Tablet form factors and swipe gesture designs affect thumb biomechanics and performance during two-handed use.

Tablet computers' hardware and software designs may affect upper extremity muscle activity and postures. This study investigated the hypothesis that forearm muscle activity as well as wrist and thumb postures differ during simple gestures across different tablet form factors and touchscreen locations. Sixteen adult (8 female, 8 male) participants completed 320 tablet gestures across four swipe locations, with various tablet sizes (8″ and 10"), tablet orientations (portrait and landscape), swipe orientations (vertical and horizontal), and swipe directions (medial and radial). Three-dimensional motion analysis and surface electromyography measured wrist and thumb postures and forearm muscle activity, respectively. Postures and muscle activity varied significantly across the four swipe locations (p < .0001). Overall, swipe location closest to the palm allowed users to swipe with a more neutral thumb and wrist posture and required less forearm muscle activity. Greater thumb extension and abduction along with greater wrist extension and ulnar deviation was required to reach the target as the target moved farther from the palm. Extensor Carpi Radialis, Extensor Carpi Ulnaris, Flexor Carpi Ulnaris, Extensor Policis Brevis, and Abductor Pollicis Longus muscle activity also increased significantly with greater thumb reach (p < 001). Larger tablet size induced greater Extensor Carpi Radialis, Extensor Carpi Ulnaris, Flexor Carpi Ulnaris, Flexor Carpi Radialis, and Abductor Pollicis Longus muscle activity (p < .0001). The study results demonstrate the importance of swipe locations and suggest that the tablet interface design can be improved to induce more neutral thumb and wrist posture along with lower forearm muscle load.

Multilevel model of safety climate for furniture industries.

BACKGROUND: Furniture companies can analyze their safety status using quantitative measures. However, the data needed are not always available and the number of accidents is under-reported. Safety climate scales may be an alternative. However, there are no validated Portuguese scales that account for the specific attributes of the furniture sector. OBJECTIVE: The current study aims to develop and validate an instrument that uses a multilevel structure to measure the safety climate of the Portuguese furniture industry. METHODS: The Safety Climate in Wood Industries (SCWI) model was developed and applied to the safety climate analysis using three different scales: organizational, group and individual. A multilevel exploratory factor analysis was performed to analyze the factorial structure. The studied companies' safety conditions were also analyzed. RESULTS: Different factorial structures were found between and within levels. In general, the results show the presence of a group-level safety climate. The scores of safety climates are directly and positively related to companies' safety conditions; the organizational scale is the one that best reflects the actual safety conditions. CONCLUSIONS: The SCWI instrument allows for the identification of different safety climates in groups that comprise the same furniture company and it seems to reflect those groups' safety conditions. The study also demonstrates the need for a multilevel analysis of the studied instrument.

Workplace ergonomics in lean production environments: A literature review.

BACKGROUND: Lean Production Systems (LPS) have become very popular among manufacturing industries, services and large commercial areas. A LPS must develop and consider a set of work features to bring compatibility with workplace ergonomics, namely at a muscular, cognitive and emotional demands level. OBJECTIVE: Identify the most relevant impacts of the adoption of LPS from the ergonomics point of view and summarizes some possible drawbacks for workplace ergonomics due to a flawed application of the LPS. The impacts identified are focused in four dimensions: work pace, intensity and load; worker motivation, satisfaction and stress; autonomy and participation; and health outcome. This paper also discusses the influence that the work organization model has on workplace ergonomics and on the waste elimination previewed by LPS. METHODS: Literature review focused LPS and its impact on occupational ergonomics conditions, as well as on the Health and Safety of workers. The main focus of this research is on LPS implementations in industrial environments and mainly in manufacturing industry workplaces. This is followed by a discussion including the authors' experience (and previous research). RESULTS: From the reviewed literature it seems that there is no consensus on how Lean principles affect the workplace ergonomics since most authors found positive (advantages) and negative (disadvantages) impacts. CONCLUSIONS: The negative impacts or disadvantages of LPS implementations reviewed may result from the misunderstanding of the Lean principles. Possibly, they also happen due to partial Lean implementations (when only one or two tools were implemented) that may be effective in a specific work context but not suitable to all possible situations as the principles of LPS should not lead, by definition, to any of the reported drawbacks in terms of workplace ergonomics.

Economic evaluation of occupational safety preventive measures in a hospital.

BACKGROUND: When an organization performs an integrated analysis of risks through its Occupational Health and Safety Management System, several steps are suggested to address the implications of the identified risks. Namely, the organization should make a detailed analysis of the monetary impact for the organization of each of the preventive measures considered. However, it is also important to perform an analysis of the impact of each measure on society (externalities). OBJECTIVE: The aim of this paper is to present a case study related to the application of the proposed economic evaluation methodology. METHODS: An analysis of the work accidents in a hospital has been made. Three of the major types of accidents have been selected: needle stings, falls and excessive strain. Following the risk assessment, some preventive measures have been designed. Subsequently, the Benefit/Cost ratio (B/C) of these measures has been calculated, both in financial terms (from the organization's perspective) and in economic terms (including the benefits for the worker and for the Society). RESULTS: While the financial ratio is only advantageous in some cases, when the externalities are taken into account, the B/C ratio increases significantly. CONCLUSIONS: It is important to consider external benefits to make decisions concerning the implementation of preventive measures in Occupational Health and Safety projects.

Postural assessment of school children: an input for the design of furniture.

During the last decades of the previous century, school desks with a tilt top have disappeared. The chairs have been designed for sitting upright, with the hip, knees and ankles all at right angles. However, the erect posture cannot be maintained for more than one or two minutes, after which it will result in fatigue, discomfort or poor posture. The main aim of project is to identify the type of furniture that most effectively contribute to adequate neck and back postures of the school children, by carrying out a postural analysis of a sample of school pupils when using three different types of furniture. The postures adopted by school pupils were monitored by video during several activities, such as reading, writing and painting tasks, copying from a blackboard and listening the teacher. Additionally, the characteristics of the adopted postures were assessed by registering the head tilt, flexion of the neck, trunk and hips position. All these aspects were classified and the results were recorded for future analysis. The obtained results seem to point out that the use of a school desk with a tilted table surface resulted in a reduction in trunk and neck flexion, preserving the natural lordosis in the lumbar and cervical regions. Accordingly, it can be concluded that there are alternatives to consider in the furniture design in order to eliminate tensions and, consequently, to improve children's wellbeing.

Manual materials handling: knowledge and practices among Portuguese health and safety practitioners.

OBJECTIVE: There are several methodologies to assess the risk involved in Manual Materials Handling (MMH). The aim of this study was to identify the knowledge and use of risk assessment methods among Portuguese Health and Safety (H&S) practitioners. PARTICIPANTS: The study involved the participation of 331 H&S practitioners and other related prevention professionals. METHOD: An e-mail invitation to complete an online survey was sent to all Portuguese registered H&S practitioners. The previously developed and validated questionnaire included three different sections: (1) company characteristics; (2) description of types of MMH tasks performed; and (3) the respondents' use of and knowledge about risk assessment methods for MMH tasks. RESULTS: The answers obtained were collected from almost 350 companies. The characteristics of the companies showed that there is a predominance of external and internal H&S services for Small and Medium sized Enterprises (SMEs) and large companies, respectively. The NIOSH equation, Key Indicator Method (KIM) and Manual Assessment Chart (MAC) were identified as the most used and recognised risk assessment methods. CONCLUSION: Questionnaire results show that an important number of Portuguese H&S practitioners recognise some methods but have difficulty applying them correctly. Some practitioners reported that they had never used any type of risk assessment method.

Assessing differences in methodologies for effective noise exposure calculation.

The aim of the present study was to analyse the adequacy of hearing protection devices (HPDs) by applying and comparing different methods for the estimation of effective exposure levels. This comparison involved the attenuation data of 50 HPDs (ear muffs and ear plugs), as well as 11 types of noise spectra and 4 methods. The application of the several methods considered and the comparison of the obtained estimations seem to demonstrate that there are significant differences between effective exposure levels estimated with the different methods analysed.

Individual perception of noise exposure and hearing protection in industry.

Existing approaches that explain the behavior of workers in noisy environments rarely include quantitative variables related to central factors such as noise exposure levels and workers' hearing status. The aim of this study is to analyze the relationship among individual, contextual, and perceptual-cognitive factors and the use of hearing protection devices (HPDs). We studied 516 industrial workers exposed to noise levels greater than the Portuguese action level and developed a conceptual model for HPD use. The multivariate data analysis of the several variables considered revealed that individual risk perception and the outcome value for hearing preservation were the main direct predictors of the use of HPDs. Workers' opinions about the company's safety climate and their perception of noise exposure effects also play important roles as predictors. However, much of the effects of these factors are indirect (i.e., mediated by other variables). Furthermore, these results suggest that risk perception should be considered an essential issue in the design and implementation of any hearing conservation program, particularly in the development of training programs. Actual or potential applications of this research include the definition of more accurate strategies for promoting and motivating the use of HPDs.