A dimensional design of tractor seat based on Iranian anthropometric characteristics.

BACKGROUND: The dimensional seat design process should consider both the users' tasks and their physical characteristics. OBJECTIVE: To use an approach for the design and evaluation of seat dimensions based on the anthropometric characteristics of the Iranian population and the requirements of tractor operators. METHODS: Some existing equations relating the seat dimensions to anthropometric characteristics were modified according to logical justifications and international standards. A new mathematical-statistical method was used to extract the equations estimating the constant seat dimensions based on the theoretical maximizing of the accommodation level. In addition, an Overall Seat Accommodation Score (OSAS) was developed to represent the mean of seat dimensions accommodation level and dimensional accommodation equality, simultaneously. RESULTS: The dimensional seat design can be affected under different conditions of adjustability, esthetic, and space limitations. However, it was shown that it is possible to improve the design of tractor seats without any significant increase in the final cost and complexity. CONCLUSION: A new approach was used for tractor seats for a sample of Iranian operators and can be used for the design and evaluation of tractor seats for other target populations.

Psychometric properties of the Iranian version of the wheelchair seating discomfort assessment tool (WcS-DAT) - section II: a revised two-dimensional structure of comfort and discomfort to improve inclusive design practice.

PURPOSE: The objectives of the study were to: 1) validate the Wheelchair Seating Discomfort Assessment Tool (WcS-DAT - section II) in Iran, and 2) to determine whether or not the items on the scale address just one dimension (e.g., discomfort). METHODS: A descriptive-methodological study was performed among 109 (76 males and 33 females) full-time wheelchair users, aged 12-70 years in Tabriz, Iran. To develop the revised Iranian version of the WcS-DAT - section II, a standard "forward-backward" method was in the first step. Then, the content validity and construct validity of the tool was assessed based on feedback from an expert panel and factor analyses (exploratory and confirmatory), respectively. Sensitivity (using ceiling/floor effect), internal consistency (using Cronbach's α), and test-retest reliability (using Intraclass Correlation Coefficient - ICC) were also evaluated. RESULTS: Results established content validity, sensitivity, internal consistency (values of Cornbrash's α: 0.79-0.82), and test-retest reliability (values of ICC: 0.79-0.93) of the Iranian WcS-DAT - section II. Factor analyses revealed a two-factor structure (comfort and discomfort), for the scale, and thus confirmed its construct validity. CONCLUSIONS: The findings suggest that the Iranian version of WcS-DAT- section II is a reliable and valid tool for the evaluation of wheelchair seating comfort and discomfort in the Iranian population. The revised two-factor model of comfort/discomfort has potential implications for inclusive design research and practice.

The revised Iranian version of the Wheelchair Seating Discomfort Assessment Tool (WcS-DAT) is a valid tool to assess individual and wheelchair fit in the context of daily activities performed.A two-factor model of the instrument measuring wheelchair seating comfort and discomfort provides a more detailed understanding of the two constructs (e.g., comfort and discomfort), which is especially important in ergonomic evaluations and interventions.Additional attention to the specific needs of wheelchair using populations has a potential to improve the universal design of future products.

Methodological considerations in the study of perceived discrimination at work: a scoping review protocol. / Consideraciones metodológicas en el estudio de la discriminación laboral percibida: protocolo de una revisión panorámica.

Introduction: Perceived discrimination is a complex phenomenon of study and has significant repercussions on people's health. Many studies confirm the negative effects of stress on workers' health in the workplace, affecting both their physical and mental health. However, there is no consensus when investigating the construct of "perceived work discrimination". Objective: To examine how perceived workplace discrimination has been investigated, considering its association with health and occupational outcomes. Methods: A scoping review will be performed according to the PRISMA guidelines for scoping reviews and the Joanna Briggs Institute. We will search for published articles in english and spanish between 2000 and 2022 in the Scopus, MEDLINE/PubMed, and PsycInfo databases. Through the Rayyan application, two reviewers will independently select titles and abstracts. Then, they will review the full texts. Subsequently, relevant information about the selected articles will be extracted, and their methodological quality will be evaluated. Finally, a narrative synthesis of the main results found will be made. Discussion: We expect the findings to improve methodological aspects when investigating perceived workplace discrimination, facilitating decision-making for those researchers who wish to address perceived work discrimination.

Introducción: La discriminación percibida es un fenómeno complejo de estudiar y que tiene grandes repercusiones en la salud de las personas. En el ámbito laboral, existe un gran número de estudios que confirma los efectos negativos en la salud de los trabajadores, afectando la salud física y psicológica de estos. Sin embargo, no existe un consenso al momento de investigar el constructo "discriminación laboral percibida". Objetivo: Explorar como se ha investigado la discriminación laboral percibida, considerando su asociación con salud y resultados ocupacionales. Métodos: Se realizará una revisión panorámica de acuerdo con las guías PRISMA para revisiones panorámicas y del Instituto Joanna Briggs. Se efectuará la búsqueda de los artículos publicados en idioma inglés y español entre los años 2000 y 2022 en las bases de datos Scopus, MEDLINE/PubMed y PsycInfo. A través de la aplicación Rayyan, dos revisores realizarán de manera independiente la selección de títulos y resúmenes. Luego, los mismos revisarán los textos completos. Posteriormente, se extraerá la información relevante sobre los artículos seleccionados y se evaluará la calidad metodológica de estos. Finalmente, se hará una síntesis narrativa de los principales resultados encontrados. Discusión: Se espera que los hallazgos contribuyan a mejorar los aspectos metodológicos al momento de investigar la discriminación laboral percibida y facilitar la toma de decisiones de aquellos investigadores que deseen abordar la discriminación laboral percibida.

Consideraciones metodológicas en el estudio de la discriminación laboral percibida: protocolo de una revisión panorámica / Methodological considerations in the study of perceived discrimination at work: a scoping review protocol

Introducción La discriminación percibida es un fenómeno complejo de estudiar y que tiene grandes repercusiones en la salud de las personas. En el ámbito laboral, existe un gran número de estudios que confirma los efectos negativos en la salud de los trabajadores, afectando la salud física y psicológica de estos. Sin embargo, no existe un consenso al momento de investigar el constructo "discriminación laboral percibida". Objetivo Explorar como se ha investigado la discriminación laboral percibida, considerando su asociación con salud y resultados ocupacionales. Métodos Se realizará una revisión panorámica de acuerdo con las guías PRISMA para revisiones panorámicas y del Instituto Joanna Briggs. Se efectuará la búsqueda de los artículos publicados en idioma inglés y español entre los años 2000 y 2022 en las bases de datos Scopus, MEDLINE/PubMed y PsycInfo. A través de la aplicación Rayyan, dos revisores realizarán de manera independiente la selección de títulos y resúmenes. Luego, los mismos revisarán los textos completos. Posteriormente, se extraerá la información relevante sobre los artículos seleccionados y se evaluará la calidad metodológica de estos. Finalmente, se hará una síntesis narrativa de los principales resultados encontrados. Discusión Se espera que los hallazgos contribuyan a mejorar los aspectos metodológicos al momento de investigar la discriminación laboral percibida y facilitar la toma de decisiones de aquellos investigadores que deseen abordar la discriminación laboral percibida.

Introduction Perceived discrimination is a complex phenomenon of study and has significant repercussions on people's health. Many studies confirm the negative effects of stress on workers' health in the workplace, affecting both their physical and mental health. However, there is no consensus when investigating the construct of "perceived work discrimination". Objective To examine how perceived workplace discrimination has been investigated, considering its association with health and occupational outcomes. Methods A scoping review will be performed according to the PRISMA guidelines for scoping reviews and the Joanna Briggs Institute. We will search for published articles in english and spanish between 2000 and 2022 in the Scopus, MEDLINE/PubMed, and PsycInfo databases. Through the Rayyan application, two reviewers will independently select titles and abstracts. Then, they will review the full texts. Subsequently, relevant information about the selected articles will be extracted, and their methodological quality will be evaluated. Finally, a narrative synthesis of the main results found will be made. Discussion We expect the findings to improve methodological aspects when investigating perceived workplace discrimination, facilitating decision-making for those researchers who wish to address perceived work discrimination.

Head and facial dimensions of Chilean workers for design purposes and the differences with other populations.

BACKGROUND: An appropriate match between a product and its end-users requires anthropometric data, which show variations among different countries. Proper Personal Protection Equipment (PPE) fit is key for safety and comfort. Chile had no head and facial anthropometric data available in order to design face/head PPE. OBJECTIVE: To describe face/head anthropometric characteristics of Chilean workers. Additionally, this study compared those dimensions against other populations (United States (US), South Korea and China). METHODS: An anthropometric survey involving 21 measures was conducted between September 2013 to May 2016 using stratified sampling. The measurements were based on ISO/TS 16976-2 and ISO 15535 to ensure the highest standards possible, and a total of 474 workers, aged from 18 to 66 years old, participated in the survey. RESULTS: The biggest differences were in Neck circumference, Weight, Nose breadth, Nose protrusion, Bitragion chin arc, Face length, Subnasale-sellion length, Face width, Bigonial breadth and Bitragion subnasal arc. Head length of Chileans were longer than Chinese and South Korean ones, but shorter than US Head length. Chilean Head breadth is smaller than Chinese and South Korean ones. Chileans Face length was the largest observed. Face width of Chileans was smaller than US and Chinese ones. Gender specific differences were also observed in the inter-country comparisons. Chilean males had larger anthropometric dimensions than females. CONCLUSION: Chilean Head and face dimensions differed significantly when compared against US, South Korean and Chines Head and Face dimensions. Chileans have longer and narrower faces with wider mouths, with a head size in between the US and Asian heads. Face and head PPE for Chileans should use dimensions in the current paper in order to ensure proper fit.

Developing countries and the use of ISO Standard 11228-3 for risk management of Work-Related Musculoskeletal Disorders of the Upper Limbs (WRMSDs-ULs): The case of Chile.

Work-Related Musculoskeletal Disorders of the Upper Limbs (WRMSDs-ULs) are one of the most common occupational diseases worldwide. Repetitive motion is one of the main risk factors associated with these conditions. Several efforts have been made within the scientific community in order to develop specific methods to assess the risk that repetitive work represents. Furthermore, internationally coordinated work has resulted in the generation of a series of ISO standards to address issues around ergonomics in the workplace. In 2012, Chile adopted the ISO11228-3 standard checklist in its regulatory process, creating the first technical standard of risk management for repetitive motion. The aim of this study is to present the results of a nation-wide online survey of Chilean Health and Safety Practitioners and Ergonomists, which was conducted in order to identify their level of application experience, most commonly adopted practices, and opinions on the first Chilean Standard for WRMSDs-ULs risk assessment. A second aim is to discuss common issues and possible improvements in public policies, and the adoption of international instruments by developing countries. A total of 331 respondents completed the survey (183 Ergonomists and 148 non-ergonomist). It was observed that a number of the participants consider that the adaptation of the ISO standard has several issues, ranging from simple ones as wording and format to more complex ones regarding overall structure, logic, and ease of use. One of the main issues expressed is the fact that during the adaptation process the instrument is applied in multitask jobs, without providing clear instructions or training. Furthermore, among the top three most used assessment methods were RULA and REBA, which are posture-driven, instead of methods validated for repetitive motion. The issues detected by the Chilean OHS practitioners are common in developing countries, where an intersection of lack of resources, public agency authoritarianism, and poor communication between public-private and public-public organizations contribute to poor consultation, validation, and adaptation processes. Suggestions to improve the current Chilean standard, as well as considerations for developing countries, are presented.

Perception of just culture and its association with work-related psychosocial factors in an Iranian industrial setting: Implications for prevention of errors.

BACKGROUND: A just culture is one in which the reporting of errors and near misses is supported without fear of retribution. The relationship of just culture and psychosocial factors at work has not been explored sufficiently in the literature. OBJECTIVE: To investigate the perception of just culture and its association with socio-demographic and work-related psychosocial factors among 302 employees in an industrial setting in Iran. METHODS: Just culture was assessed using the Just Culture Assessment Tool, and the Copenhagen Psychosocial Questionnaire was used for evaluation of psychosocial work factors (including influence at work, meaning of work, commitment to the workplace, predictability, rewards, quality of leadership, social support from supervisors, trust, and justice and respect). Data were analysed using t test, analysis of variance (ANOVA), and general linear regression analysis. RESULTS: The results indicated that the employees had a fairly positive view on their organisation's just culture, though there were some areas such as trust and balance that needed further attention. The psychosocial issues (particularly commitment to the workplace, meaning of work, social support from supervisors, and rewards) were not adequate from the employees' perspective. Predictability, rewards, and quality of leadership, were the significant psychosocial predictors of just culture in a multivariate regression model. CONCLUSIONS: The findings highlight the areas that need to be considered to improve the experience of organisational just culture, which is important from the point of view of prevention of safety errors and incidents.

Mismatch between jar opening demands and wrist torque strength of consumers in Iran.

This study evaluated the potential mismatch between vacuum-sealed jar opening demands and wrist torque strength of 758 (384 males and 374 females) participants aged 5-74 years in Iran. Wrist ulnar/radial (U/R) torque strength of participants and required torque for opening the existing jars (with 2 different sizes - 65 mm and 85 mm diameter lids) were measured using a digital angle torque adaptor and then compared together to identify any potential mismatch between them. The mismatch percentages were defined as the number of participants whose maximal wrist U/R torque strength were lower than the minimum required torque strength for opening the vacuum-sealed jars. Minimum required torque strength for opening the existing 65 mm and 85 mm vacuum-sealed jars were 4.1 Nm and 6.6 Nm, respectively (range = 4.1 Nm to 10.2 Nm). A considerable mismatch (range = 25%-100%) was found between the required torque strength for opening the existing jars and the wrist U/R torque strength of the study population, particularly for females and those aged 5-9 years. A torque limit of 1.8 Nm was proposed for opening jars for the entire population.

Application of mismatch equations in dynamic seating designs.

Anthropometry is critical for product and workplace design. Highly prevalent, office work is associated with sedentarism and physical discomfort due to prolonged sitting. Dynamic seating (alternating across sitting, perching, and standing) has been suggested as an alternative to overcome those problems. The current study tested a large sample of anthropometric data for mismatch levels against national and international office furniture standards using dynamic seating as a framework with traditional and perching mismatch equations, applied to three recommended dynamic seating components. Dimensions present in the standards used did not match the majority of the sample. For sitting, seat width and depth individually presented the lowest levels of match, as well as under cumulative fit of all office furniture dimensions. However, these were alleviated when incorporating adjustability. Perching was shown to be generally impeded given commercially-available chair height options. Limitations in state-of-the-art perching equations are discussed, and two new models are proposed as design alternatives. Further research should focus on testing the criteria presented in this research through discomfort and objective measures.

Educational level and its relationship with body height and popliteal height in Chilean male workers.

A secular trend in body height has been experienced in many nations and populations, hypothesized to be the result of better living conditions. Educational level has been shown to be closely associated with body height. This study examined the changes in body height and popliteal height in a group of adult Chilean male workers by age cohort and the relationship of these with educational level. The body heights and popliteal heights of 1404 male workers from the Valparaíso and Metropolitan regions of Chile were measured in 2016. The sample was grouped by level of education (primary, secondary, technical and university) and age (21-30, 31-40 and 41-50 years). Robust ANOVA and post-hoc analyses using a one-step modified M-estimation of location were conducted based on bootstrap resampling. Both body height and popliteal height increased from the older to the younger age cohort. The largest increase was from the 41-50 to the 21-30 group, with a 1.1% increase in body height and 1.7% increase in popliteal height. When educational level was introduced into the analysis there was a marked increase in both body height and popliteal height for each cohort, but only in primary- and secondary-educated workers. Despite showing an overall increase in body height and popliteal height, younger workers with the highest levels of education showed fewer differences between them than did older workers with less education. The differences were larger in the older than in the younger cohorts. Similarly, this trend was less clear in workers with higher levels of education (technical and university), probably because of a dilution effect caused by increased access to higher education by workers in the lower income quintiles.

Effect of a posture correction-based intervention on musculoskeletal symptoms and fatigue among control room operators.

This study was conducted to examine the effect of a posture correction-based intervention (with a biofeedback device) on the occurrence of musculoskeletal symptoms (MSS) and fatigue among control room operators in a petrochemical plant in Iran. A total of 188 office workers (91 in the case group and 97 in the control group) participated at baseline as well as at 6- and 12-month follow-up. A questionnaire survey (including the Nordic Musculoskeletal Questionnaire and Multidimensional Fatigue Inventory) and direct observations of working postures by using the Rapid Upper Limb Assessment (RULA) method were used. The occurrence of MSS in the shoulders, upper back, neck, and low back areas, as well as the mental and physical dimensions of fatigue were found to be the most common problems. The results showed considerable improvements in working postures (in the neck, trunk, and RULA grand scores) and the occurrence of MSS (particularly in the neck, shoulders, and upper back and low back areas) and fatigue (in particular the mental and physical aspects) after the intervention. The overall mean RULA grand score for the case group was significantly decreased after the intervention (mean scores of 5.1, 4.4, and 4.6 at pre-intervention, post-intervention 1, and post-intervention 2, respectively). A total of 81 operators (89.0%) reported some kind of MSS at baseline, which were reduced to 75 operators (82.4%) and 77 operators (84.6%) at post-interventions 1 and 2, respectively. Significant differences were also found between the pre- and post-intervention scores for the physical fatigue (mean of 12.19, 10.16, and 9.99 at pre-intervention, post-intervention 1, and post-intervention 2, respectively) and mental fatigue (mean of 14.03, 12.05, and 12.16 at pre-intervention, post-intervention 1, and post-intervention 2, respectively) dimensions. The findings confirm the effectiveness of this low-cost, simple, and easy-to-use ergonomic intervention.

A review of the methodology and applications of anthropometry in ergonomics and product design.

Anthropometry is a key element of ergonomic studies for addressing the problem of fitting the tasks/products to user characteristics, but there is a gap between anthropometric data and their application for designing ergonomic products and environments. This research was conducted to review the literature on the methodology and applications of anthropometry for the ergonomic design of products and environments, and to identify where further research is needed to improve its application and evaluation protocols. One hundred and sixteen papers meeting the inclusion criteria were reviewed. Although a number of anthropometric investigations have been conducted to improve the design of products/environments for different users, further research seems to be necessary, particularly for special groups, such as children, the elderly and people with disabilities. Different anthropometric measurement methods/techniques and fitting criteria are discussed regarding their applicability for various design applications. This review also highlights methodological issues (sampling considerations and prototype evaluation and testing) that should be considered in future research to ensure a user-centred approach of the design process. Practitioner Summary: A literature review was conducted on the methodology and applications of anthropometry for the ergonomic design of products/environments. This review emphasises the need for anthropometric research to design for special groups, such as children, the elderly and people with disabilities, and methodological issues that should be considered in future research. Abbreviations: 1D: one-dimensional; 2D: two-dimensional; 3D: three-dimensional; HF/E: Human Factors/Ergonomics; PCA: Principal Components Analysis; CA: Cluster Analysis; DHM: Digital Human Modelling.