Journal of Health and Safety at Work

The Effects of Heat Stress on Selective Attention and Reaction Time among Workers of a Hot Industry: Application of Computerized Version of Stroop Test

A. Mazloumi

Introduction: Working in hot and inappropriate climate condition is one of the most common problems of occupational health which can lead to heat induced diseases and even death. Heat stress may impair the cognitive processes involved in decision-making and converting simple tasks to complex ones. The aim of present study was to assess selective attention and reaction time among workers in a casting unit of a car manufacturing industry and to investigate the effects of heat stress on mentioned variables.

Material and Method: In this retrospective cohort study 70 workers from a hot industry were selected in two of exposed and control groups. First, demographic questionnaire was completed for each of the participants and noise and light were measured as the likely confounding factors. Stroop test 1, 2, and 3 were done before and during the work in order to determine the effects of heat on selective attention and reaction time. Besides,WBGT were measured at the ankle, waist, and head levels. Data were analyzed using SPSS software, version 18.

Result.: WBGT measurements showed that the mean WBGT were 33 and 16.7 for the exposed and not exposed groups, respectively. Moreover, no significant relationships were observed between test duration, reaction time, and number of errors in Stroop tests 1 and 2 and the level of heat (P-value<0.0001). However, the mentioned variables had a significant positive correlation with Stroop test 3. Additionally, for exposed group variables of test duration, reaction time, and number of errors in Stroop 3 were significantly higher than those of control group.

Conclusion: According to the findings in present study, heat stress causes an increase in reaction time and a decrease in selective attention. Thus, heat can be assumed as a stressor in hot work environments and the heat should be taken into account while design of job and tasks which needed selective attention or reaction time.

Analyzing Hazards using System Theoretic process analysis (STPA) Methodology: A Case Study In The emergency extinguishing systems of Thermal power plant

G.A. Shirali

Introduction: The weaknesses of traditional hazard analysis methods lead to their inefficiency to utilization for modern socio-technical systems. System Theoretic Process Analysis (STPA), which is in the category of systematic analysis methods, has a powerful logic to identify hazards in such systems,as a suitable alternative method. This study aimed to analyze hazards associated with extinguishing systems of steam unit of a power plant, using STPA method.

Material and Method: The present research is a qualitative case study. The related hazards were defined using STPA method.Following, the safety control structure diagrams in different parts were plotted and inadequate control measures and its causal factors were identified.

Result: For steam unit of power plant, the most tragic incidents wererelated to hazards and risks of turbine device (switch the turbine cycle). Then, according to the plotted diagram for structure of safety control extinguishing systems associated with switching the turbine cycle, PLC system was determined as the most important part of the control system and operator was identified as the strategic and effective part of a control system. Following, more than 54 causal factors were identified, considering the relevant details about the risks analysis of the turbine.

Conclusion: Due to its systematic structure,STPA method can be effective for a more complete identification of risks and causal factors which causing hazards in the emergency extinguishing systems. Therefore, development of such tools for those operators involved in safety-critical systems will be useful in terms of safety.

Assessment of Health, Safety and Environment (HSE) indices in an urban vicinity: A Case Study based on Community-Based Initiatives (CBI) in Tehran

Y. Khosravi

Introduction: Neighborhood environment plays an important role in the health of residents. This study was conducted to assess health, safety and environment (HSE) in poor and rich vicinities in order to improve health levels of the neighborhoods, using Community-Based Intervention (CBI) approach.

Material and Method: In the present field study, HSE variables were assessed by a checklist (NHSES) through observation, interviews with neighborhood residents as well as document review.Of the 374 vicinities in Tehran, ten regions were selected through cluster sampling. The Control Chart approach was used in order to compare the field data and the possibility of decision-making about the neighborhoods.

Results: Overall, results showed that status of health, safety and environment in both rich and poor neighborhoods in Tehran was in the warning level.

Conclusion: The CBI is an appropriate model for empowerment of neighborhoodsin a way that promote HSE status.

Evaluating the efficiency of two phase partitioning stirred tank bio-reactor for treating xylene vapors from the airstreamthrough a bed of Pseudomonas Putida

F. Golbabaei

Introduction: Volatile organic compounds such as xylene, which are the main constituents of the oil and petrochemical industries, have serious impacts on health and can cause adverse effects on the environment. It is clear that release of these compounds into the environment should be controlled. The two-phases partitioning stirred tank bio-reactor is one of the newest methods for treating these compounds which have few side-effects besides of having appropriate efficiency since itdestroyscontaminant completely and transform it tosafer compounds.

Material and Method: In this study, a two phase partitioning stirred tank bio-reactor, in lab scale, was used for treating the gas stream containing xylene vapors. The aqueous phase containing the bacteria Pseudomonas putida and nutrients inserted into the bioreactor with 3:1 ratio and system performance was evaluated for 432 hours in the concentration range of 1000 mg/m3 to 3500 mg/m3

Result: Empirical findings of this study showed that the maximum, minimum and average of removal of xylene vapors by stirred two phase bioreactor containing a pure strain of Pseudomonas putida were 94.00, 54.00 and 84.94 percent, respectively.Furthermore, maximum, minimum and average of elimination capacity of xylene were obtained 93.00,24.00 and 62.02 g/m3/h, respectively

Conclusion: Overall, the results of the present research revealed that the application of two phase stirred tank bioreactors (TPPBs) containing pure strains of Pseudomonas putida was successful for treatment of air streams with xylene.

Assessing the match between female primary students’ anthropometric dimensions and furniture dimensions in Hamadan schools in 2013

R. Zare

Introduction: Children have been known to spend most of their time at school. They learn their sitting habits in this period of time. Incorrect sitting postures and inappropriate school furniture can result in abnormalities in the vertebral column, back pain, neck pain, Fatigue and discomfort. Hence, this study was aimed to examine the match between students’ body dimensions and existing benches and desks dimensions in Hamadan female primary schools.

Material and Method: In this study, 624 students of Hamadan female primary schools were investigated and some of their anthropometric dimensions including shoulder height, elbow height, knee height, popliteal height, popliteal-buttock length and hip breadth were measured. In this sense, a chair (with adjustable height, depth and elbow support) and a caliper with movable jaw were used for measurement of anthropometric dimensions. The measurements were performed in a way that thighs were in full contact with the seat, there was a right angle between the thighs and legs, the feet were in full contact with the movable pedal, the trunk was straight and the back and hips were in full contact with the backrest. Following, the match of the dimensions of existing benches and desks with the appropriate dimensions (based on the students’ anthropometric dimensions) were examined.

Result: The results showed that the seat height, seat depth, seat width, back rest height, desk height, underneath desk height were in acceptable rangefor 10.1%, 17.3%, 5.6%, 53.5%, 1.9% and 31.1% of students, respectively.

Conclusion: Despite differences in the body dimensions of primary school students, there is no regularity in using of school furniture. Overall, the dimensions of existing benches and desks are not matched with the anthropometric dimensions of students.

Studying patient safety culture from the viewpoint of staffs in educational hospitals in Tehran City

M. Zakaria Kiaei

Introduction: Patient safety is an important issue in regard to hospital servicesand any problem can cause adverse consequences. The purpose of this study was to assess the patients’safety culture at educational hospitals in Tehran.

Material and Method: The present descriptive-cross sectional study was carried out among 312 health care workers in Baharloo, Amir Aalam, Shariati and Sina hospitals in Tehran, which were selected by cluster sampling. The participants were chosen randomly in each cluster. Safety Culture Survey questionnaire including 12 dimensions was used to assess patient safety culture. Cronbach’s alpha and test-retest coefficient were estimated 81 and 79 percent, respectively.

Result: Nurses comprised 61 percent of participants in the study. 42% of staff had less than 5 years work experience. Of the 12 dimensions of patient safety culture, the frequency of reporting and exchange of information had the minimum average of 56 and 55, respectively. Moreover, the dimensions of organizational learning and expectations-management measuresobtained the highestmean score (69)among 12 dimensions of patient safety culture. Total mean patient safety culture in understudy hospitals was 63.

Conclusion: It should be noted that paying more attention to the patient safety culture can lead to improve hospitals condition, as a whole, and to have a patient-friendly environment. Special attention should be paid to dimensions with the lowest mean score in order to strengthen them.

Ergonomic Interventions in Manual Handling of Carpets to the retail sellers in a textile company

A. A Shafikhani

Introduction: Manual material handling (MMH) is the most common cause of work-related Musculoskeletal Disorders (MSDs). Prevention of MSDs is highly critical. The aim of this study was to assess risk of carpets manual handling by retail workers, and to implement ergonomic interventions in order to reduce risk of MSDs.

Material and Method: This interventional study was conducted among 36 workers in 19 retailer sites of a textile corporation. Ergonomics assessment of the retailers was done using the comprehensive risk assessment model of the British Carpet Foundation. Moreover, the Nordic Musculoskeletal Questionnaire was used to determine the prevalence of workers’ MSDs. Reassessment was conducted after implementation of the ergonomics interventions.

Result: The mean age and work tenure of participants were 36.28 and 16.2 years, respectively. The results of Nordic Questionnaire before intervention showed that overall 37.8% of the workers had experienced pain at least once during the past year, with the highest frequency belonged to the lower back (75%), shoulder (61%), and neck and upper back (55%), respectively. After implementing the interventions, the prevalence of MSDs reduced to 23.5%. The results of risk assessment before and after the interventions showed that of the 19 retailer sites, six sites were improved from poor to average state, and one site showed improvement from average to good condition.

Conclusion: By implementing ergonomics interventions in carpet delivery sites, the risk factors of MSDs, induced by manual carpet handling, were reduced and safety and ergonomic conditions of the retailers were improved, compared to the previous conditions.

Ergonomic Assessment and Design of Electronic Ticket Booths in Mashhad City

H. Razavi

Introduction: Work conditions in kerbside ticket booths intensify the risk of health threats. In this research, it is aimed to introduce solutions for improving ergonomics conditions of these booths, by ranking and analysis the risk factors.

Material and Method: Demographic information as well as physical, mental, and safety conditions of 47 booths are collected through questionnaires, interview and video recording. Following, critical index was identified using a hybrid method including QEC checklist, ANOVA statistical test and innovative methods for determining ergonomic indices. Improvement strategiesfor the critical index were analysed,using CATIA V5 R20 software and RULA technique, and solutions were presented.

Result: Based on F-test at the 0.05 significance level, anthropometric characteristics and personal informationshowed no difference betweenmale and female vendors, except for weight. Comparison of ergonomic indices manifested the maximum occupational exposurefor physical-motor factors (45.39) and environmental factors (41.28). Additionally, the highest risks determined by Nordic questionnaire and QEC checklists belonged to arms and shoulders (38) and wrist (26). Three dimensional model of vender with current and suggested postures were analysed using RULA and accordingly it was found that risk levels were improved for right and left side of the vendor body from 7 and 5 to 3 and 1, and for customers from 6 to 1.

Conclusion: Vendors of electronic ticket booths are exposed to musculoskeletal and environmental health threats, in Mashhad. Relocating the booths, adjustingcounterand desk height can significantly reduce the risk of mentioned hazards