Effects of mental workload on manufacturing systems employees: A mediation causal model.

BACKGROUND: Although some research has been done in the Mexican manufacturing industry regarding mental workload, none has explored its association with physical fatigue, body weight gain, and human error simultaneously. OBJECTIVE: This research examines the association between mental workload and physical fatigue, body weight gain, and human error in employees from the Mexican manufacturing systems through a mediation analysis approach. METHODS: A survey named Mental Workload Questionnaire was developed by merging the NASA-TLX with a questionnaire containing the mental workload variables mentioned above. The Mental Workload Questionnaire was applied to 167 participants in 63 manufacturing companies. In addition, the mental workload was used as an independent variable, while physical fatigue and body weight gain were mediator variables, and human error was a dependent variable. Six hypotheses were used to measure the relationships among variables and tested using the ordinary least squares regression algorithm. RESULTS: Findings indicated that mental workload significantly correlates with physical fatigue and human error. Also, the mental workload had a significant total association with human error. The highest direct association with body weight gain was provided by physical fatigue, and body weight gain had an insignificant direct association with human error. Finally, all indirect associations were insignificant. CONCLUSION: Mental workload directly affects human error, which physical fatigue does not; however, it does affect body weight gain. Managers should reduce their employees' mental workload and physical fatigue to avoid further problems associated with their health.

Psychosocial risk factors identification in Mexican workers and RGIII validation.

BACKGROUND: Since 2018, NOM-035-STPS-2018 has been applied in Mexico, focused on measuring psychosocial risk factors (PRFs) in workers and the Reference Guide III (RGIII) has been presented, however, research focused on its validation has been scarce, in very specific sectors and with small samples. OBJECTIVE: Determine the levels of PRFs of five work centers and reliability and validity aspects of RGIII. METHOD: The RGIII was applied to 1458 workers (806 women and 652 men) from five workplace in the industrial sector of Ensenada (Mexico), and the level of risk of the PRFs was analyzed, as well as their reliability and validity through Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA). RESULTS: The PRFs with medium, high and very high-risk levels are Workload, Lack of control over work and Workday. The RGIII presents adequate reliability with Cronbach's α, Alpha ordinal RHO and Omega of 0.93, 0.95 and 0.95, respectively. The EFA shows all five subscales maintain factor loadings greater than 0.43, although Leadership and relationships at work has better saturation values, and Work environment ended with only three items. The CFA indicates Leadership and work relationships with a Root Mean Square Error of Approximation (RMSEA) goodness of fit index of 0.072. CONCLUSION: The RGIII allows the identification and evaluation of the level of risk of PRFs. It complies with sufficient internal consistency. It does not have a clear factorial structure, because it does not meet the minimum values of goodness-of-fit indexes that would allow confirming the structure proposed in RGIII.

Relationship between lean manufacturing tools and their sustainable economic benefits.

Traditionally, the isolated relationship of total preventive maintenance (TPM), quick setup (QS), overall equipment effectiveness (OEE), and one-piece flow (OPF) with economic sustainability (ESU) has been investigated; however, these lean manufacturing (LM) tools are implemented together into production systems, and traditional research does not report their relationships and interactions. To contribute to this gap, this paper integrates all those variables in a structural equation model (SEM), which are related by seven hypotheses that are validated using the partial least squares (PLS) technique using information from 176 responses to a questionnaire applied to the Mexican maquiladora industry. Additionally, a sensitivity analysis has been carried out to determine the probability of occurrence at high and low implementation levels for all variables when they occur in isolation, jointly and conditionally. Findings indicate that TPM is a precursor of QS and OEE, while QS is a precursor of OEE and OPF, OEE is a precursor of OPF and ESU, but also OPF is a precursor of ESU. The sensitivity analysis indicates that low levels of TPM are a risk for reaching adequate levels of OEE and QC, while low levels in OEE and OPF are a risk for reaching adequate ESU levels. Supplementary Information: The online version contains supplementary material available at 10.1007/s00170-022-10208-0.

Temperature Asymmetry Analysis between Left and Right Wrist with Sensory and Infrared Thermography.

This article reports a thermal analysis of the wrists to analyze the behavior and recovery of skin temperature after 20 min when performing a highly repetitive movement, and two thermography methods (sensory and infrared) and research groups were compared. The tests were carried out with 44 participants who performed a repetitive task for 10 min and integrated into two groups, of which 22 were trained workers from a maquiladora company and were analyzed with sensory thermography, and the other 22 were in the laboratory with infrared thermography with undergraduate students. The study area is the left and right hand, specifically the wrists. The proposed hypothesis is that people with some musculoskeletal problems have a decrease in temperature when starting repetitive tasks and thermal asymmetries, which measurements were recorded at 0, 10, 15, and 20 min after the task was finished. Findings indicate that the temperatures in both wrists behave similarly. The workers reached higher temperatures, and the centigrade degrees of asymmetry difference were also higher. The variable with influence on the temperature was fractured in the arm. After thermally analyzing the temperature behavior between the wrists of both hands, it is concluded that there is an increase in temperature after finishing a repetitive task, and it does not stabilize after 20 min. Both thermography methods observed that the asymmetries are greater than 0.5 °C, detecting the possible pathology of carpal tunnel syndrome.

Effect of lean manufacturing tools on sustainability: the case of Mexican maquiladoras.

The Mexican maquiladora industry is applying Lean Manufacturing Tools (LMT) in its production lines; however, few studies have investigated its relationship with sustainability (social, economic, and environmental). This paper presents a second-order structural equation model (SEM) relating 8 LMT integrated into three independent latent variables: continuous improvement (Kaizen and Gemba), supporting tools (Andon, visual management, and Poka-yoke), and machinery and equipment (total productive maintenance, overall equipment effectiveness, and Jidoka) that are related to social, economic, and environmental sustainability as dependent variables. The model is validated with information obtained from 249 companies using partial least squares. Findings show that the application of LMT in the Mexican maquiladora industry avoids the generation of waste and reprocessing. Likewise, the improvement of production processes reduces the waste emitted into the environment and reduces energy consumption. Also, when companies have environmental programs, the work environment is safe, and labor relations are improved, increasing morale and the commitment to work for the company, gaining economic and ecological benefits.

Influence of Resilience on Burnout Syndrome of Faculty Professors.

This research aims to describe the relationship between resilience and burnout facing COVID-19 pandemics. The sample was n = 831 lecturers and professors of a Mexican public university. This study is a quantitative, non-experimental, cross-sectional, explanatory, and ex post facto research using Structural Equations Modeling with latent variables under the partial least square's method technique. We used the CD-RISC-25 and SBI questionnaires to measure resilience and burnout, respectively. Structural Equations Modeling (SEM-PLS) allowed the visualization of the exogenous variable (resilience) in endogenous variables (dimensions of SBI burnout: E9 guilt, E7 emotional exhaustion, E8 indolence, and E6 work illusion). To this day, there are very few previous studies that jointly analyze in Mexico the characteristics of resilience and burnout in the face of the COVID-19 pandemic. Findings show that resources availability has the strongest correlation with accomplishment in teaching, followed by cynicism and emotional exhaustion. These results have important professional implications.

Influence of COVID-19 Pandemic Uncertainty in Negative Emotional States and Resilience as Mediators against Suicide Ideation, Drug Addiction and Alcoholism.

This research uses structural equation modeling to determine the influence of uncertainty due to the COVID-19 pandemic as an independent variable in the negative emotional states and resilience (as mediating variables) vs. drug addiction, alcoholism, and suicide ideation as dependent variables in 5557 students from a public state university in Northern Mexico. The five variables are related through eight hypotheses and tested using partial least squares. We used an adapted questionnaire sent by email in May 2020. Findings show that uncertainty facing the COVID-19 pandemic had a direct and significant influence on negative emotional states and a significant inverse effect on resilience; in the trajectory, drug addiction and alcoholism, and suicide ideation are explained.

Infrared thermal imaging monitoring on hands when performing repetitive tasks: An experimental study.

The monitoring of infrared thermal images is reported to analyze changes in skin temperature in the hand fingers when repetitive work is performed to know which finger has a greater risk of injury, besides, the recovery time is analyzed regarding the initial temperature and its relationship with age, sex, weight, height if practice sports, and Body Mass Index (BMI) per individual. For the above, an experimental test was carried out for 10 minutes on a repetitive operation that takes place in the telecommunications industry and 39 subjects participated in which an infrared thermal image of the dorsal and palmar part of both hands was taken in periods of 5 minutes after the 10-minute test has elapsed. The results show that none of the participants recovered their initial temperature after 10 minutes of the experimental test. In addition, it was found that there is a relationship between skin temperature and sex, and that age influences the recovery of temperature. On the other hand, the thumb, index, and middle fingers have a higher risk of injury in the analyzed task. It is concluded that performing repetitive work with all the fingers of the hand does not show that all they have the same risk of injury, besides that, not all the variables studied affect the recovery of temperature and its behavior.

2-Piece Cork Stoppers as Alternative for Valorization of Thin Cork Planks: Analysis by LCA Methodology.

Natural stoppers are a magnificent closure for the production of aging wines and unique wines, whose application is limited by the availability of raw materials and more specifically of cork sheets of different thickness and quality. The growing demand for quality wine bottle closures leads to the search for alternative stopper production. The two-piece stopper is an alternative since it uses non-usable plates in a conventional way for the production of quality caps. The present study has analyzed the impact of the manufacture of these two-piece stoppers using different methodologies and for different dimensions by developing an LCA (Life Cycle Assessment), concluding that the process phases of the plate, its boiling, and its stabilization, are the phases with the greatest impact. Likewise, it is detected that the impacts in all phases are relatively similar (for one kg of net cork produced), although the volumetric difference between these stoppers represents a significant difference in impacts for each unit produced.

Quantitative Models for Prediction of Cumulative Trauma Disorders Applied to the Maquiladora Industry.

Temperature gradient changes on the surface of the skin or in the middle of the body are signs of a disease. The aim of this study is to develop quantitative models for the prediction of cumulative trauma disorders (CTDs) arising from highly repetitive activities, considering risk factors, such as age, gender, body mass index (BMI), blood pressure (BP), respiratory rate (RR), and heart rate, to prevent injuries in manufacturing factory operators. This research involved 19 individuals from the area of sanding and 14 individuals from the area of tolex in manufacturing factories who had their vital signs and somatometry taken, as well as thermal images of their hands in the dorsal and palmar areas; an evaluation by the OCRA method was also applied. Factors such as BP and heart rate were determined to significantly influence the injuries, but no strong association with BMI was found. Quadratic regression models were developed, the estimates of which were adequately adjusted to the variable (R2 and R2 adjusted > 0.70). When integrating the factors of the OCRA method to the generated models, a better fit was obtained (R2 and adjusted R2 > 0.80). In conclusion, the participants who present levels out of the normal range in at least one of the factors have high probabilities of developing injuries in their wrists.

Burnout Syndrome in Police Officers and Its Relationship with Physical and Leisure Activities.

No previous studies in Mexico have been found that jointly analyze physical and leisure activities as variables related to mental health in police officers. This paper presents research on burnout in Mexican Police officers. The question it answers is: is there any association of burnout with physical and leisure activities and personal profile? A total of 276 police officers (87% men and 13% women) participated. To obtain information, the Spanish Burnout Inventory and the Operational Police Stress questionnaires were used. A cross sectional study design was utilized with tests of validity and reliability, goodness of fit, analysis of variance (ANOVA), and analysis of k-means clusters. Results showed that a high number of policemen had high prevalence of burnout and a high level of mental exhaustion, and that exercise was positively and significantly related to lower burnout risk. Men showed higher risk than women. Results should be considered to improve interventions and occupational health practices in the police force. This paper improves understanding of burnout among policemen and the importance of exercise and leisure activities to alleviate burnout.

Design and validation of a questionnaire in Spanish language for software usability evaluation.

BACKGROUND: Usability is an essential characteristic of software development, which needs to be evaluated mainly through questionnaires. However, the questionnaires available in Spanish are limited and not available for most software's developers and users. OBJECTIVES: This work aimed to design and validate a new questionnaire to evaluate software usability, considering the characteristics of efficiency, effectiveness, and satisfaction as defined by the International Standards Organization. METHODS: The Software Usability Assessment Questionnaire or SUAQ in Spanish language was designed and validated using Kendall's coefficient, Cronbach's Alpha, Factorial Analysis and Scree test. RESULTS: The questionnaire's validation was carried out by five experts through an evaluation of the clarity, coherence, and relevance of the proposed items. Once the questionnaire was administered to 95 participants, an overall reliability value of Cronbach's alpha of 0.839 was obtained. The factorial analysis is viable since a value of 0.757 was found in the Kaiser-Meyer-Olkin (KMO) test, and a significant value was obtained in Bartlett's sphericity test. CONCLUSIONS: The proposed questionnaire proved to be valid and reliable, and therefore, suitable to evaluate software usability in the Spanish language.

Relationship between Burnout and Body Mass Index in Senior and Middle Managers from the Mexican Manufacturing Industry.

This research relates Burnout Syndrome (BS) with the Body Mass Index (BMI) among middle and senior managers of the Mexican manufacturing industry. Even though BS incidence is high in the Mexican industrial population, few systematic studies have explored BS and its relationship with other health problems, such as obesity. The goal of this research is to determine the relationship between BS and the BMI in employees with normal weight, overweight, and obesity. We present three structural equation models to relate BS and the BMI. The BMI ranges were determined according to the parameters (normal weight, overweight, and obesity) proposed by the World Health Organization (WHO). The sample includes 361 employees that voluntarily answered a 31-item questionnaire. We measure the levels of BS using the Maslach Burnout Inventory-General Survey (MBI-GS) and analyze anthropometric and sociodemographic data from the participants. Then, we determine the relationships between the variables through structural equation models and estimate the direct, indirect, and total effects in the three models, which show acceptable reliability. As main findings, the normal weight model has a larger explanatory power than the overweight and obesity models. The same research hypotheses were tested and the effects of BS on the BMI differ across the three models. Such results are presented by taking into account that obesity and overweight require additional factors, such as genetic factors and personal eating habits, to be better explained.

Analysis of burnout syndrome, musculoskeletal complaints, and job content in middle and senior managers: Case study of manufacturing industries in Ciudad Juárez, Mexico.

BACKGROUND: In developing countries such as Mexico, the effects of burnout syndrome (BS) are observed in manufacturing industries. However, the relationships among BS, Job Content (JC), and Musculoskeletal Complaints (MC) are scarcely studied within the manufacturing sector, even though senior and middle managers are exposed to highly demanding and mentally exhausting situations. OBJECTIVES: The objective of this paper is to determine the relationships among the three BS dimensions, MC, and JC among middle and senior managers of the manufacturing industry in Ciudad Juárez, Mexico. METHODS: The Maslach Burnout Inventory-General Survey (MBI-GS), the Job Content Questionnaire (JCQ), and the Body Map assessment were administered as data collection instruments. The sample included 361 participants from six industries located in Ciudad Juárez, Mexico. Also, we proposed structural equations models (SEM) to establish the relationships among variables. RESULTS: The questionnaires and the model showed acceptable reliability and quality indices. Emotional exhaustion was the most relevant latent variable, having significant effects on MC and on professional efficacy, and significantly contributing to increasing levels of cynicism. On the other hand, the variable social support showed a negative direct impact on Job Demands and Emotional Exhaustion. CONCLUSIONS: Actions to reduce emotional exhaustion at work include providing a positive and suitable work environment through social support. These strategies help prevent MC and improve professional efficacy, life quality at work, and productivity.

Structural Model for the Effects of Environmental Elements on the Psychological Characteristics and Performance of the Employees of Manufacturing Systems.

This paper analyzes the effects of environmental elements on the psychological characteristics and performance of employees in manufacturing systems using structural equation modeling. Increasing the comprehension of these effects may help optimize manufacturing systems regarding their employees' psychological characteristics and performance from a macroergonomic perspective. As the method, a new macroergonomic compatibility questionnaire (MCQ) was developed and statistically validated, and 158 respondents at four manufacture companies were considered. Noise, lighting and temperature, humidity and air quality (THAQ) were used as independent variables and psychological characteristics and employees' performance as dependent variables. To propose and test the hypothetical causal model of significant relationships among the variables, a data analysis was deployed. Results found that the macroergonomic compatibility of environmental elements presents significant direct effects on employees' psychological characteristics and either direct or indirect effects on the employees' performance. THAQ had the highest direct and total effects on psychological characteristics. Regarding the direct and total effects on employees' performance, the psychological characteristics presented the highest effects, followed by THAQ conditions. These results may help measure and optimize manufacturing systems' performance by enhancing their macroergonomic compatibility and quality of life at work of the employees.

Ergonomic assessment for the task of repairing computers in a manufacturing company: A case study.

BACKGROUND: Manufacturing industry workers who repair computers may be exposed to ergonomic risk factors. OBJECTIVES: This project analyzes the tasks involved in the computer repair process to (1) find the risk level for musculoskeletal disorders (MSDs) and (2) propose ergonomic interventions to address any ergonomic issues. METHODS: Work procedures and main body postures were video recorded and analyzed using task analysis, the Rapid Entire Body Assessment (REBA) postural method, and biomechanical analysis. RESULTS: High risk for MSDs was found on every subtask using REBA. Although biomechanical analysis found an acceptable mass center displacement during tasks, a hazardous level of compression on the lower back during computer's transportation was detected. CONCLUSIONS: This assessment found ergonomic risks mainly in the trunk, arm/forearm, and legs; the neck and hand/wrist were also compromised. Opportunities for ergonomic analyses and interventions in the design and execution of computer repair tasks are discussed.

Construction of a survey to assess workload and fatigue among AMT operators in Mexico.

UNLABELLED: Operators of machinery classified as Advanced Manufacturing Technology (AMT) are exposed to high levels of workload and fatigue. However, only few studies have been conducted on this topic in Hispanic-American countries workers. Several instruments be used to assess workload and fatigue; however, only few of them have been adapted to Spanish language. This paper reports on the development and validity testing of a survey instrument in Spanish, aiming to subjectively assess workload and fatigue among AMT operators in Mexico. METHOD: After an exhaustive literature review in search of already available measurement instruments, they were adapted for content and later translated into Spanish; a pilot test was conducted to evaluate validity and reliability; afterwards appropriate modifications were made to the testing instruments. Final version of the instrument was applied to a group of 121 operators of CNC lathes. Reliability was analyzed using KMO and Cronbach alpha indices. RESULTS: For the assessment of workload, both NASA-TLX and ISTAS 21 methods were incorporated to the survey instrument. As for fatigue assessment tools, these were SOFI-S, FAS and OFER questionnaires. RESULTS show KMO value and Cronbach alpha above 0.6.Conclusions. The survey instrument as designed, allows the collection of reliable and valid data regarding workload and fatigue among AMT operators in Mexico.