A novel approach for fit analysis of thermal protective clothing using three-dimensional body scanning

The garment fit played an important role in protective performance, comfort and mobility. The purpose of this study is to quantify the air gap to quantitatively characterize a three-dimensional (3-D) garment fit using a 3-D body scanning technique. A method for processing of scanned data was developed to investigate the air gap size and distribution between the clothing and human body. The mesh model formed from nude and clothed body was aligned, superimposed and sectioned using Rapidform software. The air gap size and distribution over the body surface were analyzed. The total air volume was also calculated. The effects of fabric properties and garment size on air gap distribution were explored. The results indicated that average air gap of the fit clothing was around 25–30 mm and the overall air gap distribution was similar. The air gap was unevenly distributed over the body and it was strongly associated with the body parts, fabric properties and garment size. The research will help understand the overall clothing fit and its association with protection, thermal and movement comfort, and provide guidelines for clothing engineers to improve thermal performance and reduce physiological burden.     

Application of thermoregulatory modeling to predict core and skin temperatures in firefighters

The purpose of the study was to compare body temperature responses from subjects who exercised while wearing firefighter clothing to predictive data from a real-time thermoregulatory model that had been initially developed and validated for use in the military. Data from two firefighter studies, firefighter study 1 (FFS1: 7 males and 3 females, continuous treadmill exercise at 50% VO_2max, 25 °C, 50% RH) and firefighter study 2 (FFS2: 6 males, intermittent treadmill exercise at 75% VO_2max, 35 °C, 50% RH), were utilized for the thermoregulatory modeling and comparison. The results showed that prediction error (RMSD) of the model for core and skin temperatures was 0.33 and 0.65 °C in FFS1 and 0.39 and 0.86 °C in FFS2, respectively. While the real-time thermoregulatory model tested in the present study showed the potential for providing a means for reasonably accurate prediction of body temperature responses in firefighters, further development on the model's metabolism algorithms to include adjustments for protective clothing, options to facilitate external work, inclusions of cooling effects are suggested.Relevance to industryFirefighters exposed to thermal extremes experience physiological strain, but direct monitoring of physiological variables is not always practical. Thermoregulatory models can simulate the thermal responses reasonably accurately by applying known thermo-physiological mechanisms together with heat loss mechanisms related to clothing and environment in an effort to improve firefighter safety.     

Subjective perceptions and ergonomics evaluation of a liquid cooled garment worn under protective ensemble during an intermittent treadmill exercise

While a personal protective equipment (PPE) ensemble effectively provides workers with protection from occupational hazards, working in a vapour-resistant ensemble increases the risk of heat illness/injuries and physiological burdens. The purpose of this study was to investigate the effect of body cooling via a liquid-cooled garment (LCG) underneath a PPE ensemble on perceived thermal strain, physiological responses and ergonomics during an intermittent treadmill exercise in warm environmental conditions. The results of the present study indicated that the concomitant wearing of LCG underneath the PPE ensemble significantly reduced subjective perception of heat and alleviated overall increase in body temperature and heart rate while no impact of wearing LCG on ergonomic features was found. The extension of the present findings to practical applications in occupational settings requires further research on a LCG system design and performance evaluations while the LCG is incorporated within the PPE ensemble.

Statement of Relevance: Implementation of a LCG underneath PPE for body cooling was investigated, focusing on its impact on individuals' perceived thermal strain, physiological responses and ergonomics. The findings of the present study indicated that body cooling via a wearable LCG underneath PPE significantly alleviated both perceived thermal and physiological strain in uncompensable heat stress condition.     

Effects of two kinds of clothing made from hydrophobic and hydrophilic fabrics on local sweating rates at an ambient temperature of 37°C

Abstract

The purpose of this study was to find the effects of clothing made from hydrophobic and hydrophilic fabrics on the sweating physiology in environmental conditions where only the mechanisms of wet heat loss could occur. A comparison was made of the local sweat rates from the forearm and their related physiological parameters between polyester (E) and cotton (C) clothing at an ambient temperature (T _a) of 37°C. Six female students, aged from 21 to 28 years, served as subjects. The subjects wore clothing made from either fabric E or fabric C and rested quietly for 60 min in a chair mounted on the bed scale under the influences of environmental conditions of 37°C and 60% relative humidity (rh) with an air velocity of 0 1 m-s^-l.

The major findings are summarized as follows: (1) Local sweat rates were distinctly higher in E than in C in five out of six female subjects. (2) Clothing surface temperatures at the chest level were significantly higher in C than in E. (3) The positive relationship between local sweat rates and mean skin temperature (Tsk) existed both in E and in C. However, the local sweat rates were mostly higher in E under the influences of the same T _sk. These results are discussed in terms of thermal physiology and clothing sciences. It was concluded that the different properties of moisture absorbency between E and C could play a role for sweating physiology in the environmental conditions where only the mechanism of wet heat loss could occur.     

The development of anti-heat stress clothing for construction workers in hot and humid weather

The purpose of this study was to develop anti-heat stress clothing for construction workers in hot and humid weather. Following DeJonge’s functional clothing design process, the design situation was explored, including clothing fabric heat/moisture transporting properties and UV protection and the aspects of clothing ergonomic design (mobility, convenience, and safety). The problem structure was derived from the results of the surveys in three local construction sites, which agreed well with the task requirements and observations. Specifications were consequently described and 30 commercially available fabrics were identified and tested. Fabric testing data and design considerations were inputted in S-smart system to predict the thermal functional performance of the clothing. A new uniform prototype was developed and evaluated. The results of all measurements suggest that the new uniform which incorporated fabrics with superior heat/moisture transporting properties and loose-fitting design could reduce the workers’ heat stress and improve their comfort and work performance.

Practitioner Summary:

The construction workers’ uniform currently used in Hong Kong during summer was unsatisfactory. Following DeJonge’s functional clothing design process, an anti-heat stress uniform was developed by testing 30 fabrics and predicting clothing thermal functional performance using S-smart system. The new uniform could reduce the workers’ heat stress and improve their comfort and work performance.     

Cardiovascular and thermal consequences of protective clothing: a comparison of clothed and unclothed states

We have undertaken a laboratory-based examination of the cardiovascular and thermal impact of wearing thermal (heat) protective clothing during fatiguing exercise in the heat. Seven males completed semi-recumbent, intermittent cycling (39.6 degrees C, 45% relative humidity) wearing either protective clothing or shorts (control). Mean core and skin temperatures, cardiac frequency (f(c)), stroke volume (Q), cardiac output (Q), arterial pressure, forearm blood flow (Q(f)), plasma volume change, and sweat rates were measured. In the clothed trials, subjects experienced significantly shorter times to fatigue (52.5 vs. 58.9 min), at lower peak work rates (204.3 vs. 277.4 W), and with higher core (37.9 degrees vs. 37.5 degrees C) and mean skin temperatures (37.3 degrees vs. 36.9 degrees C). There was a significant interaction between time and clothing on f(c), such that, over time, the clothing effect became more powerful. Clothing had a significant main affect on Q, but not Q, indicating the higher Q was chronotropically driven. Despite a greater sweat loss when clothed (923.0 vs. 547.1 g.m(-2) x h(-1); P<0.05), Q(f) and plasma volume change remained equivalent. Protective clothing reduced exercise tolerance, but did not affect overall cardiovascular function, at the point of volitional fatigue. It was concluded that, during moderately heavy, semi-recumbent exercise under hot, dry conditions, the strain on the unclothed body was already high, such that the additional stress imparted by the clothing ensemble represented a negligible, further impact upon cardiovascular stability.     

Scan posture definition and hip girth measurement: the impact on clothing design and body scanning

Abstract

Ergonomic measurement is central to product design and development; especially for body worn products and clothing. However, there is a large variation in measurement definitions, complicated by new body scanning technology that captures measurements in a posture different to traditional manual methods. Investigations of hip measurement definitions in current clothing measurement practices supports analysis of the effect of scan posture and hip measurement definition on the circumferences of the hip. Here, the hip girth is a key clothing measurement that is not defined in current body scanning measurement standards. Sixty-four participants were scanned in the standard scan posture of a [TC]² body scanner, and also in a natural posture similar to that of traditional manual measurement collection. Results indicate that scan posture affects hip girth circumferences, and that some current clothing measurement practices may not define the largest lower body circumference. Recommendations are made concerning how the hip is defined in measurement practice and within body scanning for clothing product development.

Practitioner Summary: The hip girth is an important measurement in garment design, yet its measurement protocol is not currently defined. We demonstrate that body posture during body scanning affects hip circumferences, and that current clothing measurement practices may not define the largest lower body circumference. This paper also provides future measurement practice recommendations.     

Net Radiation and Heat Transfer through Clothing: The Effects of Insulation and Colour

Abstract

Measurements are reported of the influence of net radiative energy fluxes on the sensible heat flux transmitted through clothing. Measurements with heat flow discs illustrate the effects of clothing colour and reflectance on the sensible heat load. For the same incident short-wave radiant load the difference between the energy flux passing lo the skin through black and through white shirts was 190 W m^-2 when the net radiation to the black shirt was 780 Wm^-2. The results are consistent with simple linear models of heat transfer through clothing assemblies.     

Conditioned clothing: the needs of industry and the wearer

Abstract

Conditioned clothing for alleviating the effects of heat and cold has found use mainly in military applications. There are a few circumstances in industry where the provision of such clothing could be an economic proposition. Very often, however, there are other factors that militate against its adoption, e.g. the need for protection against hazards other than heat and cold, problems of wearer acceptance and interference with the work. Clearly the solution of these problems requires close co-operation between industry and clothing manufacturers as has been achieved in the nuclear industry.     

Why do thin stockings keep legs so warm?

Abstract

The insulation conferred by a thin stocking is trivial compared with other insulation normally present between skin and environment. It is suggested that stockings keep legs warm by reducing the sudden cooling which occurs when cold clothing comes in contact with the limb, to which the cold receptors in the skin are particularly sensitive. If this explanation is correct, wearing stockings will probably increase body heat loss.     

The ergonomics of ventilated operating theatre clothing

Abstract

The results of a recent Department of Health and Social Security/Medical Research Council (DHSS/MRC) trial into the use of ultra-clean ventilation systems shows that these can bring about a reduction in the rate of wound sepsis in orthopaedic operations, particularly when body exhaust ventilated clothing is worn by members of the surgical team.

Although considerable information exists about the reduction of bacteria shedding from individuals wearing body exhaust gowns, little information is available about wearer comfort and related problems. This study was carried out to examine the ergonomic consequences for operating theatre staff of wearing ventilated clothing and to compare these with the results for other forms of specialized surgical garments.

The investigation consisted of observations of theatre staff at work, interviews and an experimental simulation of the orthopaedic surgeon's task.

The results showed that there were measurable differences in skin temperature and sweat rate between ventilated and non-ventilated gowns. Subjectively there was a significant preference for certain garments based on general comfort and thermal perceptions. It was concluded that the ’Mandarin’ body exhaust ventilated gown gave high levels of both objectively and subjectively assessed thermal comfort for the wearer. Where there were operational difficulties or objections to using a ventilated gown, it was concluded that a gown made from ’Gore-tex’ was a possible alternative. It is important that the ergonomic and comfort aspects of these gowns should be related to the attenuation in bacterial shedding that they produce.     

Design Methods for Nuclear Power Plant System Design

This paper examines the physiological response of a group of four volunteers working for 120?min in a warm environment, DB/WB 34/25-5°C, whilst wearing each of two clothing assemblies, KD and OG, with and without the UK NBC S6 respirator. The men were given 10 days training and heat acclimation prior to commencing the tests.

The clothing assembly OG produced a significantly higher level of heat stress when compared to the KD assembly. The stress of both assemblies was significantly raised by the inclusion of the mask. This was demonstrated by an increased sweat rata (KD only), increased rectal temperature, increased epigastric skin temperature, and an increased heart rate. Some of the increase in heart rate due to wearing the mask could not be attributed solely to changes in body temperature.

It is concluded that the protective face mask imposes a significant additional heat stress which increases with the level of the prevailing stress and would indicate a possible source of error in those calculations of heat stress which add the same constant for a clothing condition at all levels of stress.     

Reproducibility of body temperature response to standardized test conditions when assessing clothing

Abstract

The traditional use of core temperature to assess the thermal effects of clothing has recently been questioned. The purpose of this study was to assess the reproducibility of body temperature in five subjects (mean age, 226 ± 1-5 yrs) wearing either athletic clothing or a chemical protective overgarment while exercising at 20°C and at 40°C. The exercise was preceded by a 1 h adaptation period in a controlled environmental chamber. Results indicated that mean group change in rectal temperature (δT_r ) appeared to be reproducible for both garment ensembles at 20°C but not at 40°C. For mean change in oesophageal temperature ( δT_oes ) at 20°C, reproducibility was obtained for the overgarment but not for the athletic garment; at 40°C, mean δT_oes appeared to be reproducible with both garments. However, when individual responses were examined, there was little reproducibility for either δT_r or δT_oes . In addition, these measurements failed to show differences in the types of clothing worn. It was concluded that the use of core temperature to assess heat stress imposed by wearing clothing during exercise may lead to erroneous conclusions.     

Wearer related performance standards for conditioned clothing

Abstract

Estimates, based on American experience of work in the heat, indicate that in the UK, half a million workers or more may be working in thermally uncomfortable and stressfully hot environments. In addition, many will be experiencing cold working conditions and associated discomfort. The role of protective clothing as one of the factors involved in imposing thermal stress is emphasized.

One method of thermal stress control is to provide conditioned garments which warm or cool the wearer as required. The use of ‘air supplied’ garments for cooling is specifically dealt with and the methods of defining their performance reviewed. The application of the concept of ‘per cent wetted skin surface area’ is discussed as one method of defining the performance of air ventilated garments if thermal comfort cannot be achieved. The use of low pressure air for ventilating garments is proposed. The performance of such a system employing a small battery powered blower is defined in terms of the wearers work rate and supply air temperature and volume using the wetted surface area concept. The necessary steps to be taken by manufacturers if they are to develop the market for such conditioned garments are outlined.     

Female upper body and breast skin temperature and thermal comfort following exercise

Breast support reduces breast pain and movement during exercise, however, an extra layer of clothing may affect thermoregulation. This preliminary study investigated female upper body and breast skin temperature and thermal comfort following short-duration exercise. Eight female participants with C-cup breasts had thermal images (infra-red camera, FLIR systems) of the bare breasts, the breasts in two sports bras (composite and polyester) and the abdomen, taken before and after 20 min of exercise at 28^oC. Following exercise, bare-breast, bra and abdomen temperatures reduced by 0.61^oC, 0.92^oC and 2.06^oC, respectively. The polyester sports bra demonstrated greater thermal comfort and enabled a greater change in skin temperature than the composite sports bra. It is concluded that following short-duration exercise, sports bras reduced the cooling ability of the breast. Material properties of the bras affect thermal comfort and post-exercise skin temperature; this should be an important consideration for sports bra manufacturers.

Practitioner summary: This study investigates the effect of sports bras on thermal regulation of the breast following exercise. Sports bras negatively affected the cooling ability of the skin on the breast, with the material properties of the bra affecting thermal comfort following exercise. These results present important considerations for sports bra manufacturers.     

Effects of moisture absorption in clothing on the human heat balance

A theory of moisture absorption in clothing, with the associated effects of heat transfer, was developed and applied in a computer model. The model considers the body, underclothing, an outer layer, and the adjacent air layer. The theory was checked with an experiment involving four subjects. They wore heavy woollen clothing, which was either initially dry or humid, in both a warm and a cool environment. Model calculations and experimental results agree approximately upon the timing and magnitude of the effect of absorbing clothing on heat flows, temperatures and physiological reactions. Contrary to expectations the observed vapour resistance is lower in the heat than in the cold, probably due to differences in sweat distribution. It is pointed out that the usual way to determine the clothing characteristics by means of partitional calorimetry leads to considerable errors when the steady state has not been reached. In clothing that has high absorption properties the transient effects may be sustained for hours. Tests using the model show few beneficial effects of absorbing clothing on thermal sensation.     

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.     

A comparative study on the effects of air gap wind and walking motion on the thermal properties of Arabian Thawbs and Chinese Cheongsams

This paper reports on an experimental investigation on the effects of air gap, wind and walking motion on the thermal properties of traditional Arabian thawbs and Chinese cheongsams. Total thermal resistance (I_t) and vapour resistance (R_e) were measured using the sweating fabric manikin – ‘Walter’, and the air gap volumes of the garments were determined by a 3D body scanner. The results showed the relative changes of I_t and R_e of thawbs due to wind and walking motion are greater than those of cheongsams, which provided an explanation of why thawbs are preferred in extremely hot climate. It is further shown that thermal insulation and vapour resistance of thawbs increase with the air gap volume up to about 71,000 cm³ and then decrease gradually. Thawbs with higher air permeability have significantly lower evaporative resistance particularly under windy conditions demonstrating the advantage of air permeable fabrics in body cooling in hot environments.

Practitioner Summary: This paper aims to better understand the thermal insulation and vapour resistance of traditional Arabian thawbs and Chinese cheongsams, and the relationship between the thermal properties and their fit and design. The results of this study provide a scientific basis for designing ethnic clothing used in hot environments.