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Objective@#This study was to understand the current situation of long working hours and identify the association of long working hours and job stress and depression among workers from one district company of state grid. @*Methods@#The project was done with the cross-sectional survey. All questionnaires were completed by self-administered with informed consent. Employees’ weekly working hours was reported by themselves; Using the PHQ-9 scale to assess depression, the JDC Model to evaluate job stress, and SPSS software to analyze data, the single factor chi-square test and multivariate Logistic analysis were performed to identify the association between long working hours and job stress, depression. @*Results@#there were 35.3 percent employees with over 44 hours a week. The association between increasing weekly working hours and job stress and depression was statistically significant. Compared to the reference group (≤44 h) , for those who worked more than 44 hours per week, the odds ratio of job stress was 2.02 (95%CI=1.27-3.23) times increased, and the odds ratio of depression was 1.60 (95%CI=1.01-2.55) times increased, especially for those (≥60 h) , the odds ratio was 3.69 (95%CI=1.45-9.41) and 2.76 (95%CI=1.09-7.03) respectively. @*Conclusion@#Long working hours can significantly increase the risk of job stress and depression among workers. When their weekly working hours exceeds 60, long working hours will be the independent risk factor for both job stress and depression.
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Objective@#To explore the relationship between job stress, work engagement and depressive symptoms of State Grid workers, and to analyze the mediating effect of work engagement between job stress and depressive symptoms. @*Methods@#A cross-sectional survey was conducted to investigate 845 employees from a State Grid company, using the brief job stress questionnaire, the Patient Health Questionnaire (PHQ-9) and 9-item Utrecht Work Engagement Scale (UWES-9) in March 2017. @*Results@#The average score of work engagement was 4.49±1.42, the mean value of job stress was 1.15±0.33, the average score of depressive symptoms was 6.44±4.30, and the positive rate of depressive symptoms was 66.9%.There was a negative correlation between work engagement with both job stress and depressive symptoms (r=-0.193, -0.397, both P<0.01) , and job stress was positively correlated with depressive symptoms (r=0.260, P<0.01) . The relationship between job stress and depressive symptoms was partly mediated by work engagement, and the mediating effect accounted for 27.2% of the total effect. @*Conclusion@#The work engagement of State Grid staff acts as the mediator between job stress and depressive symptoms, alleviating the depressive symptoms caused by job stress.
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OBJECTIVE: To examine the level of occupational exposure to whole body vibration( WBV) in a hydroelectric power station,and evaluate its effects on workers' health. METHODS: A hydroelectric power station in Hangzhou City was chosen as study subject by using judgment sampling method. The level of WBV exposure to workers and high vibration level areas were measured,and the vibration frequency was analyzed. The comfort and allowing duration of occupational exposure in WBV exposed workers was evaluated. RESULTS: The median root-mean-square of accelerometer acceleration of WBV exposure in generator floor,turbines-floor,middle-floor,hydraulic floor of the hydroelectric power station were 0. 894,0. 995,1. 095 and 0. 904 m/s~2,respectively. The central frequency of WBV in this station was 1. 25 Hz. Among the 105 monitoring spots,8. 6% of WBV exposed workers of the spots did not perceive or feel uncomfortable,but 91. 4%of them felt uncomfortable or very uncomfortable. Only 12. 4% of the WBV exposed workers tolerated more than 8 hours of WBV occupational exposure. CONCLUSION: There is an occupational hazard of WBV in this hydroelectric power station.The low frequency vibration with central frequency below 1. 25 Hz is the key control point of the WBV of this hydroelectric power station.
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Objective To compare the effectiveness of two kinds of defluorinating agents (bone char and modified clay) for removal of fluoride in drinking water,and to analyze their application feasibility in small towns.Methods Influencing factors on defluorinating efficiencies of the two kinds of defluorinating agents under the same conditions were studied,namely the effects of adsorption time,temperature,pH,common anions and cations,and solid-liquid ratio on defluorinating efficiencies were studied.The defluorinating efficiencies of the two kinds of defluorinating agents were validated by original groundwater in Jilin Province.The homemade bone char defluorinating agent and modified clay defluorinating agent were regenerated by NaOH and Al2(SO4)3,respectively,and their regeneration abilities were investigated.Results The adsorption data of the two kinds of defluorinating agents were fitted Langmuir model well,and the maximum adsorption capacities were 10.225 g/kg(bone char) and 0.587 g/kg(modified clay).The effect of temperature on defluorinating efficiencies was limited,with increasing temperature(10-35 ℃),the adsorption capacity of bone char and modified clay for fluoride ranged from 1.568 g/kg to 1.598 g/kg and 0.423 g/kg to 0.470 g/kg,respectively.Fluoride could be easily removed under low pH conditions,with increasing of pH(4-10),the adsorption capacity of bone char and modified clay for fluoride decreased from 1.598 g/kg to 1.523 g/kg and 0.724 g/kg to 0.320 g/kg,respectively.The defluorinating efficiencies were improved by common cations(Ca2+) in groundwater,and the adsorption capacity of bone char and modified clay for fluoride increased to 1.713 g/kg and 0.485 g/kg,respectively.Whereas,the defluorinating efficiencies were inhibited by common anions(HCO3-,SO42-) at a certain degree,and the adsorption capacities of bone char and modified clay for fluoride were decreased to 1.158 g/kg(HCO3-) and 0.237 g/kg(SO42),respectively.Defluoridation bone char could be regenerated by soaking in NaOH,and modified clay by immersion in Al2(SO4)3.The adsorption capacities of the two defluorinating agents that had been regenerated for three times still reached 94.6％ and 97.3％ of their original capacities.Conclusions Both of the homemade bone char defluorinating agent and modified clay defluorinating agent have good defluorinating efficiencies and can be regenerated for many times,which are perfectly suitable for application in small towns since they are simple and can be easily applied.The homemade bone char defluorinating agent is suitable for family drinking water and the homemade modified clay defluorinating agent would be more suitable for centralized drinking water.