Thermal function of a clothing ensemble during work: dependency on inner clothing layer fit

A tight-fitting crewneck undergarment (U) and a loose-fitting shirt (S) were studied as part of a commonly used clothing ensemble (Itot = 0.22 m2 K W-1). Ten clothed male subjects performed standardized packing work (VO2 = 0.761 min-1) at three climatic conditions, 20 degrees C and Va = 0.45 m s-1 (0-30 min), at 5 degrees C and Va = 0.39 m s-1 (30-60 min) and at 5 degrees C and Va = 1.23 m s-1 (76-90 min). From 60-75 min the subjects rested at 20 degrees C. The physiological and subjective responses varied with the environment from slightly warm to cool. U resulted in warmer responses than S: torso and upper arm skin temperatures were higher at both 5 degrees C and 20 degrees C, evaporation rate was higher at 20 degrees C, mean skin temperature was higher during work at 20 degrees C, sweating tended to begin earlier and skin wettedness to be higher with U than with S. No differences were observed in core temperature, heart rates, and subjective thermal evaluations. It was concluded that a tight-fitting inner layer (U) compared to a loose-fitting one (S) allows for less cooling of the skin in both a cool and a slightly warm environment.     

Effects of sock type on foot skin temperature and thermal demand during exercise

Many fabrics and clothing ‘systems’ have been designed to enhance heat balance and provide greater thermal comfort for the wearer. However, studies on the effects of socks have largely been ignored in clothing research. It has been suggested that the thermal state of the extremities may alter core temperature and mental stress may be a major determinant of skin blood perfusion on the foot. However, no definite conclusions have been drawn. The aim of this study was to examine the effects of two different sock types on foot skin temperature and to investigate any impact on whole body thermoregulation and energy expenditure. Sixteen subjects carried out two sessions of treadmill running exercise, one session wearing a standard running sock and one session wearing an ergonomic asymmetric fitted sock. The overall mean heart rate, core (aural) temperature, foot skin temperature, weighted mean skin temperature and sweat rate during exercise were not statistically significant between the sock conditions (p?>?0.05). There was a consistent trend in all participants for the ergonomic sock to induce a higher core temperature and higher skin temperatures compared to the standard sock. Overall mean ratings of perceived exertion and ratings of thermal perception were similar for both sock conditions. Participant questionnaires highlighted a general perception that the ergonomic socks had superior cushioning but that the standard socks were comfortable to wear. Despite there being no significant physiological or thermal differences between socks, the ergonomic sock was perceived to be cooler and was the preferred sock which suggests that subjective perceptions may be more important than objective measurements when selecting a sock for wear during prolonged exercise.     

The impact of activity level on sweat accumulation and thermal comfort using different underwear

Abstract

The purpose of this study was to investigate the significance of work level and sweat production for the total amount accumulated and the location of the sweat in a three-layer ensemble as a function of material and textile construction. Furthermore, it was also an aim to investigate how this influenced thermoregulatory responses and thermal comfort during work and during a rest period. Long-legged/long-sleeved underwear manufactured from two different 100% fibre-type materials, polypropylene and wool, was tested as part of a three-layer clothing system. The underwear manufactured from 100% polypropylene was tested in two different knit constructions, a 1 -by-1 rib knit and a fishnet structure, and the woollen underwear in a 1 -by-1 rib knit construction. The test was performed on eight male subjects (T^a= I0°C, RH = 85%, V^a <0-lm/s), and comprised a twice-repeated bout of 40-min cycle exercise followed by 20 min rest. Each subject conducted two tests with the work level approximating 30% [Vdot]o₂ max and 40% [Vdot]o₂ max, respectively. Skin temperatures, rectal temperature, weight loss and humidity near the skin were recorded during the test. Total changes in body and clothing weight were measured separately. Furthermore, subjective ratings on thermal comfort and on sensation of temperature and humidity were collected. The results demonstrated that high heat and sweat production during work periods, leading to increased sweat accumulation, will give higher thermal discomfort ratings for rest periods as well as for work periods compared to intermittent work with lower work intensities. Distribution of accumulated sweat in the clothing ensemble after heavy sweating is dependent on the fibre type in the underwear. Further, it can be concluded that underwear construction clearly has an influence on the evaporation rate in a three-layer ensemble during work at a high activity level.     

Impact of wet underwear on thermoregulatory responses and thermal comfort in the cold

The purpose of this study was to investigate the significance of wet underwear and to compare any influence of fibre-type material and textile construction of underwear on thermoregulatory responses and thermal comfort of humans during rest in the cold. Long-legged/long-sleeved underwear manufactured from 100% polypropylene in a 1 -by-1 rib knit structure was tested dry and wet as part of a two-layer clothing system. In addition cotton (1-by-l rib knit), wool (1-by-l rib knit), polypropylene (fishnet), and a double-layer material manufactured from 47% wool and 53% polypropylene (interlock knit) was tested wet in the clothing system. In the wet condition 175 g of water was distributed in the underwear prior to the experiment. The test was done on eight men (T_a = 10°C, RH = 85%, V_a < 01 m/s), and comprised a 60min resting period. Skin temperature, rectal temperature, and weight loss were recorded during the test. Total changes in body and clothing weight were measured separately. Furthermore, subjective ratings on thermal comfort and sensation were collected. The tests demonstrated the significant cooling effect of wet underwear on thermoregulatory responses and thermal comfort. Further, the tests showed that textile construction of underwear in a two-layer clothing ensemble has an effect on the evaporation rate from clothing during rest in the cold resulting in a significant difference in mean skin temperature. The thickness of the underwear has more of an influence on the thermoregulatory responses and thermal comfort, than the types of fibres tested.     

Test-retest reliability and concurrent validity of a web-based questionnaire measuring workstation and individual correlates of work postures during computer work

INTRODUCTION: "Ergonomic" questionnaires are widely used in epidemiological field studies to study the association between workstation characteristics, work posture and musculoskeletal disorders among office workers. Findings have been inconsistent regarding the putative adverse effect of work postures. Underestimation of the true association might be present in studies due to misclassification of subjects to risk (i.e. exposed to non-neutral working postures) and no-risk categories (i.e. not exposed to non-neutral working postures) based on questionnaire responses. The objective of this study was to estimate the amount of misclassification resulting from the use of questionnaires. METHODS: Test-retest reliability and concurrent validity of a newly developed questionnaire was assessed. This questionnaire collects data on workstation characteristics and on individual characteristics during computer work (i.e. work postures, movements and habits). Pictures were added where possible to provide visual guidance. The study population consisted of 84 office workers of a research department. They filled out the questionnaire on the Internet twice, with an in-between period of 2 weeks. For a subgroup of workers (n=38), additional on-site observations and multiple manual goniometer measurements were performed. RESULTS: Percentage agreement ranged between 71% and 100% for the test-retest analysis, between 31% and 100% for the comparison between questionnaire and on-site observation, and between 26% and 71% for the comparison between questionnaire and manual goniometer measurements. For 9 out of 12 tested items, the percentage agreement between questionnaire and manual goniometer measurements was below 50%. CONCLUSIONS: The questionnaire collects reliable data on workstation characteristics and some individual characteristics during computer work (i.e. work movements and habits), but does not seem to be useful to collect data on work postures during computer work in epidemiological field studies among office workers.     

Effects of work experience on work methods during dynamic pushing and pulling

Pushing and pulling are potential risk factors for work-related low back disorders (WRLBDs). While several studies have evaluated differences in work methods related to work experience, such evidence for dynamic pushing and pulling is limited. Eight novices and eight experienced workers completed dynamic push/pull tasks using a cart weighted to 250% of individual body mass in two different configurations (preferred vs. elbow handle heights). Multiple measures [hand forces, torso kinematics and kinetics, and required coefficient of friction (RCOF)] were obtained to assess WRLBD and slip risks. Experienced workers generated higher medio-lateral hand forces, during both pulls and pushes, though with a more substantial difference during pushes (∼74%), and which involved the use of hand force components other than to move the cart in an anterior-posterior direction. Experienced workers also had lower peak torso kinematics in flexion/extension and lateral bending, and lower torso flexion/extension kinetics. The latter is suggestive of a lower risk for WRLBDs, though levels of exposures to WRLBD risk were low to moderate in both groups and were often relatively small and inconsistent across the task configurations. Group-level differences in RCOF were quite small, indicating a comparable slip risk between the two groups. Thus, it was considered inconclusive whether the work methods used by experienced workers during dynamic pushing and pulling are advantageous regarding WRLBD and slip risks.     

The daily work load of refuse collectors working with three different collecting methods: a field study

The daily work load of 116 Dutch (male) refuse collectors working with polythene bags, two-wheeled mini-containers and large four-wheeled containers was studied. To this end a time analysis of the tasks and activities in the real working situation was made and the postures and the physiological work load of the collector working with the three different methods was assessed. Manual materials handling and the corresponding working postures were studied by means of observations. Heart rate (HR) was continuously recorded during the working day. Furthermore, to enable the assessment of the work load during refuse collecting as a percentage of the maximal oxygen uptake ([Vdot]O₂max) every refuse collectors' relationship between HR and oxygen uptake was measured during a simulation of the tasks and activities in the laboratory. The range in total working time of the refuse collectors was large. Most time is spent on the task ‘loading’; this lasted on average about 5?h. The mean number of handled objects for the three refuse collecting methods is 1500 bags, 500 mini-containers and 120 large containers respectively. The mean amount of collected refuse per collector of bags and mini-containers is about 11000kg. For the collectors of the large containers it is 27% higher, namely about 14000kg. The mean weight of one object for the bags, mini-container and large container is 7, 22 and 110?kg respectively. The straight posture was the most common in refuse collecting by bags. The posture flexed at the trunk and bent forwards or backwards occurred often while pushing and pulling containers. However, the refuse collectors of the large containers pushed and pulled for shorter periods during a working day in comparison with collectors of the mini-containers. Criteria for energetic overload were set at a mean energy expendiiure of 30% [Vdot]O₂ max and an energy expenditure of 50% [Vdot]O₂ max or more for a maximum of 60?min per day. According to these limits the energetic work load of the collectors of bags was indicated as being too high. In order to formulate guidelines in terms of mechanical and energetic load it is necessary to measure more accurately these loads during refuse collecting activities.     

Combined effects of fabric air permeability and moisture absorption on clothing microclimate and subjective sensation during intermittent exercise at 27 degrees C

The present paper aimed at determining the combined effects of two different levels of air permeability and moisture absorption, in terms of clothing microclimate and subjective sensation, in resting and exercising subjects at an ambient temperature of 27 °C, a relative humidity of 50% and an air velocity of 0.14 m s^-1. Three kinds of clothing ensemble were investigated: (1) polyester clothing with low moisture absorption and low air permeability (A), (2) polyester clothing with low moisture absorption and high air permeability (B), and (3) cotton clothing with high moisture absorption and high air permeability (C). The subjects exercised for 10 min on a cycle ergometer at an intensity of 30% maximal oxygen uptake and then had a 10 min rest. This sequence was repeated four times. The main findings are summarized as follows: (1) The clothing microclimate humidity in the back area was significantly higher in A than in B, and in C than in B. (2) The clothing microclimate temperature in the chest area was significantly higher in B than in A, and in B than in C. (3) The clothing microclimate temperature in the back area was significantly higher in C than in B. (4) The clothing surface temperature was significantly higher in C than in B. (5) Although the positive relationships between the microclimate humidity and forearm sweat rate was significantly confirmed in all three kinds of clothing, the microclimate humidity at chest for the same sweat rate was lower in C than in A and B. (6) Although the positive relationships between subjective sensation and forearm sweat rates were significantly confirmed in all three kinds of clothing, the subjective discomfort seemed to be reduced more effectively in C than in A and B for the same sweat rate. These results were discussed in terms of thermal physiology and combined effects of air permeability and moisture absorbency of the fabrics.     

The effects of a moisture-wicking fabric shirt on the physiological and perceptual responses during acute exercise in the heat

This study investigated the effects that a form fitted, moisture-wicking fabric shirt, promoted to have improved evaporative and ventilation properties, has on the physiological and perceptual responses during exercise in the heat. Ten healthy male participants completed two heat stress tests consisting of 45 min of exercise (50% VO_2peak) in a hot environment (33 °C, 60% RH). One heat stress test was conducted with the participant wearing a 100% cotton short sleeved t-shirt and the other heat stress test was conducted with the participant wearing a short sleeved synthetic shirt (81% polyester and 19% elastane). Rectal temperature was significantly lower (P < 0.05) in the synthetic condition during the last 15 min of exercise. Furthermore, the synthetic polyester shirt retained less sweat (P < 0.05). As exercise duration increases, the ventilation and evaporation properties of the synthetic garment may prove beneficial in the preservation of body temperature during exercise in the heat.     

Strain effects on the band gap and work function of zigzag single-walled carbon nanotubes and graphene: A comparative study

First-principles local density functional calculation of the electronic structure and work function of zigzag single-wall carbon nanotubes (SWCNTs) and graphene under strain are presented. We found that there is a small circumference strain even for unstrained zigzag SWCNTs that release the curvature energy of the tube. Therefore, we propose that there are two effects contributing to the opening of the band gap of unstrained (3q$3q$, 0) SWCNTs: the electron transfer enhancement effect and the circumference strain effect. We show that the band gap and work function of strained zigzag SWCNTs can be successfully estimated from the band structure and work function of strained graphene based on the zone folding method with circumference strain effect. The circumference strain effect is crucial to obtain a correct result. The rate of change of the band gap with respect to the strain for zigzag SWCNTs is almost independent of the value of the strain and the radius of the tube.     

Towards a learning organization: the introduction of a client-centered team-based organization in administrative surveying work

Within administrative surveying work in Sweden, a transition to a client-centered team-based organization was made during 1998. The aim of this study was to describe the employees' perceptions and expectations of job and organizational practices when working as a generalist in a client-centered team-based organization; job and organizational practices and well-being and effectiveness measures were examined when introducing a team-based organization. Interventions such as courses in how to cope with the role of a generalist, how to increase service to clients, education in technology, law and economics, as well as computer information support, were ongoing at the time of the study. The Team Work Profile and QPS Nordic questionnaires were used. All the surveyors in five regions in Sweden participated, in total 640 surveyors. The transition to a client-centered team-based organization was expected to improve job control and job content but at the same time lead to impairments in job climate and group cohesion. Distress was associated with negative future expectations of the organization. High job control and group cohesion were the central contributors towards growth in personal competence and social effectiveness of teamwork. Both internal and external client-related activities of team and organization were in focus during the transition.     

The effects of occupational health and safety management on work environment and health: a prospective study

According to Norway's Internal Control Regulation, all companies are required to have an occupational health and safety (H&S) management system. This study investigated the effects of implementing or improving occupational H&S management on the work environment, H&S-related behaviour and musculoskeletal health of workers in small and medium-sized companies. A one-year prospective cohort study, using self-administered questionnaires, was performed among the managers and blue-collar workers in 226 motor vehicle repair garages. Out of 1559 workers that responded at baseline 721 workers could be identified at follow-up. These 721 workers were included in the study. The workers in companies with improved H&S management from baseline to follow-up reported increased satisfaction with the H&S activities at the garage; improved support from management and colleagues; improved health-related support and control; and increased participation in H&S activities.     

The impact of light and colour on psychological mood: a cross-cultural study of indoor work environments

The aim of the study was to determine whether indoor lighting and colour would have any systematic impact on the mood of people working indoors. Earlier studies have mostly focused either on light, colour or windows in laboratory settings. The present study was carried out in real work environments at different seasons and in countries with different latitudes. A total of 988 persons completed all parts of the study. In the countries situated far north of the equator there was a significant variation in psychological mood over the year that did not occur in the countries closer to the equator. When all four countries were considered together, it became evident that the light and colour of the workplace itself also had an influence on the mood of persons working there. The workers' mood was at its lowest when the lighting was experienced as much too dark. The mood then improved and reached its highest level when the lighting was experienced as just right, but when it became too bright the mood declined again. On the other hand, the illuminance as measured in objective terms, showed no significant impact on mood at any time of the year. The relationship between mood and the distance to the nearest window was bimodal. The results also indicate that the use of good colour design might contribute to a more positive mood. It is suggested that in future research light and colour should be studied as parts of the more complex system making up a healthy building.     

Performance enhancement of hybrid personal cooling clothing in a hot environment: PCM cooling energy management with additional insulation

A novel design of personal cooling clothing incorporating additional insulation sandwiched between phase change materials (PCMs) and clothing outer layer is proposed. Performance of four personal cooling systems including clothing with only PCMs, clothing with PCMs and insulation (PCM?+?INS), clothing with PCMs and ventilation fans (HYB), and clothing with PCMs, ventilation fans and insulation (HYB?+?INS) was investigated. Effect of additional insulation on clothing cooling performance in terms of human physiological and perceptual responses was also examined. Human trials were carried out in a hot environment (i.e. 36?°C, RH = 59%). Results showed that significantly lower mean skin/torso temperatures were registered in HYB?+?INS as compared to HYB. In contrast, no significant effect of the use of insulation on both skin and body temperatures between PCM and PCM?+?INS was observed. Also, no significant difference in thermal sensations, thermal comfort, and skin wetness sensation was registered between cooling systems with and without additional insulation.

Practitioner Summary: Hybrid personal cooling clothing has shown the ability to provide a relatively cool microclimate around the wearer’ body while working in hot environments. The present work addresses the importance of cooling energy saving for PCMs in a hot environment. This work contributes to optimising cooling performance of hybrid personal cooling systems.     

Systems scenarios: a tool for facilitating the socio-technical design of work systems

Abstract

The socio-technical systems approach to design is well documented. Recognising the benefits of this approach, organisations are increasingly trying to work with systems, rather than their component parts. However, few tools attempt to analyse the complexity inherent in such systems, in ways that generate useful, practical outputs. In this paper, we outline the ‘System Scenarios Tool’ (SST), which is a novel, applied methodology that can be used by designers, end-users, consultants or researchers to help design or re-design work systems. The paper introduces the SST using examples of its application, and describes the potential benefits of its use, before reflecting on its limitations. Finally, we discuss potential opportunities for the tool, and describe sets of circumstances in which it might be used.

Practitioner Summary: The paper presents a novel, applied methodological tool, named the ‘Systems Scenarios Tool’. We believe this tool can be used as a point of reference by designers, end-users, consultants or researchers, to help design or re-design work systems. Included in the paper are two worked examples, demonstrating the tool’s application.     

Effect of the number of two-wheeled containers at a gathering point on the energetic workload and work efficiency in refuse collecting

The effect of the number of two-wheeled containers at a gathering point on the energetic workload and the work efficiency in refuse collecting was studied in order to design an optimal gathering point for two-wheeled containers. Three sizes of gathering points were investigated, i.e. with 2, 16 and 32 two-wheeled containers at a gathering point. The collecting of two-wheeled containers was simulated in a test circuit. The energetic workload was quantified by the parameters oxygen uptake (l min⁻¹), heart rate (beats min⁻¹) and perceived exertion. The work efficiency was quantified as the time it took to collect 32 two-wheeled containers per time period. The maximum acceptable amount of two-wheeled containers collected during an 8-h working day was estimated using the energetic criterion of a maximum oxygen uptake of 30% VO_2max. The size of the gathering point had no effect on the oxygen uptake, heart rate or perceived exertion. However, the number of two-wheeled containers per collecting period (work efficiency) and the maximum acceptable amount during an 8-h working day were higher in the conditions with 16 and 32 two-wheeled containers at a gathering point compared to the condition with the 2 two-wheeled containers at a gathering point.     

The impact of organizational ergonomics on work effectiveness: with special reference to concurrent engineering in manufacturing industries

A theoretical interdisciplinary model that gives consideration to the critical human and organizational variables for success in concurrent engineering has been developed and validated based on the data derived from 103 electronic component manufacturing companies in the USA. The aim of the model is to determine the impact of organizational ergonomics on work effectiveness in concurrent engineering. A set of questionnaires was developed and data were collected from the manager of the concurrent engineering effort, the team leader and design, manufacturing and marketing team members. The study supports the proposed model and shows that a reward structure that reflects the team effort and quality of communication are significantly related to concurrent engineering performance. This implies that companies using team work structures should find ways to facilitate effective communication among team members and have a reward structure that is balanced to recognize the success of the team.