مجله بهداشت و ایمنی کار
سال چهارم شماره 3 (پاییز 1393)

The most common standards being used for predicting the health risks of whole body vibrations are ISO 2631- and BS 6844, presenting frequency weighting anfd different coefficients for different sensivities in variuse axes. In yhis study, vibration was measured about 900 minutes on 9 trains in one of the active lines of tehran metro with the aim of comparing the mentioned standards in evaluating whole body vibation. In this research, in addition to evaluation of different kinds of vibration indicators, the differences of ISO 26331-1 and BS 6841 Standards have also been investigated. The amounts of r.m.s., vibration dose and daily vibration dose were measured in x, y and z axes for drivers seat and x axis for drivers back rest separately according to the instruction of the two standards. The mean calculated values of r.m.s and vibration dose on a basis of 135 6841 standard were lower than those values calculated according to ISO 2631 standard. Moreover, the results showed that 3 cases, based on the ISO standard, had risk level of higher than 17 m/s1.75 and 3 cases, had risk level of higher than 15 m/s1.75 value, provided by BS 6841. Calculation according to the ISO 2631-1 standard show higher values. Indeed, ISO 2631-1 can provide a more secure criterion company to BS 6841, although the 15 m/s1.75 in BS is lower than the highest level of health guidance caution zone in ISO. Additionally, the association between r.m.s and vibration dose values in ISO 2631 is relatively lower than this association in BS 6841.

Emergency situations are of the major challenges in industries. Understading the status of inter-team interaction is effective in improvement of emergency response team (ERT). The purpose of this study was to investigate the interaction space of ERP in a refinery, using the social network analysis (SNA). Methods and Materials: In the present case study, the density indicator was used to examine the interaction space in the ERT. The obtained data were analyzed, employing UCINET 6.0 social network analysis program. The findings showed that the ERT has the relatively low concentration with the density of 0.2 overall, the result reflect a low level of interactions among response reams at emergency situations management. The presented approach provided an appropriate image of interactions network among the emergency response teams. The social network analysis can be used for assessing the interactions of the emergency response teams.

Heat-related illnesses are major causes of morbidity in the world. Workers who are exposed to extreme heat are not be able to activate their compensatory mechanisms and their health will consequently be at risk. Heat stress due to its impact on work performance increases the likelihood of worker disease and injuries and it also affect productivity. During sugar beet harvest, farmers from about 8 am to 4 pm, are exposed to sunlight and excessive heat. Therefore, preventive measures are essential in order to protect the health of farmers and improve productivity. The aim of this project as to study the effectiveness of the rehydration to reduce heat stress and increasing productivity during sugar beet harvest, conducted in 2012. in this project, 20 farmers from sugar beet farmers were studied during summer season, from 8 am to 4 pm in West Azarbaijan- Boukan city where the average temperature and relative humidity were 29.85 0C and 41%, respectively during sugar beet harvest. Selection criteria were defined as working more than 50% of the day’s working schedule and to have worked for at least 10 days of the follow-up period. Individual characteristics and water consumption rate during the work shift and also Production output data by farmers were recorded at the end of the working day. Environmental parameters using a portable monitoring device was measured and recorded and finally, the collected data was used for analysis using spss software version 20. WBGT-TWA index for four the period of the time from morning to afternoon obtained 27.39 0C, as it was greater than the allowable thresholds. Ten workers receive 6-7 L of liquid and harvest production was significantly increased among those who are better hydrated (P=0.005), from 5 to 7 tons of harvest sugar beet per any worker per day, against lower 5 tons for farmers without drinking enough water. Farmers productivity can be increased by applying rehydration measures during work.

One of the factors influencing on indoor air quality of the buildings is performance of HVAC (heating, ventilation, and air conditioning) systems. These systems supply clean and odorless air, with temperature, humidity, and air velocity within comfort ranges for the residents. The aim of this study was to evaluate performance HVAC system in an administrative building in Tehran. A questionnaire, developed in their research was used to assess the building occupants’ perception about the performance of HVAC system. To evaluate the performance of HVAC systems, air velocities were measured in the diffusers using a thermal anemometer. Moreover, CO2 concentration, air temperature and relative humidity were measured in the whole floors of the building. Air distribution inside the building was evaluated using smoke test. Most of the studied people complained about the direction of airflow, thermal conditions and cigarette odor. The highest level of carbon dioxide was measured at 930 ppm inside the restaurant. The maximum and minimum air temperatures and relative humidity were measured 28.3-13.8° C and 28.4-23% respectively. Smoke test showed that the air distribution/direction wasn’t suitable in one third of air diffusers. Improper air distribution / direction was the main problem with the studied HVAC system which could be corrected by adjusting and balancing of the system.

Statistical Report of the Social Security Organization indicate that among the various industries, the construction industry has the highest number of work-related accidents; so that in addition to frequency, it has high intensity, as well. On the other hand, a large number of human resources are working in this whish shows they necessity for paying special attention to these workers. Therefore, risk assessment of the safety in the construction industry is an effective step in this regard. In this study, a method for ranking safety risks in conditions of low number of samples and uncertainty is presented, using gray multi-criterion decision-making. In this study, we first identified the factors affecting the occurrence of hazards in the construction industry. Then, appropriate for ranking the risks were determined and the problem was defined as a multi-criterion decision-making. In order to weight the criteria and to evaluate alternatives based on each criterion, gray numbers were used. In the last stage, the problem was solved using the gray possibility degree. The results show that the method of gray multi-criterion decision-making is an effective method for ranking risks in situations of low samples compared with other methods of MCDM. The proposed method is preferred to fuzzy methods and statistics in uncertain and low sample size, due to simple calculations and no need to define the membership function.

Job design approach is one of the significant concepts in ergonomics Experts believe that integration of macro ergonomics and job design can lead to improved productivity in the organizations. Therefore, this study examined the relationships between job design, performance and job satisfaction. Methods and Materials: This cross - sectional study was done in 11 branches of one of the bank in Hamadan. Job Design Questionnaire, Job Satisfaction Questionnaires and Bank Performance Indicator were used in order to collect data. spearman correlation coefficient was used for determining the correlation between each two variables. This study showed that the motivational approach was the minimum approach (3.8%), and the mechanical approach, was the dominant approach (74.7%) in the study branches and the majority of branches had an average level of job satisfaction. Moreover, there was a significant positive correlation between job design (motivational and cognitive approaches) and job satisfaction. In addition, the results showed that between job design (Motivational approach) and satisfaction were significantly correlated with performance, (p = 0.05). Regarding the role of job design in job satisfaction and employees, performance, it can be stated that job redesign towards a motivational approach and considering the principles of ergonomics in the workplace, can play an important role in efficiency and productivity of an organization.