people with musculoskeletal disorders in the neck in the "very high" corrective actions changed to zero. The percentage of organs, with "high" corrective actions before the intervention, was greatly reduced. For example, a reduction was recorded around the waist from 60% to 33.33% and neck from 53% to 26.27% after the intervention. A total of 30 cases of abnormalities were detected before the intervention, and after the intervention this number reduced to 11. conclusions: According to MFA score, risk of musculoskeletal disorders was reduced by intervention in this industry and according to Questionnaire, prevalence of musculoskeletal disorders was also significantly reduced.

Background and Objective: The advancement of technology reduced the physical presence of workers in workplace. However, in many work places, man is still the most important and critical element. A human error due to unsafe acts in most of occupational environments can lead to a disaster. Materials and Methods: This qualitative case study was conducted to identify and evaluate human error in the entire mining tasks in 2016. In the first section of this study, all the tasks were studied using Hierarchical Task Analysis (HTA) method and then related possible errors were assessed using a technique for human error analysis (ATHEANA). Results: According to the results of HTA, there were nine major mining tasks and explosion was the main scenario. According to ATHEANA, the possibility of human error for each of basic events was calculated as 0.001. Because there were 13 base events and the occurrence probability of each of them was estimated at 0.001, finally, the total possibility of human error in mining operations was calculated as 0.013. Conclusion: The results of this study showed that explosion in a mine had five sub-tasks that sparked of cigarette wrappers, hand grasping, and inappropriate size and material, respectively, with the probability of defect of 0.004 and 0.003 were the most prevalent errors. Therefore, it is recommended to managers and authorities to take necessary measures to protect the health of them and reduce the risk of human error and environmental conditions.