Iranian Journal of Ergonomics

Study of occupational exposure to non-ionizing radiations and the effectiveness of personal protective equipment in common arc welding processes

Zahra Moradpoor

Introduction: Welding is considered to be one of the main sources of occupational exposure to non ionizing radiations. The present study was conducted to examine the rate of occupational exposure to non-ionizing radiation in common welding processes.

Materials and Methods: In the present descriptive analytical study, occupational exposure to different types of non-ionizing radiations including electromagnetic fields with extremely low frequency and ultraviolet and infrared radiations were examined in five types of arc welding processes at the welding department of the technical and vocational training center of Malayer. Electric field intensities and magnetic field intensities were measured using the HOLADAY HI-3604 instrument and based on the ANSI/IEEE Std 644-1994 method. Ultraviolet and infrared radiation intensities were measured using Hagner-EC1 radiometer (made in Sweden).

Results: Electric field intensities and magnetic field intensities were lower than the exposure limits in the different types of welding processes examined. Nevertheless, the intensity of UV-B radiation exposure was higher than the exposure limits in the different types of welding processes examined, while UV-A radiation exposure was only higher than the exposure limits in arc welding. The results of measuring UV radiation intensities transmitted through protective goggles revealed the acceptable shade number of the lenses used. However, welders' clothing did not provide adequate protection. Moreover, the results showed that welders' infrared radiation exposure degree was much lower than the exposure limits.

Conclusion: The intensity of exposure to non-ionizing radiations was influenced by the type of welding process taken. Given the overexposure of welders to UV-B radiation in unshielded conditions, wearing clothes with an Ultraviolet Protection Factor of 50 is necessary for providing better protection.

Lighting conditions and vision status in carpet weaving workshops and workers at the city of Takab in 2013

Leila Gheibi

Introduction: Due to their long work hours at environments with poor lighting, carpet weavers are at a risk of developing certain eye diseases. Improving health conditions and safety in the workplace, in particular supplying good lighting to carpet weaving workshops as an important environmental factor, is crucial to the health of carpet weavers.

Materials and Methods: The present descriptive, analytical, cross-sectional study was conducted in rural carpet weaving workshops in the city of Takab. A total of 86 carpet weaving workshops were selected through the cluster sampling method with 222 carpet weavers employed in them. General and local lighting settings were measured in carpet weaving workshops using an LX-13 photometer and the vision status of the workers was then determined through an E chart. All the data were ultimately analyzed in SPSS-16.

Results: A total of 48.6% of the carpet weavers suffered from poor vision. The workshops examined had a minimum area of 9m² and a maximum area of 56m², with interior surfaces often brightly colored. In the majority of the workshops, general lighting settings (in 82.4%) and local lighting settings (in 91.9%) were below the standard. All the carpet weaving workshops studied had windows.

Conclusion: The results of this study showed that, in the majority of the workshops studied, lighting settings were both quantitatively and qualitatively undesirable and non-standard. In addition, lighting distribution was non-uniform in these workshops. Reduced lighting significantly increases the prevalence of poor vision. In order to reduce eye injuries among carpet weavers during their years of working, artificial lighting systems must be designed for and implemented in carpet weaving workshops that suit the industry standards.

The Relationship among Quality of Work Life, Participation and Stress Levels in Health Center Workers

Marzieh Mortezaei

Introduction: The quality of work life is one of the main issues in human resource management that is related to job satisfaction, resignation, turnover rate, personality and job stress. The present study was conducted to investigate the quality of working life in relation to stress levels and participation in health care workers in cities.

Materials and Methods: The present cross-sectional study was conducted on 124 random health care workers employed in centers across the city of Hamadan. Walton's quality of work life questionnaire, Belcher's participation questionnaire and a stress questionnaire were used for achieving the study objectives. The Pearson test was used for determining the correlation between the variables.

Results: The results showed that 40.3% of the subjects reported their overall participation rate to be low, 38.7%% reported it to be moderate and 21% reported it to be high. In addition, 73.4% of the subjects reported low levels of perceived stress and 26.6% reported it to be very high. The findings of the study showed a significant positive correlation between participation and the quality of work life (r=0.33 and p<0.001). The quality of work life and stress were also found to have a negative correlation (p=0.015 and r=-0.219).

Conclusion: Through understanding participation and levels of stress among the employees and through presenting and implementing appropriate strategies for reducing stress and encouraging participation, the quality of work life and ultimately the productivity of health care organizations can be increased.

Estimation of forces exerted on the lower back in manual load lifting using 3DSSPP software

Alireza Choobineh

Introduction: Manual load lifting is the most common and most stressful activity in manual handling of loads that imposes the highest possible amount of biomechanical pressure on the body, particularly on the spine. The present study was conducted to determine the prevalence of musculoskeletal disorders and to estimate the mechanical force exerted on the lower back in workers responsible for manual load lifting.

Material and Methods: The present cross-sectional study was conducted on 120 workers responsible for manual load lifting activities in 7 industrial settings in the city of Shiraz. The Nordic Musculoskeletal Questionnaire (NMQ) was used for determining the prevalence of musculoskeletal disorders and the 3DSSPP software was used to estimate the forces exerted on the lower back during load lifting. Data were then analyzed in SPSS-19.Findings: The results showed that lower back problems constitute the most prevalent musculoskeletal disorder (68.3%). Evaluations conducted in 3DSSPP showed that in 17.5% of the cases, compressive forces, and in 10.8% of the cases, shearing forces exerted on the L5-S1 disc were higher in the workers than the permissible levels. There were no significant differences between the rate of the prevalence of lower back pain at different levels of compressive and shearing forces exerted on the disc (p>0/05).

Results: This finding might indicate the limitations of the method used in this study for conducting a comprehensive assessment of loads exerted on the spine.

Conclusion: The prevalence of musculoskeletal disorders, in particular lower back pain, was estimated to be high among the subjects studied. The risk levels of compressive and shearing forces exceeded the permissible amount in a low percentage of the workers studied. The 3DSSPP software might have certain limitations in the assessment of the pressure exerted on the spine.

Design and fabrication of a personal digital assistant (PDA) prototype for postural assessment using RULA, REBA and QEC techniques

Ghasem Hesam

Introduction: The analysis posture methods are counted as a source of investigating the risk of musculoskeletal disorders related to work. Personal digital assistant is a small mobile system with an operative system that can install on various programs such as posture analysis methods. Method: Firstly, three ways for posture analysis such as QEC, RULA and REBA determined. Afterward, the program of posture analysis methods written by BASCOM software with Basic language in IC MICRO CONTROLLER belong to AVR family, and interned in IC by programmer for making PDA. PDA Usability evaluated by Persian version of system usability scale questionnaire after specifying the validity and reliability of questionnaire. Finally, postural analysis was compared using a PDA with paper method. Results: The system usability scale of PDA method is 84.2±6.2 which that got B rank and placed in very well situation. Cronbach's Alpha and Pierson correlation coefficient belongs to System usability Scale are 0.716 and 0.888, sequentially (p˂0.001). The comparison between PDA and paper methods show us that time’s operation for analysis posture in PDA method is less than half of the time in papers method. Also, the probability of calculation errors in PDA is zero, but in paper method has tolerance between 2.33 to 8.66. Conclusion: Use of personal digital assistant for analysis posture solved the problems related to delay achieving to final results and removed the error probability in final results.

Evaluating human errors in cataract surgery using the SHERPA technique

Chiman Saeidi

Introduction: Human errors result in numerous accidents in healthcare professions every year and lead to the death of many patients. Considering the high rate of eye cataract surgeries performed in Iran and the sensitive nature of the surgery, the present study was conducted to identify and assess possible human errors in the performance of these surgeries.

Materials and Methods: The present qualitative, cross-sectional study was conducted to identify and assess human errors in the process of eye cataract surgery using the SHERPA technique. At first, using the hierarchical task analysis method, the surgery process was divided into tasks and sub-tasks. In the next step, through the same technique, possible human errors were detected and risk-assessed. Appropriate prevention solutions were then proposed for reducing the risk of errors.

Results: A total of 53 possible errors were detected for the 41 tasks in the surgery process. The highest error percentages pertained to performance and the lowest pertained to retrieval. Moreover, the risk of 22.64% of the errors detected was deemed unacceptable.

Conclusions: Given the severity of the outcomes of human errors in cataract surgery, reducing the rate of the detected errors is crucial. According to the type and frequency of the detected errors, the findings of the present study emphasize the importance of designing and implementing behavior-based safety training programs for ophthalmologists.

Internal lighting in girls' schools across Hamadan in 2006 and 2014

Mohammad Hajiakbari

Introduction: In an educational environment, the quality of vision is integral to educational progress. Creating visual comfort and increasing efficiency and the desire to study are among the benefits of adjusting the lighting in classrooms and preventing visual impairment in the students. The present study was conducted to evaluate the degree of internal lighting in girls' schools across Hamadan in 2006 and 2014 so as to help identify their potential problems.

Materials and Methods: The present study was conducted in girls' schools across Hamadan on two different occasions –in 2006 and 2014. On each occasion, the average general and local lighting on the classroom blackboards were measured by the recommended methods of the Illuminating Engineering Society of North America on non-sunny days using a Lux Meter and were then compared to the standard limits recommended in the Health and Safety Code of schools and by the Illuminating Engineering Society of North America. In addition to the degree of lighting, certain quality assessment criteria were assessed, including the lighting layout, lamp maintenance, contrast, internal surface cleaning, lighting system maintenance, type of lamps and technical suitability of the design.

Results: Taking the criteria for favorable lighting conditions into account, less than 25% of the sites examined had favorable lighting on both occasions in 2006, only 16% of the classes had favorable general lighting and in 2014, the degree of lighting fell to an unacceptable range in all classes and only 6% of the entire classroom were covered by a standard degree of local lighting on the blackboard. The results also show that surface reflection coefficients are within the desirable range.

Conclusion: The lack of favorable general and local lighting on the blackboard at schools in 2014 and its comparison with the results of the 2006 lighting assessment indicate that providing standard lighting is still a problem for schools. Improper lighting layouts and the use of incandescents or inappropriate light bulbs are among the major causes of poor lighting conditions in girls' school across Hamadan.

Validating the perceptual strain index for the evaluation of heat strain under hot laboratory conditions

Habibollah Dehghan

Introduction: The incidence of heat stress is one of the most common problems in work environments as well as many different industries. The exposure of workers to heat results in heat strain. The purpose of the present study was to validate the Perceptual Strain Index through determining its relationship to the Physiological Strain Index and the Wet Bulb Globe Temperature Index under hot laboratory conditions.

Materials and Methods: The present cross-sectional study was conducted on 15 men in five different temperature conditions (21, 24, 27, 30 and 35ºC) in a climate chamber and on the treadmill with three different activity levels –light (2.4km/h), medium (4.8km/h) and heavy (6.3km/h). Participants' heart rate and oral temperature were measured in order to calculate the Physiological Strain Index, and their thermal sensation and the rate of perceived exerted activity were measured for calculating the Perceptual Strain Index. The correlations between the indices were then evaluated using Pearson's correlation test and the regression analysis.

Results: Pearson's correlation test showed a significant correlation between the Perceptual Strain Index and the Physiological Strain Index (P=0.001 and r=0.94). The Perceptual Strain Index was also found to have a significant correlation with oral temperature and heart rate (p=0.001 and r=0.78 (p=0.001 and r=0.90). In addition, a significant correlation was found between the Perceptual Strain Index and the Wet Bulb Globe Temperature Index (p=0.001 and r=0.71) however, no relationship was observed between the Perceptual Strain Index and the Body Mass Index (p=0.79 and r=0.0009).

Conclusion: The findings of the study showed that the Perceptual Strain Index can be used for evaluating heat strain in the absence of access to other methods of evaluating heat stress as it has an acceptable correlation with valid indices of heat stress.