مجله بهداشت و ایمنی کار
سال هفتم شماره 3 (پاییز 1396)

Teaching has been reported stressful. Although, the majority of teachers aren’t anxious or unmotivated and they even consider their job valuable and satisfying. Job demands-resources (JD-R) is a comprehensive model in occupational stress domain that simultaneously examines the stressful and motivational aspects of occupations and their related outcomes. Accordingly, the objective of this paper is to investigate job characteristics of teaching (job demands and job resources) and their subsequent outcomes by utilizing proposed model.
Material and This study was a cross-sectional design among 247 high school teachers in Tehran city who were selected by two-stage cluster sampling in spring and summer of 1391. Three aspects of job demands (pupil misbehavior, work-family conflict, and cognitive demand), 2 aspects of job resources (supervisory support and job condition), emotional exhaustion, vigor, teacher’s illness symptoms, and organizational commitment were assessed using job demands-resources model. The data were analyzed by means of SPSS 21 program and path analysis by using AMOS 23 program.
According to the results, model fit indices were in acceptable range and all the coefficient paths were significant (p Based on the findings, fostering initiatives with priorities of firstly regulating job demands and secondly improving job resources can be effective strategies to reduce job related burnout and promoting job engagement, health and organizational commitment of teachers

Hexavalent chromium (VI) is a very strong oxidizing agent that, despite its many uses in various industries, duration of the exposure can lead to lung cancer, deep wounds (in the hands, arm, tongue and palate), nasal septum perforation, burning and inflammation in the nose, lung and upper respiratory tract, asthma, contact dermatitis, damage to the kidneys and liver, and skin allergy. This study aimed to determine the activated carbon efficiency in chromium adsorption (VI) from air flow and its effective parameters.
Material and In this experimental study, chromium mists were generated by a nebulizer (3A model, Italy). Performance of activated carbon in the Cr (VI) adsorption and its influencing factors such as air flow rate (1 and 3L/min), the initial Cr concentration (0.05, 0.15, 1 and 10 mg/m3) and bed depth (2.5, 5 and 10 cm) were investigated. Yoon-Nelson and Thomas models were used to predict performance of adsorbent column and correlation test was used to determine accordance between the model and actual data.
Activated carbon adsorption capacity increased with increasing of bed depth but decreased with increasing of flow rate and inlet concentration. The results showed that the Yoon-Nelson and Thomas models with a correlation coefficient above 0.9953 matched with the experimental data.
The results indicated that activated carbon has a high efficiency in Cr (VI) adsorption, so that its efficiency at flow rate of 3 L/m, depth of 5 cm and concentration of 20 TLV and TLV was 85.42 and 71.83 percent respectively.

Population growth and urban fast development caused increase production of all kinds of solid waste. And, street sweepers are exposed to a variety of risks and toxins by nature of their job for actual and potential. The aim of this study was to identify and to assess the risk factors of accidents and diseases threatening the health and lives of street sweepers in Tabriz city, Iran, and to propose practical solutions to control and remove them in order to promote health and safety and better efficiency.
Material and This study is a descriptive-analytical type, which was conducted over a period of three months in 1393 among 150 street sweepers working in five city areas (areas 2, 5, 6, 7 and 9) of Tabriz. Data was collected through customized questionnaire. Content validity of the questionnaire was performed in the form of quality using a panel of experts and reliability through Cronbach’s alpha. Data after collecting were analyzed by SPSS-16software.
The results showed that 48/7% of people have experienced at least one incident in the past two years. Records of disease showed that back pain with 20/7% and then skin problems whit 7/10% whit highest prevalence and kidney/bladder disease and thyroid whit 0/7% had lowest incidence. Musculoskeletal disorders symptoms percent have, respectively, in the hands, waist, legs highest and in elbow and knee least amount. Research findings showed that 50/70% of the study population, with a mean score of 168/82 have poor health and safety conditions, 21/71% of people have moderate condition and 81/26% of people have unfavorable condition. Among the components of health and safety respectively, components of clothes and other personal protective equipment and psychological problems with a high percentage of 80 percent, one of the most undesirable components of safety and health and components of periodic medical examinations and safety and health training programs were desirable.
The results showed that more than half of street sweepers (70/50%) had undesirable health and safety condition. Shortages or lack of use of personal protective equipment and psychological problems among these workers was evident more than other issues and need for substantial measures in this regard

Resilience engineering is a novel approache to risk management and is the inherent ability of a system to adapt their work before, during and after the changes and adverse events in such a way that maintain the system performance under predictable and unpredictable conditions. The aim of this study was to identify indicators of organizational resilience of refineries and ranking them using fuzzy TOPSIS technique.
Material and A qualitative study was done to identify organizational resilience indicators of refinery complex. The main method of data collection was semi-structured interviews. Indicators were determined using qualitative content analysis and literature review. Weighting and ranking identified indicators was performed using fuzzy TOPSIS technique.
Eleven indicators were identified as follows: management commitment, performance management system, flow of information/communication, involvement culture, error management culture, education, preparedness, flexibility, innovation culture, change management, and human resource management.
Critical sociotechnical organizations especially refinery complexes in order to improve safety management and resilience situation should focus on effective indicators. Monitoring and improving them will increase safety and the resilience level of organization

Heat stress is one of the Hazardous physical agents in the workplace, which can cause impairment of cognitive performance. The current study aimed to evaluate the effect of different levels of heat stress on attention and reaction time in a laboratory condition.
Material and This experimental study was done among 33 students included 17 males and 16 females. Mean age of the participants was 22.1(SD=2.3). Attention and reaction time parameters were evaluated using the continuous performance test and reaction time measurement device respectivlely, after exposure to different heat levels (22°C and 37°C). Data were analyzed using ANOVA test and SPSS 20 software.
The results of tests attention and reaction time showed that the average of attention percentage was decreased and the average of reaction time increased by increasing the heat level, with a statistical differences of (P˂0.001) in both cases. Attention percent in terms of exposure to 22°C temperature was significantly higher than 37°C (P˂0.001). But, reaction time was significantly higher than with the exposure to 37°C temperature than 22°C (P˂0.001).
The results of this study showed that, heat by increasing reaction time and decreasing attention leading to an impairment in the individual’s cognitive performances. Therefore, in jobs such as control rooms and various industries that need attention, concentration and quick reaction, it is necessary to consider and optimize the heat conditions in order to increase the level of attention and decrease of reaction time.

Application of inherently safety principle in the early phase of the design process is very efficient, as this approach is an economic and high efficiency method. While a complete information is not available in the initial phases of the process, the use of valid index to evaluate inherently safety can be efficient. In this case, the best route to design safer process can be selected by comparing the quantitative results.
Material and The comprehensive index to evaluate the inherently safety design (ISD) and cost evaluation of the implementing inherently safety design (ISDC) were studied using a three-step hierarchical matrix screening in this research. Utilizing the proposed inherently safety index, Acetic acid production process and cost resulting from ISD were evaluated. Dimensions of the Matrix for ISD and ISDC included: 1) quadrature inherently safety design vector, 2) location vector of inherently safety design and 3) quantity parameter vector of inherently safety design.
In order to optimize the implementation of inherently safety design and its cost, three hypotheses were used. From them, the idea of using two processes with half capacity and also using 50% Methanol were selected as a design with the highest level of inherently safety and a design with the lowest-cost process, respectively.
In these evalustions the total score for the assumptions of the inherently safety index 1, 2 and 3, were 55,70 and 135, respectively. And the total cost assumptions 1, 2 and 3, have been estimated 858,000, 746,000 and 803,000 US dollars, respectively. Therefore, this tool could show the impact of various scenarios in inherently safety design and also the contrast between the four principles of ISD and its impact on safety and cost factors can be analyzed using an alternative system supplier of methanol.

Correspondence analysis method and preparation of accidents and occupational hazards pattern is able to predict and anticipate accidents and is automatically prioritize the risks and injuries. The aim of this study was to present accidents and occupational hazards pattern based on risk-injury groups, which use it to manage of occupational accidents.
Material and The report of occupational accidents, registered in the social security organization was collected in a period of ten years from 2005 to 2015 (222,300 accidents). Types of risk and injuries to any of the accidents specified based on International Labor Organization criteria and risk of injury were classified in a matrix (18 × 18). Risk-injury groups were separately identified using correspondence analysis and collapse process, as patterns of accidents and occupational hazards. In the mentioned patterns, the relationship between risks and damage can be identified, as it facilitates decision-making in risk assessment in companies covered by the social security organization.
According to the findings, three groups of occupational accidents were obtained and variables of these three groups extracted from the obtained patterns. The first group included six risks and seven injuries that the risks variables were: contact with hot materials, accidents caused by caustic and corrosive substances, contact with chemicals, accidents caused by toxic substances, contact with electrical equipment, explosion and fire, and injuries were: burns, other injuries, multiple injuries, gas poisoning, suffocation, poisoning, environmental hazards. The second group included seven risks and six injuries that the risks variables were: accidents caused by displacement, projections of fragments or particles, accidents caused by machine tools, slipping, falling people, falling objects, other accidents and injuries were: twists and sprains, dipping the objects in the body, objects in the eyes, cuts and amputations, superficial wounds, deep wounds. Finally, the third group included five risks and five injuries that risks variables were: Falling under the rubble, accident with vehicle, accidents caused by displacement, colliding of persons against objects, projections of fragments or particles, accidents caused by manual tools, trapped between objects, accidents caused by machine tools and injuries were: fractures, dislocation, back pain, hitting, contusions and crushing. It should be noted that the study of these patterns can be used to identify and prioritize of occupational accidents.
The proposed groups make new opportunities for development of the applications to analyze, interpret and automate management of occupational accidents in order to minimize uncertainty and increase its objectivity. Its advantage over other similar analyses can be considering both the risks and injury and to obtain groups of two variables. Due to the frequency and distribution of mass of risk and injury variables in the groups, the risk and injury variables of group 3 are the most important, and the risk and injury variables of group 2 are less important and the risk and injury variables of group 1 have the least importance.

Despite the ongoing efforts to reduce human errors in various systems, errors and unsafe behavior are the main cause of accidents in the workplace. Many studies have been conducted to identify and improve human error in recent years. The number of studies about the human error with the variety of topics has made it an overall overview difficult for researchers. Therefore, a systematic review of previous studies can be the best way to share useful findings and make a trend for the future research in the field of human error.
Material and After a systematic search of valid databases, the analysis was focused on the title, publication year, journal title / Congress, city/region, the level of organization, job search, type of organization and the methods used. And articles were evaluated based encryption.
Three groups of human error studies were identified. The first group studies in safety management, safety assessment, and safety planning have investigated the human error. The second group has examined the influence of individual characteristics such as behavior, cognition, and education on human error. The third group has focused on data arise from the previous accident to improve behavior and reduce human error. To make a better orientation for next studies two essential aspects included chronological analysis and thematic analysis was considered.
This study made an attempt to identify the gaps in the studies related to human error and afford some appropriate strategies.