Ergonomics in Practice: Physical Workload and Heat Stress in Thailand

This study consists of assessments of the thermal environment and physio-logical strain in tasks associated with airport, construction, and metal jobs. The number of male and female participants was 108. Environmental heat stress was evaluated with the WBGT index. Physiological strain was evaluated by the relative cardiovascular load (%CVL) based on the measurements of heart rate. Also the increase of body temperature, weight loss, and perceived discomfort were determinated. At work sites the assessments lasted for 2 to 4 hrs for each participant. The mean physiological strain exceeded the level of 30%CVL. Severe peaks (over 60%CVL) were observed in specific tasks being in agreement with perceived discomfort ratings. The increase of body temperature and weight loss in most cases remained within acceptable limits. For the most strenuous tasks, various ergonomic improvements were developed in consultation with workers and managers.     

Psychological and physiological stress reactions of male and female assembly workers: a comparison between two different forms of work organization

Psychological and physiological stress responses of 36 male and 29 female assembly workers were examined during and after work at a car engine factory. Two different ways of organizing assembly work were compared, (1) a more traditional assembly line with fixed work stations organized as a chain and involving short repetitive work cycles and, (2) a new and more flexible work organization with small autonomous groups having greater opportunities to influence the pace and content of their work. Each worker was examined during and after a normal day at work on 2 consecutive days and, in order to obtain endocrine baseline data, during a corresponding work‐free period at home. As expected, both female and male workers in the flexible organization reported significantly more variation, independence and abilities to learn new skills at work. Workers in both forms of work organization showed a significant increase in urinary epinephrine and norepinephrine during work compared to the work‐free day at home. Males had significantly higher epinephrine and systolic blood pressure levels than females. Successive self‐reports of tiredness increased significantly more at the assembly line compared to the flexible work organization. In keeping with this, systolic blood pressure, heart rate and epinephrine increased significantly during the work shift at the assembly line but not during work in the flexible organization. Catecholamine levels revealed that the subjects were able to unwind more rapidly after work in the flexible organization. This pattern was particularly pronounced for the female workers. In summary, the various stress indicators support the notion that the flexible work organization induces less stress than the assembly line and that the female workers were able to benefit most from this new form of work organization. Copyright © 1999 John Wiley & Sons, Ltd.     

Investigating traffic fatality trends and restraint use among rear-seat passengers in the United States, 2000–2016

Introduction: Motor-vehicle crash is one of the leading causes of unintentional injury death in the United States. Previous studies focused on fatalities among drivers and front-seat passengers, with a limited number of studies examining rear-seat passenger fatalities. The objectives of this study were to assess trends in rear-seat passenger motor-vehicle fatalities in the United States from 2000 to 2016 and to identify demographic factors associated with being unrestrained among fatally injured rear-seat passengers. Methods: Rear-seat passenger fatality data were obtained from the Fatality Analysis Reporting System (FARS) database. The fatality rate ratios for overall rear-seat passengers and for different age and sex groups were determined by comparing fatality rates in 2000 and 2016 using random effects models. Risk ratios of being unrestrained for age and sex groups were obtained using general estimating equations. Results: Compared to 2000, the overall rear-seat passenger fatality rate in 2016 decreased by 44% (95% confidence interval [CI]: 39–49%). In particular, the fatality rate among rear-seat passengers decreased more in males than females, and passengers aged 14–19 years experienced a larger decline than all other age groups. Fatally injured male rear-seat passengers had a higher risk of being unrestrained (adjusted risk ratio: 1.06, 95% CI: 1.04–1.07) than their female counterparts, and both youngest (≤13 years) and oldest (65–85 years) passengers were less likely to be unrestrained than those aged 20–64 years. Conclusions: Overall, fatality rates among rear-seat passengers have declined, with differential degrees of improvement by age and sex. Practical Applications: Continued restraint use enforcement campaigns targeted at teenagers and males would further preserve them from fatal injuries and improve traffic safety for the overall population.     

Cardiovascular Strain of Sawmill Workers in South-Western Nigeria

This study aimed to assess cardiovascular strain during sawmilling operations in terms of physical workload, based on heart rate changes. We measured resting and working heart rates and calculated cardiovascular load (%CVL), cardiovascular strain (%CVS) and relative heart rate (%RHR) in 35 sawmill workers. Based on heart rate only, the work in sawmills was classified as very heavy and extremely heavy. Similarly, a high-level category was recorded for %CVL and a very high range for %CVS. Thus, the workload in sawmill operations is usually very high and can lead to physiological strain of the workers. There is a need to redesign the work content of this occupation to prevent excessive strain in the workers, as this will increase their productivity and reduce their health risk.     

A Heart Rate Evaluation Approach to Determine Cost-Effectiveness an Ergonomics Intervention

This paper describes a hear-rate methodology to determine the cost-effectiveness of an ergonomics intervention to reduce workload and improve working conditions. This is a practical approach as opposed to the energy expenditure technique that is difficult to implement in natural settings. This was a laboratory study using a large excavator cabin with devices to simulate excavation operations. Mean heart rate was used to calculate the required rest time during a shift with or without air-conditioning. The criterion for evaluation was differences in required rest time during a shift under these 2 conditions. The simplicity and objectivity of this approach invites use to solve the problem of the economic evaluation of ergonomics interventions.     

2014—2018年铁路辖区职工癌胚抗原检测结果与分析

为了解某铁路辖区职工癌胚抗原异常情况,探讨该人群癌胚抗原异常检测结果的影响因素,以提出防控策略,采用全自动电化学发光仪对2014—2018年铁路辖区职工的癌胚抗原进行测定,共检测159 214份。结果表明,癌胚抗原异常率12.1%,56～60岁人群癌胚抗原异常率最高、为14.5%,男性职工癌胚抗原异常率高于女性,血糖偏高人群癌胚抗原异常率为16.5%。最后提出应进一步重视检测结果,充分利用铁路现有卫生资源,采取健康体检、健康宣传、健康休养、健康管理的防控手段。     

基于生理指标的建筑工人攀登作业疲劳实验研究

为研究攀登作业建筑工人生理疲劳状态的评测指标,提出1种基于生理指标的建筑工人攀登作业疲劳测度实验方法。首先,设计实验测量建筑工人的心率、皮肤温度、舒张压、收缩压4项生理指标,结合Brog’s RPE主观疲劳程度量表研究建筑工人生理疲劳的变化;其次,提取上述4项指标的平均值和标准差作为生理指标特征值,利用静息状态下生理指标特征值和疲劳状态下生理指标特征值进行方差分析、球形检验、T检验筛选出与疲劳相关的特征值;最后,利用支持向量机构建疲劳检测模型。研究结果表明：上述8项生理指标特征值与攀登作业工人疲劳具有显著相关性,疲劳检测模型的准确率为96.875%,研究结果可对攀登作业人员疲劳评估和疲劳预警具有实践性意义。     

Lower Leg Injury Reference Values and Risk Curves from Survival Analysis for Male and Female Dummies: Meta-analysis of Postmortem Human Subject Tests

Objective: Derive lower leg injury risk functions using survival analysis and determine injury reference values (IRV) applicable to human mid-size male and small-size female anthropometries by conducting a meta-analysis of experimental data from different studies under axial impact loading to the foot–ankle–leg complex.

Methods: Specimen-specific dynamic peak force, age, total body mass, and injury data were obtained from tests conducted by applying the external load to the dorsal surface of the foot of postmortem human subject (PMHS) foot–ankle–leg preparations. Calcaneus and/or tibia injuries, alone or in combination and with/without involvement of adjacent articular complexes, were included in the injury group. Injury and noninjury tests were included. Maximum axial loads recorded by a load cell attached to the proximal end of the preparation were used. Data were analyzed by treating force as the primary variable. Age was considered as the covariate. Data were censored based on the number of tests conducted on each specimen and whether it remained intact or sustained injury; that is, right, left, and interval censoring. The best fits from different distributions were based on the Akaike information criterion; mean and plus and minus 95% confidence intervals were obtained; and normalized confidence interval sizes (quality indices) were determined at 5, 10, 25, and 50% risk levels. The normalization was based on the mean curve. Using human-equivalent age as 45 years, data were normalized and risk curves were developed for the 50th and 5th percentile human size of the dummies.

Results: Out of the available 114 tests (76 fracture and 38 no injury) from 5 groups of experiments, survival analysis was carried out using 3 groups consisting of 62 tests (35 fracture and 27 no injury). Peak forces associated with 4 specific risk levels at 25, 45, and 65 years of age are given along with probability curves (mean and plus and minus 95% confidence intervals) for PMHS and normalized data applicable to male and female dummies. Quality indices increased (less tightness-of-fit) with decreasing age and risk level for all age groups and these data are given for all chosen risk levels.

Conclusions: These PMHS-based probability distributions at different ages using information from different groups of researchers constituting the largest body of data can be used as human tolerances to lower leg injury from axial loading. Decreasing quality indices (increasing index value) at lower probabilities suggest the need for additional tests. The anthropometry-specific mid-size male and small-size female mean human risk curves along with plus and minus 95% confidence intervals from survival analysis and associated IRV data can be used as a first step in studies aimed at advancing occupant safety in automotive and other environments.     

有限空间作业人员生理状态监测设备研制

为监测有限空间作业人员异常生理状况,进而保障有限空间作业安全与作业人员生命健康,在分析手腕处6个测量位置信号质量的基础上,获得最佳信号采集位置,并结合事故成因,从光电容积脉搏波(PPG)信号中提取心率、脉搏周期、振幅等生理参数作为评价指标,研制一款针对有限空间特殊作业人群的手腕处脉动生理信息监测设备;并进行系统稳定性测...     

Exploring simulated driving performance among varsity male soccer players

Background: It is documented that male athletes display riskier behaviors while driving (as well as in life in general) than female athletes and nonathletes. However, the literature has reported that athletes show better driving ability than nonathletes. This paradox between behaviors and abilities motivated the present study to further understand the collision risk of varsity athletes.

Objective: The current study estimates the performance differences between varsity male soccer players and male undergraduate nonathletes on (1) a driving task and (2) three perceptual–cognitive tasks (associated with collision risk prediction; i.e., Useful Field of View [UFOV] test).

Methods: Thirty-five male undergraduate students (15 varsity soccer players, 20 undergraduate nonathletes) took part in this study. Driving performance was assessed during 14?min of urban commuting using a driving simulator. While completing the simulated driving task and UFOV test, the physiological responses were monitored using an electrocardiograph (ECG) to document heart rate variability (HRV).

Results: Varsity soccer players showed more risky behaviors at the wheel compared to their nonathlete student peers. Varsity soccer players spent more time over the speed limit, committed more driving errors, and adopted fewer safe and legal behaviors. However, no difference was observed between both groups on driving skill variables (i.e., vehicle control, vehicle mobility, ecodriving). For subtests 1 and 2 of the UFOV (i.e., processing speed, divided attention), both groups performed identically (i.e., 17?ms). The nonathlete group tended to perform better on the selective attention task (i.e., subtest 3 of UFOV test; 63.2?±?6.2?ms vs. 87.2?±?10.7?ms, respectively; this difference was not significant, P = .76).

Conclusion: Preventive driving measures should be enforced in this high-risk population to develop strategies for risk reduction in male team athletes.     

基于驾驶员心率和速度差的高速公路纵坡度研究*

为减少高速公路纵坡路段的事故发生率,利用心生理检测仪采集驾驶员心率数据,使用V-Box采集道路高程和车辆实时速度数据,采用偏相关分析确定影响驾驶员心率增长率和速度差的显著性因素,分别构建驾驶员心率增长率和速度差与坡度之间的关系模型,通过心率增长率阈值和运行速度协调性,从驾驶舒适性角度确定安全坡度范围。研究结果表明:在纵坡路段行车时,驾驶员心率增长率随坡度增大而增加,速度差随坡度增大而增大,坡长与驾驶员心率增长率和速度差呈弱相关;设计车速为100 km/h的高速公路,上坡坡度应小于等于3.7%,下坡坡度应小于等于3.3%,因此建议纵坡坡度小于等于3.3%为宜。研究结果可为高速公路交通安全和人性化设计提供理论依据。     

Flicker Test as a Load Measurement During the Combined Effect of Heat and Noise

This study was a joint physiological and psychological experiment undertaken to determine changes in physiological and psychological human functions under the combined influence of heat, noise, and physical activity. Seven experimental situations were simulated in a climatic chamber with different configurations of three independent variables: heat (40 °C), noise (98 dB), and physical effort (30% of maximum volume of oxygen uptake—V0₂ max). Five psychological variables (critical flicker fusion—CFF, hand tremor, reaction time, subjective climate evaluation, and subjective evaluation of the given condition load) and two physiological variables (heart rate and rectal temperature) were monitored. Results indicate that CFF changed (increased) significantly when more than one experimental variable was applied. These changes coincided with significant changes in both subjective climate evaluation and subjective evaluation of a given condition load. There were no significant changes in psychomotor functions (hand tremor and reaction time). None of the observed physiological parameters were above the critical value. The results suggest that CFF can be treated as a psychophysical load indicator.     

某地区铁路职工高尿酸血症检出情况及影响因素分析

为了解某地区铁路职工高尿酸血症的检出情况及影响因素,以2019年该地区铁路职工21 578名体检人员为研究对象,分析该人群中高尿酸血症的检出情况,研究年龄、性别、体质指数(BMI)、血压、血脂、空腹血糖、尿pH对高尿酸血症的影响.结果表明,高尿酸血症总检出率为22.4％,其中男性检出率(24.4％)高于女性;＜30岁和...     

Occupational noise exposure and hearing defects among sawmill workers in the south of Thailand

The aim of this study was to investigate occupational noise exposure and hearing defects among sawmill workers in the south of Thailand. Seven hundred sawmill workers participated, of which 335 (47.9%) were male. The mean age of the sawmill workers was 33.5 years (SD 10.2), and more than 60% were <35 years old; 75.1% of the workers had less than 5 years of work experience. Only about one in four workers (25%) had been trained in use of personal protective equipment (PPE), and half of the participants never or rarely wore PPE while working. The prevalence rate of noise-induced hearing loss (NIHL) was 22.8% (N?=?42). Male workers had significantly higher risk than female workers (odds ratio [OR]?=?2.21). Workers aged older than 25 years had significantly higher risks for NIHL (OR?=?3.51–12.42) than workers younger than 25 years. Sawing workers had higher risk for NIHL than office workers (OR?=?3.07).     

基于相对心率的体力劳动强度评价方法

体力劳动强度等级的合理划分是劳动者获得合理报酬和身心健康的重要保证。在研究现有体力劳动强度评价方法的基础上,通过实验进行数据的采集并对其进行标准化处理,然后运用回归分析方法建立起以相对心率为解释变量、RPE值为因变量的体力劳动强度评价模型,进行了年龄和环境因素的修正,最后在某企业进行了应用。该模型相对传统体力劳动强度评价方法的改进主要体现在三个方面:第一,指标值测量简单,提高了可操作性;第二,评价等级划分更精确;第三,考虑了年龄和环境因素。该方法在广大工矿企业具有较好的应用价值。     

Effects of carrying handles,postures, materials and distances on carrying capability

This study recruited 14 industrial workers to examine the effects of carrying handles, postures, materials and distances on maximum acceptable weights of carrying (MAWC), and resulting heart rate and body rating of perceived exertion (RPE) for a 20 min intensive carrying task. This study showed that MAWC of carrying with bar handles, carrying with hands-and-body posture, solid materials and 4?m distance were significantly higher than that of carrying with groove handles, carrying with hands posture, liquid materials and 8?m distance, respectively. The resulting heart rates while carrying MAWCs of groove handles, hands-and-body carrying posture, solid materials and 4?m distance were lower than the resulting heart rates while carrying MAWCs of bar handles, hands carrying posture, liquid materials and 8?m distance, respectively. Most pair levels of independent variables resulted in similar body's RPEs except for the pair levels of carrying distance.     

Stress on and off the job as related to sex and occupational status in white-collar workers

Sixty healthy non-smoking white collar employees, aged 30–50, from a large corporation in Sweden participated in the study. There were four groups: 15 male and 15 female middle managers, 15 male and 15 female clerical workers. Each participant was examined individually with regard to cardiovascular and neuroendocrine functions and self-reports for 12 consecutive hours under each of two conditions: (1) a normal day at work (9 a.m.–5 p.m.) and after work (6–9 p.m.), and (2) for the same time period during work-free conditions at home. In addition, everyone was given a videotaped type A-interview and a general health check-up including blood-lipid determination. Attitudes towards work, total workload (including responsibilities outside the paid work) and sex role identity were examined by questionnaires. As expected, all groups showed a moderate increase in cardiovascular and neuroendocrine activity during the day at work. After work, however, interesting group differences emerged, suggesting slower unwinding in female managers. Differences related to occupational level and/ or sex were found for autonomy and social support at work, competitiveness, sex role and reported conflict between demands from paid work and other responsibilities. The stress profile of the female managers was considered in terms of possible long-term health risks.     

Cardiovascular stress, energy expenditure and subjective perceived ratings of fire fighters during typical fire suppression and rescue tasks.

The study determined physiological and psychophysical responses to fire fighters' typical activities. Self-reported assessment of the most demanding fire fighting/rescue tasks were collected with a questionnaire. Then 19 voluntary fire fighters performed 3 simulated fire fighting/rescue tasks in protective clothing. Heart rate (HR), blood pressure and energy expenditure were measured; the rating of perceived exertion (RPE) was assessed with the Borg scale. The questionnaires showed that carrying out victims, fire suppression and resuscitation were classified as heavy load; climbing stairs with a hose as moderate load. According to RPE the subjects considered their effort during ladder climbing fairly light and only somewhat harder during stair climbing and carrying out injured people. The study demonstrated that typical fire fighting/rescue tasks were associated with high energy expenditure and imposed considerable cardiovascular stress. The Borg scale appeared not suitable for assessing perceived exertion in fire fighters during simulated tasks.     

Physiological Method of Evaluating Protective Clothing for Work in a Cold Environment

The purpose of this study was to determine the usefulness of physiological studies in the evaluation of protective clothing for work in a cold environment. The study included the examination of the dynamics of changes in chosen physiological parameters (core and skin temperatures, heart rate, pulmonary minute ventilation) as well as physical ones (the temperature and relative humidity under the clothes) during work in protective clothing with unknown thermal insulation. The experiment was conducted in extreme environmental conditions (–10 and –15°C) at a work load defined by the clothing manufacturer as moderate. Results show that thermal equilibrium was achieved and maintained throughout the investigated work time (60 min) and that the protective clothing ensures safety on the time scale of a regular 8-hour work day. It was also shown that the dynamics of thermal stress physiological parameters can be used to determine the maximum duration of exposure for cold protective clothing with unknown thermal insulation.     

Prediction models for psychophysical lifting capabilities and the resulting physiological responses for work shifts of varied durations

This paper presents models for predicting estimates of maximum weights of lift acceptable to industrial workers for 8-hour work shifts. Prediction models are also presented for heart rate and oxygen uptake at the maximum acceptable weight of lift. Experimental data collected on 37 males and 37 females were used in developing and verifying these models. Each subject performed nine variations of a lifting task involving three heights, four frequencies, and three box sizes to determine estimates of acceptable lifts for 8-hour shifts. The final lifting capability prediction models explained 76 to 82% variance in the experimental data. A procedure is also described to determine, from these models, acceptable lifts for work periods of variable lengths. The physiological-response-prediction models, which provide estimates of heart rate and oxygen uptake at the maximum acceptable weight of lift, were, however, relatively inferior to other similar response models available in the literature. This is thought to be due to the differences between the psychophysical and physiological methodologies.