Background: Exposure to hand-arm vibration is one of the most common physical harmful factors. The purpose of this study was Experimental study of the level of manual performance disability caused by exposure to hand-arm vibration among automobile casting workers. Methods: This study was performed on 53 casting workers as case group and 28 controls as control group. The measurement of the vibration of the worker's arms and hands was carried out in accordance with the ISO 5349 standard. The level of manual performance disability was evaluated using skeletal-muscular, sensory-neural and vascular tests. Also, a questionnaire was used for the level of disability of the arm, shoulder and hand DASH. Data were analyzed using SPSS16. Results: The 8-hour vibration exposure was 8.33 m / s 2 (4.49), which exceeded the permissible level. Skill and dexterity, fingers and grip strength of the dominant hand in the case group were decreased by 4%, 13.3% and 11%, respectively (P<0.05). The regeneration time of the dominant hand in the case group was 41.2% higher than the control group (P<0.05). Sensory-neurological complications increased in the case group compared to the control group, however, it was not statistically significant. The DASH score in the case group was 10.7 (13.4) and the control group was 4.1 (5.1). Conclusion: Hand-arm manual performance disability in workers exposed to vibration decreased from 4% to 14%, which confirmed the DASH score. In addition, workers showed a higher level of vascular complications compared with sensory-neurological complications.
Background: Inadequate lighting in the workplace can cause unconventional changes in the posture of office workers. Poor ergonomic conditions in the office cause inappropriate postures during work and increase pressure on the musculoskeletal system which can cause some disorders in long-term. In this study, the relationship between work environment lighting with the prevalence and severity of musculoskeletal pain among office workers has been investigated.
Background and Objective:Constant exposure to cold is considered a workplace hazard in cold seasons. We aimed to determine the level of cold stress and its relationship with physiological responses in auto mechanics. Materials and Methods:This analytical cross-sectional study was conducted in the winter of 2016 among auto mechanics in Hamadan, Iran. Physiological responses were measured in accordance with the ISO 9886 standard method. Body fat percentage was also quantified using Caliper model 01128, and the thermal resistance of the participants' clothing was calculated in clo using the ISO 9920 standard. Environmental measures such as air temperature and air velocity were measured simultaneously, based on which cold stress indices including wind chill factor and wind chill equivalent temperature were determined. Data were analyzed using SPSS, version 21. Results: The means of wind chill index, equivalent chill temperature, and minimal required clothing insulation (IREQ) were 489.97±47.679 kcal/m 2 .h, 13.78± 1.869°c, and 2.04±0.246 clo, respectively. According to the results of cold stress indices, the studied employees were exposed to cold stress. Pearson correlation test reflected a significant relationship between cold stress indices and physiological responses (P<0.05), however, IREQ showed the highest association with the physiological responses of the subjects. Moreover, there was a significant correlation between body fat percentage and core temperature (P<0.05; r=0.314). Conclusion:The results confirmed that IREQ index has high validity for the estimation of cold stress among auto mechanics. Moreover, the increase of body fat percentage boosts cold tolerance of employees.
Background and Objective: Exposure to noise has harmful effects on physical and mental health as well as the function. Low frequency sound is one of the most important sources of noise in the environment. Some individual differences, such as extroversion, neuroticism, and sound sensitivity are among the factors influencing the effect of sound on cognitive functions. Therefore, this study aimed to investigate the effect of personality type (introversion/extroversion) on cognitive performance in the presence of low frequency noise. Materials and Methods: This interventional study was performed on 120 students of Hamadan University of Medical Sciences. The samples were selected through purposeful sampling (60 extroverts and 60 introverts) and entered the study. The cognitive performance of the subjects was examined using the Integrated Visual and Auditory Continuous Performance test during the confrontation with sound. The data were analyzed by independent t-test and analysis of variance using the SPSS version 20. Results: Results of the present study demonstrate that low frequency sound negatively affects the components of cognitive performances. It was revealed that the cognitive performance declines with an increase of 50 to 70 dB in noise pressure (P<0.05). Furthermore, evaluation of the effect of personality type (introversion/extroversion) and gender indicated that the cognitive performance was significantly more affected in introverts and women, compared to the extroverts and men (P<0.05). Conclusion:The findings of this study showed that increasing in the sound level from 50 to 70 dB led in diminished cognitive performance. In addition, this negative effect is significantly more prominent in introverts and women, in comparison with the extroverts and men. How to Cite thisArticle: Babamiri M, Moatamedzadeh M, Golmahammadi R, Derakhshan J, Farhadian M. Role of Personality Type in the Effects of Low Frequency Sound on Cognitive Performance of the Students. J Occup Hyg Eng. 2017; 4(2): 59-66.
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