Showing papers in "International Journal of Occupational Safety and Ergonomics in 2003"

Affective computing--a rationale for measuring mood with mouse and keyboard.

Abstract: Emotions are an increasingly important factor in Human-Computer Interaction (HCI). Up to the present, emotion recognition in HCI implies the use of explicit or intrusive methods, for example, video cameras or physiological measurements. We are developing and evaluating a method for the measurement of affective states through motor-behavioral parameters from standard input devices (mouse and keyboard).

Reducing Musculoskeletal Discomfort: Effects of an Office Ergonomics Workplace and Training Intervention

Abstract: Effects of an office ergonomics workplace and training intervention on workers' knowledge and self-reported musculoskeletal pain and discomfort were investigated. An instructional systems design process was used to develop an office ergonomics training program and the evaluation tools used to measure the effectiveness of the training program on workers' office ergonomics knowledge and skills. It was hypothesized that the training and workplace intervention would allow the worker to more effectively use their workplace through increased office ergonomics knowledge and skills. Following the intervention, there was a significant increase in workers' office ergonomics knowledge and awareness. Self-reported work-related musculoskeletal disorders significantly decreased for the group who had a workplace change and received ergonomic training relative to a workplace change-only group and a no intervention control group.

Health Risks From Exposure to Metal-Working Fluids in Machining and Grinding Operations

Abstract: Metal-working fluids (MWFs) are used in machining and grinding operations to cool the tool and work, reduce the friction between the tool and work, improve the surface integrity of the work piece, and increase tool life and productivity. Health problems have been reported among workers exposed to MWFs, including incidences of respiratory, digestive and skin cancers, and increased rates of cough and phlegm. This paper reviews and discusses issues concerning health risks from exposure to MWFs in machining and grinding operations, the various factors that influence the degree of exposure, and control methods to reduce exposure to metal-working fluids.

Symptoms and clinical findings from the musculoskeletal system among operators at a call centre in Sweden--a 10-month follow-up study.

Abstract: The musculoskeletal health among 57 operators at 1 call centre in Sweden was studied with 10 monthly follow-ups, parallel to a reference group of 1,226 professional computer users in other occupations. Operators at this call centre were more symptom-loaded than the other professional computer users in spite of their younger age and shorter exposure to computer work. Symptoms were long-lasting or recurrent. Muscle tenderness and nerve affections in the neck- shoulder region were the most common specific findings and diagnoses at medical examination of incident symptom cases. More extensive studies should be done on the working conditions and health status among call centre workers.

The Impact of Participatory Ergonomics on Working Conditions, Quality, and Productivity

Abstract: A participatory ergonomics model was designed for improving working conditions, quality, and productivity in a medium-sized manufacturing enterprise by making use of a Supportive Expert Team (SET)

Evaluation and quantification of manual materials handling risk factors.

Abstract: This study investigated the ability of the Revised NIOSH Lifting Equation (RNLE) to measure the risk of low back injury as verified by employee health outcomes. In addition, several basic risk factors and combinations of risk factors presumed related to low back disorders were explored. The RNLE was modified to allow analysis of one-handed and two-handed, asymmetric lifts. Predictive performance was not changed. Simplifying the RNLE by removing several variables did not significantly reduce the RNLE's predictive performance. These modifications to the RNLE show promise for increasing both the usability and utility of the RNLE.

Visual strain and lighting preferences of VDT users under different lighting systems.

Abstract: Lighting influences users’ visual strain and well-being. Therefore creating lighting that ensures visual work conditions do not result in visual fatigue is a preventive activity. The aim of the study was to model different lighting systems for visual display terminal (VDT) work and to determine their influence on users’ visual strain and preferences. The results of the study showed that visual fatigue was lowest for indirect and compound lighting systems. On the other hand, in general, direct lighting realized by “dark-light” luminaires was the most preferred lighting system. Some interesting differences related to age, gender, and VDT work experience were found. On the basis of the obtained results lighting designers can be provided with some guidance.

Accidents are normal and human error does not exist: a new look at the creation of occupational safety.

Abstract: “Human error” is often cited as cause of occupational mishaps and industrial accidents Human error, however, can also be seen as an effect (rather than the cause) of trouble deeper inside systems

A new approach to the mouse arm syndrome.

Abstract: OBJECTIVES: The study validates a new computer mouse concept. The tested device is a small mouse with a pivoting pen-shaped handle. The hypothesis behind the design is the assumptions that the pen grip requires less static tension than the normal mouse grip and that fine-motor, high precision tasks normally are done with finger movements with forearm at rest.METHODS: Four muscles were monitored with electromyography (EMG) during work with a new mouse and with a traditional mouse.RESULTS: EMG activity was significant lower, in M. pronator teres–46%, M. extensor digitorum–46%, M. trapezius–69%, and M. levator scapulae– 82%, during work with the new mouse as compared to the traditional mouse.CONCLUSION: Altering the design of the computer mouse can significantly reduce muscular tension.

Examining RULA’s Postural Scoring System With Selected Physiological and Psychophysiological Measures

Abstract: The Rapid Upper Limb Assessment (RULA) survey is a posture-sampling tool used specifically to examine the level of risk associated with upper limb disorders of individual workers. This paper examines the relationship between RULA’s postural scoring system and measures of surface electromyography (EMG), self-reports of discomfort, and job attitude questionnaires. Twenty participants each performed a 30-min typing task on a computer in 3 working postures based on RULA’s scoring system. A statistically significant difference was found only in perceived discomfort. The perceived discomfort results demonstrated that RULA was able to identify “high risk” postures. The next question we need to ask is, does perceived discomfort result in tissue damage, or does tissue damage yield discomfort?

An attempt at preventing asthenopia among VDT workers.

Abstract: We report the results of 3 surveys of visual display terminal (VDT) users who took a minibreak during which they viewed a stereoscopic image of a repeating parallel pattern showing planets. The sin...

Emission of dust and gases in tubular cored wire welding of steel.

Abstract: The emission of dusts and gases, which are generated during tubular cored wire welding and which are hazardous to health and the environment, were studied. Tests included various kinds of tubular electrode wires used for welding steel, that is, rutile flux cored wires, basic flux cored wires, and metal cored wires for welding unalloyed, low-alloy, and high-alloy steels as well as selfshielded flux cored wires used for welding low-alloy steels. The research results make it possible to assess the influence of the type of wire and welding conditions on the emission volume and to compare chemical hazards generated during tubular cored wire welding with those typical for other arc welding processes.

Safeguarding crushing points by limitation of forces.

Abstract: Limitation of forces can be a simple measure to safeguard crushing points at doors, machines, and vehicles. In this connection different standards define a threshold force value of 150 N. This widely accepted value refers to static forces only. The dynamic forces that arise from impact on a person are frequently ignored, although they are generally higher than the static forces. The article describes an instrument for the measurement of static and dynamic crushing forces. This instrument has a stiffness that approximates the average stiffness of human fingers as one of the most at-risk parts of the human body with regard to crushing injuries. Sensory tests were carried out to define dynamic forces considered admissible at crushing points.

A study of computer-based task performance under thermal stress.

Abstract: A visual-visual dual computer task was designed to test the effect of the thermal environment on dual task performance. The temperatures selected for testing were 20 and 35 °C Wet Bulb Globe Temperature (WBGT). 34 volunteers were randomly assigned to 1 of the 2 temperature conditions. Individual differences in single task performance were controlled by equating the baselines of single task performance. Once individual differences in single task capacity were controlled, statistically significant differences in performance were demonstrated. Mean accuracy was computed over a 1-hr testing period in each temperature condition. Participants’ mean accuracy in the 35° condition (38.18%) was substantially lower than in the 20° condition (50.88%).

Sitting posture, postural discomfort, and visual performance: a critical view on the interdependence of cognitive and anthropometric factors in the VDU workplace.

Abstract: The study focuses on individual and standard visual display unit (VDU) workplaces with respect to performance and muscular load. Three different work settings were realized: The workplace was either adjusted to individual preferences or to the European standard. The third condition mirrored exactly the individual setting, however participants were told that it was set according to another standard. Dependent variables were visual performance in a search task, the rated muscular load, and individual preferences. Results show that both individual work settings yielded a superior performance as compared to the standard. However, performance and muscular comfort improved when participants knew they had adjusted the workplace. Apparently, VDU users follow a intuitive rationale adjusting their work setting minimizing muscular load and optimizing performance.

The effect of seat design on vibration comfort.

Abstract: A field study was done to evaluate different seat designs in the aspect of minimizing vibration transmission and reducing the level of discomfort experienced by drivers subjected to transient vibration. Two seat designs (sliding or fixed in the horizontal direction) were compared in an experiment based on variation of sitting posture, speed, and type of obstacle. The comparison was done by assessing discomfort and perceived motion and by vibration measurement. Ten professional drivers were used as participants. Maximum Transient Vibration Value and Vibration Dose Value were used in the evaluation. The results showed that a sliding seat is superior in attenuating vibration containing transient vibration in the horizontal direction. It was also perceived as giving less overall and low back discomfort compared to a fixed seat.

Relevance of the EMG/grip relationship in isometric anisotonic conditions.

Abstract: The aim of the present study was to develop a relationship to evaluate grip force using the electromyogram (EMG) in isometric anisotonic conditions.The EMGs of the flexor digitorum superficialis (FDS) and the extensor digitorum (ED) were recorded in 3 flexion-extension positions of the wrist (30° flexion, 30° extension, and 60° extension) associated with 3 positions of the forearm (70° pronation, prono-supination, and 70° supination). For each position, the participants had to follow linear ramp targets (2 rates of increase and decrease) displayed on an oscilloscope.The results show the best fit is a quadratic type force-EMG relationship. Some aspects such as the rate of force variation and the forearm and wrist positions are then discussed along with the limitations of the relationship.

Biomechanical stresses in computer-aided design and in data entry.

Abstract: A study of the risk factors of musculoskeletal disorders (MSDs) of the upper limbs was carried out on 2 populations, 1 performing a computer-aided design (CAD) task and the other performing a data entry task. A questionnaire on MSD complaints and working life was completed by a sample of each population. Biomechanical measurements of the forces, the angles, and the repetitiveness of movements of the upper limbs were carried out on some operators in each sample. It emerged that complaints of the upper limbs seem to be linked to the use of input devices. The grip forces exerted when using the keyboard and mouse were higher in CAD than in data entry.

Comparison between the strain indicator HRV of a head-based virtual retinal display and LC-head mounted displays for augmented reality.

Abstract: Augmented Reality uses Head Mounted Displays (HMD) to overlay the real word with additional virtual information. Virtual Retinal Displays (VRD), a new display technology, no longer requires Liquid Crystal Displays (LCD). VRD technology addresses the retina directly with a single laser stream of pixels. There are no studies on the user's informational strain in this new VRD technology. Various papers have shown that Heart Rate Variability (HRV) is a valid indicator for the user's informational strain. An empirical test revealed no difference in the user's HRV between VRD technology and LCD technology. Consequently, there seems to be a comparable user informational strain regarding the display types.

Ergonomic study on the manual component insertion lines for occupational health and safety improvements.

Abstract: The study aimed at reducing the occupational health and safety problems faced by the manual component insertion operators. Subjective and objective assessments, and direct observations were made in the printed circuit assembly factory. Simple and low-cost ergonomic interventions were implemented, that is, repairing chairs, reducing high workloads, assigning operators to a maximum of 2 workstations, confining machines that emitted bad smell and much noise, and providing finger work aids. The results of the interventions were reductions in operators' work discomforts, that is, chair discomfort (by 90%), high work stress, and discomfort due to profound change in their workstations. Their health hazards were also eliminated, that is, inhalation of toxic fumes, exposure to too much noise, and pain due to pressing sharp components.

Enhancement of drilling safety and quality using online sensors and artificial neural networks.

Abstract: Cutting force sensors and neural networks have been used for the occupational safety of the drilling process. The drill conditions have been online classified into 3 categories: safe, caution, and danger. This approach can change the drill just before its failure. The inputs to neural networks include drill size, feed rate, spindle speed, and features that were extracted from drilling force measurements. The outputs indicate the safety states. This detection system can reach a success rate of over 95%. Furthermore, the one misclassification during online tests was a one-step ahead pre-alarm that is acceptable from the safety and quality viewpoint. The developed online detection system is very robust and can be used in very complex manufacturing environments.

Effect of Subjective and Objective Workload on Asthenopia at VDU Workplaces

Abstract: An ergophthalmological tool has been developed to investigate effects of subjective and objective workload on work-related visual complaints (asthenopia). In field studies on different visual display unit (VDU) workplaces effects of objective and subjective workload, work intensity, and work breaks (5-9 min/hour) could be found. It could be shown that during the first hours of VDU work, asthenopic complaints have the tendency to follow effective workload. With increasing working time the effect of a general and visual fatigue overlaps other reported visual complaints in the majority of cases.

Assessing the compatibility of work system factors through an integrative model: a case study.

Abstract: Work Factor Compatibility (WFC) theory proposes that human performance is dependent on the interaction of various components (e.g., physical and mental task demands, physical environment, social environment) of the work system and integrates multiple human performance perspectives into a single mathematical model. Work Factor Analysis (WFA) is a comprehensive survey administered to employees to determine the WFC index. WFA also provides recommendations for targeting specific work system areas for improvement. Preliminary testing of the tool was conducted at a manufacturing operation of a Fortune 10 company. Results are discussed and recommendations for further study are made.

Resistance of medical gloves to permeation by methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDMA), and 1,4-butanediol dimethacrylate (1,4-BDMA).

Abstract: Gloves afford hand protection by minimizing skin contact The effectiveness of medical gloves to protect against permeation of the monomers, methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDMA), and 1,4-butanediol dimethacrylate (1,4-BDMA), was assessed focusing on permeation rates and degradation of glove materials caused by monomer contact Fifteen different brands of gloves were tested using a European Standard procedure Surface images of glove materials before and after exposure to the monomer mixture were obtained using a scanning electron microscope The standard is not applicable as the only method for estimating the safety of gloves, but it is useful as guideline together with the cumulative permeation of acrylic monomers Monomer contact on the outside resulted in substantial swelling of most glove materials, and structure changes of the inside surface

Prevention of deep vein thrombosis in VDU work.

Abstract: This paper introduces preventive measures against Deep Vein Thrombosis (DVT) during Visual Display Units (VDU) work. Four experiments were conducted in order to address this issue. The effectiveness of the preventative measures was evaluated by measuring foot swelling. The results indicated that the following 3 methods would be particularly effective: (a) occasionally adopting a reclining posture with a footrest, (b) 10-min walking every 50-60 min of VDU work, and (3) stretching. In addition we predicted that taking a deep breath could sometimes be effective. DVT is likely to occur in daily life and its incidence can be related to the long-term postures associated with VDU work. This paper suggests that VDU workers should be aware of the risk of DVT and take preventative measures.

Application of neural networks in active noise reduction systems.

Abstract: Active noise reduction systems based on a control unit in the form of a finite impulse response filter assume the linearity of every single component. Neural networks, which have so far been seldom used in this field, are a kind of a filter with the ability to project nonlinear characteristics of an active noise reduction system. This paper presents some simulation research studies of active noise reduction systems based on neural networks. Also presented are results of the operation of systems with different levels of complexity as well as the influence of different parameters of a neural network and of the system itself on those results.

Reasons for applying innovations for scaffolding work.

Abstract: In this paper reasons for applying and for not applying technical and organisational innovations in scaffolding work are studied. In a participatory ergonomic approach these innovations were developed to reduce problems concerning physical load of scaffolders. In this study reasons for the adoption of the innovations in the scaffolding sector are evaluated in two studies, in 48 companies. More than half of the scaffolding sector in the Netherlands adopted the innovations. Reasons for applying innovations concerned improvement of work and health and satisfaction with usage. The reason for not applying the innovations concerned specific situations, such as offshore work, in which innovations were not applicable.

Visual Costs of the Inhomogeneity of Luminance and Contrast by Viewing LCD-TFT Screens Off-Axis.

Abstract: In this study the anisotropic characteristics of TFT-LCD (Thin-Film-Transistor- Liquid Crystal Display) screens were examined. Anisotropy occurs as the distribution of luminance and contrast changes over the screen surface due to different viewing angles. On the basis of detailed photometric measurements the detection performance in a visual reaction task was measured in different viewing conditions. Viewing angle (0°, frontal view; 30°, off-axis; 50°, off-axis) as well as ambient lighting (a dark or illuminated room) were varied. Reaction times and accuracy of detection performance were recorded. Results showed TFT’s anisotropy to be a crucial factor deteriorating performance. With an increasing viewing angle performance decreased. It is concluded that TFT’s anisotropy is a limiting factor for overall suitability and usefulness of this new display technology.

Work-related research, education, and training in developing countries.

Abstract: Work-related research, education, and training (WRET) have not been widely recognised in many developing countries (DCs) as the most important factor for sustainable workplace improvement. There are many reasons why WRET is still neglected or remains unrecognised. Empirical research, advanced studies, and training abroad do not seem to be cost-effective for many people living in DCs because of enormous obstacles. Therefore, it is not easy to demonstrate that WRET result in workplace improvement in diverse situations in each DC. Taking into consideration poor health and safety in various workplaces, this paper aims to stimulate critical opinions and discussions on WRET, which are yet to be given high priority in the national agenda to ensure industrial production and social progress.

The effects of the level of alertness during the rest period on subsequent performance.

Abstract: The aim of this study was to examine how to take an effective rest to prevent a decline in alertness at work. The relationship between alertness during the rest period and subsequent task performance were investigated. The electroencephalogram (EEG) during the rest period was classified into 3 types, and these types had a significant effect on performance after the rest period. Type 1 (increasing in theta, alpha 2, and beta 1 power) was the best one for carrying out the task, whereas performance gradually declined in Type 3 (no change in EEG activity). In the case of Type 1, the method that would relieve sleep inertia had a more positive impact on performance after the rest period.