مجله بهداشت و ایمنی کار
سال ششم شماره 4 (زمستان 1395)

Due to the importance of engineering controls for prevention of microwave exposure, this study was conducted to design and constract a novel electromagnetic shielding and also to examine the factors influencing shielding efficacy in X band frequency range.
Material and This study used Resin Epoxy as matrix and nano-Nickel Oxide as filler to prepare the composite plates with three different thicknesses (2,4, and 6 mm) and four different weight percentages (5,7,9 and 11). The fabricated composites characterized using X-ray diffraction and Field Emission Scanning Electron microscopy. Shielding effectiveness, percolation depth, and percolation threshold were measured using Vector Network Analyzers. Thermal Gravimetric Analysis was conducted to study the temperature influence on weight loss for fabricated composites.
A maximum shielding effectiveness value of 84.18% was obtained for the 11%-6mm composite at 8.01 GHz and the 7%-4mm composite exhibits a higher average of shielding effectiveness of 66.72% at X- band frequency range. The 4mm thickness was optimum and critical diameter for composite plates; and percolation depth was obtained greater than thickness of composites. However, increasing the nickel oxide content did not show noticeable effect on the shielding effectiveness. Thermal Gravimetric Analysis showed that the study shields were resistant to temperature up to 150 °C without experiencing weight loss. What is more, the results indicated that Nickel oxide Nano particles had desirable distribution and dispersion in epoxy matrix and percolation threshold was appeared in low content of nickel oxide nanoparticles.
A novel electromagnetic shield using low thickness and few content of nanoparticle with noticeable efficacy was properly designed and constructed in the field of occupational health. In addition, this shield has low cost, easy to manufacture, resistance to wet/corrosion, and low weight. Epoxy/nickel oxide composite can represents a new generation of electromagnetic shielding, which is considered as a promising candidate for occupational protection against microwave exposure. It is recommended that future studies improve the shielding effectiveness by decreasing the percolation depth and investigate the efficacy of the fabricated shield in the workplaces.

Nowadays, Shielded Metal Arc Welding (SMAW) is the most widely used arc welding. During the welding operation, typically, various harmful agents such as fumes, gases, heat, sound and ultraviolet radiation are produced of which fume is the most important component from the viewpoint of occupational health. The present study aims to compare the number and the mass concentration emitted in SMAW to determine the most appropriate index of exposure to fumes in the welding processes.
Material and In this study, the portable laser aerosol spectrometer and dust monitor of GRIMM, model 1.106, was used to measure the number and mass concentration of fumes emitted from SMAW on 304 stainless steel with a thickness of 0.4 mm. Air sampling was performed at a distance of 41 cm representing the welder’s breathing zone. The measurements of number concentration (NC) and mass concentration (MC) were taken under the condition of 25 volt voltage and direct current of the electrode polarity.
The total NC and MC of welding fumes in welder’s breathing zone was 1140451 particles per liter and 1631.11 micrograms per cubic meter, respectively. The highest number concentration was found to correspond to the particles with 0.35 to 0.5 micrometer-sized distribution (NC1; 938976 particles per liter) and the lowest was related to the particles with 5 to 6.5 micrometer-sized distribution (NC7; 288 particles per liter) and the particles larger than 6.5 micrometer (NC8; 463 particles per liter). Moreover, the highest mass concentration was related to the particles with 0.35 to 0.5 micrometer-sized distribution (MC1; 450 micrograms per cubic meter) and the particles larger than 6.5 micrometer (MC8; 355 micrograms per cubic meter).
The findings indicated that there is no agreement between number and mass concentration as two particles assessment index, and as the particles’ size become smaller, the mismatch of them is becoming more apparent. Since the smaller particles penetrate into the lower respiratory tract and have higher potential for adverse health effects, it is necessary to measure and assess particles in various size distributions and especially the smaller fraction of particles. Therefore, it is thought that considering the mass concentration alone and not paying attention to number concentration in the assessment of exposure to particles in the industrial workplaces and specifically in welding stations will not be reflected valid assessment of adverse health effects of welding fumes as a systemic poison on body organs.

Human error is considered as a crucial challenge in occupational settings. Health care system is amongst occupational environments with high rate of human errors. Numerous preceding studies noted that more than 2/3 of medical errors are preventable. Accordingly, different methods are suggested to evaluate human errors, especially in nuclear industries. The aim of this study was to evaluate the application and accuracy of HEART technique in medical health system.
Material and This qualitative study was conducted in surgical intensive care units of a hospital in Shiraz city. All nurses recorded errors were categorized regarding the given tasks and then all tasks were ranked based on the number of errors. The probability of nurses’ tasks error was estimated through AHP-HEART method and the resultant ranking was compared with the recorded errors. Additionally, the prioritization of contributing factors to errors, determined by AHP and AHP-HEART methods, was compared employing Pearson statistical test.
Based on the results, there was a concordance in the rate of nurses’ error determined by HEART method and the recorded errors. However, no significant correlation was between errors contributing factors determined by AHP and AHP-HEART methods.
This study suggested that although HEART technique was successful to rank the tasks considering the magnitude of error probability, but the coefficients of error producing conditions should be customized for nurses’ tasks in order to provide appropriate control measures.

Positive safety attitude of employees is directly associated with workplace safety, and it can decrease occupational accidents through increasing the number of safety acts. Assessment of employees’ safety attitude in workplaces can be more helpful to identify underlying causes of unsafe acts. The main aim of this study was to assess safety attitude and its’ relationship with different personal and occupational variables in a number of manufacturing companies, located in Urmia City, Iran.
Material and In this study, the safety attitude of 194 employees was measured in 9 manufacturing companies using a questionnaire with acceptable validity and reliability. The questionnaire consisted of two parts: participants’ personal and job related information, as well as 46 safety attitude related questions. The questions of safety attitude was measured using a five-point Likert scale in form of ten main aspects.
The results indicated that majority of participants (78.9 %) had a moderate safety attitude level and the mean (±SD) score of total safety attitude was 3.19 (±0.25). “Commitment to safety and participation in safety activities” and “safety talk and risk information communication” obtained the highest and lowest scores of safety attitude factors, with mean (SD) of 3.97(±0.52) and 2.53(±0.58), respectively. In addition, the participants from private companies showed a better safety attitude than those of governmental companies (P-value Since the majority of participants had a moderate safety attitude, this research suggests the study companies to attempt in order to increase the quantity and quality of safety training courses, as well as safety communication of managers and supervisors with workers for improving their attitude toward safety and subsequently decreasing occupational accidents.

Workers in open pit iron ore mines are exposed to heat stress which can cause health and safety problems. The purpose of this study was to evaluate heat stress among open-pit mine workers of iron ore based on Wet Bulb Globe Temperature (WBGT) index and also to investigate its relationship with physiological Strain.
Material and This cross-sectional study was conducted on 120 healthy miners, working in an open-pit mine, during summer season, in 2014. Physiological parameters, including core body temperatures and heart rate, were measured according to ISO 9886 standard and physiological strain indices, including Physiological Strain Index (PSI) and Physiological Strain Index based on Heart Rate (PSIHR), were calculated using the equation. Environmental variables as well as physiological parameters were simultaneously measured and recorded during work shift. WBGT index was calculated according to ISO 7243 and using the equation. Statistical analysis was performed using the SPSS software version 22.
The mean WBGT index was estimated 29.09oC for workers. “Drilling” and “factory and Krasher” units showed the highest and lowest WBGT index values of 31.06oC and 29.05oC, respectively. Workers occupational exposure to heat stress were higher than recommended thresholds based on WBGT index in all work units. A statistically significant correlation was found between WBGT index and physiological strain indices
(P value WBGT index showed a higher correlation with physiological strain Index; and level of heat stress in all work units of mine was higher than recommended thresholds. Thus, countermeasures should be adopted to control heat stress for the workers in this field.

Annually, many accidents and preventable events happen for the patients hospitalized in treatment centers. Therefore, the related causing factors should be recognized in order to reduce the medical errors. Accordingly, the present study aimed to assess the relationship between patient’s safety culture elements and medical errors and also the ways to tackle them.
Material and This cross-sectional study was conducted among 380 employees working in the education and treatment centers affiliated with Kermanshah University of Medical Sciences in 2015. The hospital version of patient safety culture questionnaire was used for data collection. Data were analyzed by SPSS software, version 19 using different statistical tests including multivariate analysis of variance and Pearson’s correlation.
The patient safety culture was at an undesirable level in the study centers. Of the elements related to safety culture, the lowest positive scores belonged to ‘issues related to employees’, and ‘reporting’ with scores of 23% and 26%, respectively. On the other hand, ‘team working in the organizations’ (59%) and ‘organizational learning’ (57%) obtained the highest positive scores. Fifty-eight percent of the respondents did not report any errors.
The results of present study emphasize on creating a desirable organizational atmosphere, the need for staff participation in various levels of decision making, and creating the culture of reporting errors in order to recognize the causing factors and to promote patient safety culture.

Heat stress is one of the harmful risks in casting and die casting industries, which can not only cause work-related diseases but also can impair the performance and safety of workers. Since the indicators that are used to evaluate heat stress are very different, it is very difficult to choose a suitable index. The aim of this study was to determine the optimum heat stress index in foundry, die-cast, and road construction industries using FAHP and Topsis methods.
Material and In order to determine optimum heat stress index in foundry, die-cast, and road construction industries, first, the prioritization criteria were defined by experts (including ease of measurement, measurement accuracy, comprehensiveness, time, cost, and correlation). Then, considering these criteria, the best heat stress index was determined based on experts’ opinions and using FAHP and Topsis methods.
The results of this study suggest that given the current conditions and criteria, WBGT and P4SR is the best indices for foundry, die casting and construction.
The results showed that according to comprehensiveness, accuracy and correlation criteria, the WBGT index is considered as the best indicator of heat stress assessment in foundry, die-cast and road construction industries. Moreover, the HSI ranked in the last place due to the complexity and cost of its calculation.

A high percentage of musculoskeletal disorders in workplaces occur due to awkward posture and non-ergonomic design of the work stations for lifting and carrying of materials. To avoid these injuries, jobs should be designed in a way that ergonomics risk factors are controlled properly. The aim of this study was to utilize ergonomics interventions to minimize ergonomics risk factors in bag packing unit in a mineral processing plant.
Material and This cross sectional study was carried out among 20 workers of bag packing unit. Camera recording of working postures, evaluation of medical records, interview, and REBA technique were used to identify the ergonomic risk factors. Interventions included changing the conveyor belt height and the use of spring pallets (spring table). Data were analyzed using Paired T-Test by SPSS software version 18.
Before implementing ergonomics intervention, a total of 75% of evaluated postures by REBA technique obtained score of 8-10 (very high risk level) and 25% had score of 11-15 (very high risk level) that correspond to the action level 3 and 4, respectively. Following the implementation of ergonomics interventions, a total of 90% of the analyzed postures showed action level 2 (moderate risk level) and the remainder 10 percent of evaluated postures showed high risk level. Comparison of REBA technique scores before and after implementing interventions showed a significant difference (P-value Based on the findings of this study, the implementation of ergonomics interventions has remarkably decreased the required action level and it may be able to improve work-related postures.