Human Thermophysiological Responses Research Articles

Mitigating heat effects in the workplace with a ventilation jacket: Simulations of the whole-body and local human thermophysiological response with a sweating thermal manikin in a warm-dry environment

Climate change is increasingly affecting human well-being and will inevitably impact on occupational sectors in terms of costs, productivity, workers’ health and injuries.Among the cooling garment developed to reduce heat strain, the ventilation jacket could be considered for possible use in workplaces, as it is wearable without limiting the user's mobility and autonomy.In this study, simulations with a sweating manikin are carried out to investigate the effects of a short-sleeved ventilation jacket on human thermophysiological responses in a warm-dry scenario.Simulations were performed in a climatic chamber (air temperature = 30.1 °C; air velocity = 0.29 m/s; relative humidity = 30.0 %), considering two constant levels of metabolic rate M (M1 = 2.4 MET; M2 = 3.2 MET), a sequence of these two (Work), and three levels of fan velocities (lf = 0; lf=2; lf=4).The results revealed a more evident impact on the mean skin temperature (Tsk) compared to the rectal temperature (Tre), with significant decreases (compared to fan-off) at all M levels, for Tsk from the beginning and for Tre from the 61st minute. Skin temperatures of the torso zones decreased significantly (compared to fan-off) at all M levels, and a greater drop was registered for the Back.The fans at the highest level (lf=4) were significantly effective in improving whole-body and local thermal sensations when compared to fan-off, at all M levels.At the intermediate level (lf=2), the statistical significance varied with thermal zone, M and time interval considered.The results of the simulations also showed that the Lower Torso needs to be monitored at M2 level, as the drop in skin temperature could lead to local overcooling and thermal discomfort.Simulations showed the potential effectiveness of the ventilation jacket, but human trials are needed to verify its cooling power in real working conditions.

A numerical tool for assessing human thermal safety and thermal comfort in cold-weather activities.

This paper describes a newly developed software tool to evaluate human thermal safety and thermal comfort in cold-weather activities aimed at guiding users to arrange activity plans and select appropriate clothing ensembles. The software inputs include conditions of activity, environment, human body, and clothing ensemble. It outputs physiological temperatures, cold injury risks, thermal sensations, and thermal comforts in intuitive ways like cloud maps and curves. The software tool is characterized by (1) integration of a thermoregulatory model that predicts human thermophysiological responses under exercise conditions in cold environments, (2) the functions of clothing ensemble database and individual parameter database, (3) the human centric outputs that directly reflect human physiological and mental status, and (4) the user-friendly operation interface and output interface, as well as a wide applicability. The software is validated with human test studies covering ambient temperatures from - 30.6 to 5°C, clothing ensembles from 1.34 to 3.20 clo, and activity intensities from 2 to 9 Mets. The average prediction RMSEs of core temperature, mean skin temperature, thermal sensation, and thermal comfort are 0.16°C, 0.45°C, 0.58, and 1.41, respectively. The software is an advanced expansion to current standards and guidance of cold exposure assessment and a meaningful tool for the fields of occupational health care, cold protection, and environmental ergonomics.

Combination of a simplified one-dimensional human thermoregulatory model with the water circulation temperature control and RO membrane sweating systems in the thermal manikin

Thermal manikins are widely applied in evaluating thermal properties of personal protective equipment and environments, but their adaptability to transient environments are limited to the control algorithm and hardware of the heating and sweating system. This study aims to design and instrument a novel regional thermal manikin system that can automatically regulate the skin temperature and sweating rate under transient environments. A simplified one-dimensional human thermoregulatory model, the water circulation temperature control and RO membrane sweating systems were established to an integrated temperature and sweating control system (ITSCS) in the left calf segment with critical indicators tested. Results demonstrated that the sweating rate, response time and temperature incrementing and declining speeds were reliable for dynamic regulation in thermal manikins, while the control accuracy was acceptable, and average skin temperature deviations in ITSCS from simulation did not exceed 0.2 °C. Thus the ITSCS can be applied to simulate human thermophysiological responses under transient environments.

Numerical simulation of the human thermophysiological responses with a liquid circulating garment: Experimental validation and parametric study

Liquid circulating garments (LCG) can effectively alleviate the heat strain of people in hot environments. This work used a human thermoregulatory model integrated with a thermal and comfort model to comprehensively study the design factors of LCG. The model was firstly validated by human trials and showed good simulation performance in predicting both thermophysiological and subjective responses with LCG in a hot temperature. Then a numerical parametric study was performed to examine the effect of inlet water temperature, clothing insulation, pipe length, and cooling mode on cooling performance under different hot environments. The results indicate that the comfortable inlet water temperatures are 22, 19, and 16 °C under 30, 34, and 38 °C environments, respectively for a standing person wearing an LCG with thermal insulation of 1.0 clo and water pipe length of 8 m. Higher clothing insulation is beneficial for reducing the core and skin temperatures in very hot environments (i.e., 38 °C). The pipe length has a significant impact on the cooling performance. Furthermore, compared to the continuous cooling mode, intermittent cooling in high frequency (i.e., time cycle period = 5 min) can mitigate the heat stress of wearers with less energy consumption. The study could provide a helpful guideline for designing LCG to offer better thermal comfort and energy-saving strategies for people in hot environments.

A three-dimensional thermoregulatory model for predicting human thermophysiological responses in various thermal environments

This study presents a complete virtual three-dimensional (3D) model of human thermophysiological responses by integrating detailed heat dissipation model from human skin to environment through spatially heterogeneous (realistic) clothing into human thermoregulation model by two-way coupling. The model considered various heat and mass transfer mechanisms in air and clothing layers such as conduction, natural convection, forced convection, radiation, and evaporation. The numerical setup of the model was presented and simulated using ANSYS Fluent. The developed model is systematically validated against experimental data obtained from authors of published literatures. To demonstrate the robustness and accuracy of the model, it has been validated for a wide range of ambient temperatures (−10.0 to 45 °C), relative humidity (25–86%), activity levels (0.8–3.5 mets), clothing thermal resistances (0.10–2.95 clo), and evaporative resistances (11.5–800 Pa m2/W) including steady-state and transient exposures. This complete 3D model predicted human thermophysiological responses for a wide range of ambient condition with good accuracy. The average RMSD (root mean square deviation) of predicted core and mean skin temperatures was 0.21 °C (maximum RMSD = 0.33 °C) and 0.56 °C (maximum RMSD = 1.03 °C), compared to average standard deviation in measured data 0.26 °C and 0.58 °C, respectively. The model is also able to predict the local skin temperature with an average RMSD of 0.64 °C. Therefore, this newly developed model can be served as a useful tool in analysing human thermophysiological responses and heat stress for any given thermal environment and clothing setting.

The Effects of Upper-Body Exoskeletons on Human Metabolic Cost and Thermal Response during Work Tasks-A Systematic Review.

Background: New wearable assistive devices (exoskeletons) have been developed for assisting people during work activity or rehabilitation. Although exoskeletons have been introduced into different occupational fields in an attempt to reduce the risk of work-related musculoskeletal disorders, the effectiveness of their use in workplaces still needs to be investigated. This systematic review focused on the effects of upper-body exoskeletons (UBEs) on human metabolic cost and thermophysiological response during upper-body work tasks. Methods: articles published until 22 September 2020 were selected from Scopus, Web of Science, and PubMed for eligibility and the potential risk of bias was assessed. Results: Nine articles resulted in being eligible for the metabolic aspects, and none for the thermal analysis. All the studies were based on comparisons between conditions with and without exoskeletons and considered a total of 94 participants (mainly males) performing tasks involving the trunk or overhead work, 7 back-support exoskeletons, and 1 upper-limb support exoskeleton. Eight studies found a significant reduction in the mean values of the metabolic or cardiorespiratory parameters considered and one found no differences. Conclusions: The reduction found represents a preliminary finding that needs to be confirmed in a wider range of conditions, especially in workplaces, where work tasks show different characteristics and durations compared to those simulated in the laboratory. Future developments should investigate the dependence of metabolic cost on specific UBE design approaches during tasks involving the trunk and the possible statistical correlation between the metabolic cost and the surface ElectroMyoGraphy (sEMG) parameters. Finally, it could be interesting to investigate the effect of exoskeletons on the human thermophysiological response.

Estimation of Time-Course Core Temperature and Water Loss in Realistic Adult and Child Models with Urban Micrometeorology Prediction.

Ambient conditions may change rapidly and notably over time in urban areas. Conventional indices, such as the heat index and wet bulb globe temperature, are useful only in stationary ambient conditions. To estimate the risks of heat-related illness, human thermophysiological responses should be followed for ambient conditions in the time domain. We develop a computational method for estimating the time course of core temperature and water loss by combining micrometeorology and human thermal response. We firstly utilize an urban micrometeorology prediction to reproduce the environment surrounding walkers. The temperature elevations and sweating in a standard adult and child are then estimated for meteorological conditions. With the integrated computational method, we estimate the body temperature and thermophysiological responses for an adult and child walking along a street with two routes (sunny and shaded) in Tokyo on 7 August 2015. The difference in the core temperature elevation in the adult between the two routes was 0.11 °C, suggesting the necessity for a micrometeorology simulation. The differences in the computed body core temperatures and water loss of the adult and child were notable, and were mainly characterized by the surface area-to-mass ratio. The computational techniques will be useful for the selection of actions to manage the risk of heat-related illness and for thermal comfort.

Model validation and parametric study on a personal heating clothing system (PHCS) to help occupants attain thermal comfort in unheated buildings

Personal heating clothing systems (PHCS) incorporated with electrical heating elements have shown its great potential to help occupants attain thermal comfort in cold built environments. Presently there is a lack of a comprehensive study to optimize the PHCS's performance. In this work, a newly developed complete 3D model was used to systematically examine the factors affecting the PHCS's heating performance in various cold unheated built environments. Effects of ambient temperature, clothing insulation, heating power, heating mode and metabolic rate on the PHCS's performance were investigated by performing a numerical parametric study. Validation data have demonstrated that the 3D model could precisely predict human thermophysiological responses while wearing PHCS in the built environment. At 15.0 °C indoor temperature and metabolic rate of 1.6 met, wearing a PHCS with thermal insulation of 1.0 clo and heating power of 20 W could help occupants attain thermal comfort. It was also found that compared with continuous heating, intermittent heating at a high heating frequency could contribute to saving energy without compromise of body temperature reduction. Furthermore, metabolic rate has a significant impact on thermophysiological responses and the mean heaters' temperature. Hence, the selection and operation of a PHCS should be based on the nature of occupant activities. Occupants are advised to adjust the heating power to a lower level when performing more demanding activities because the need for auxiliary heating is not as high as that in the case when occupants are resting or performing seated office activities.

Numerical analysis of cooling effect of hybrid cooling clothing incorporated with phase change material (PCM) packs and air ventilation fans

Hybrid personal cooling garment incorporating phase change materials (PCMs) and ventilation fans is developed recently and found to be effective from the standpoint of cooling effect and thermal comfort of wearers under different environmental conditions. In the present study, a numerical model is developed to analyse heat and moisture transfer through the hybrid personal cooling garment and understand underlying physical mechanisms. The clothing heat and moisture transfer model is coupled with a multi-node human thermoregulation model to be able to determine human thermo-physiological responses under dynamic environmental conditions. The multi-node Tanabe’s model is modified to take into account PCMs and non-PCMs covered parts in body segments. Apparent heat capacity method is used to deal with the phase change behaviour. The moisture barrier effect of PCM packs along with the evaporation and condensation at the surface of PCM packs are also considered. Results obtained from the newly developed numerical model are compared with the human trial data. Mean skin temperature and core temperature obtained from the numerical model are found to be in good agreement with the experimental results. The model is further used to analyse temperature and moisture distributions within the clothing and heat transfer through hybrid personal cooling clothing. Significantly lower clothing system temperature, core and mean skin temperatures are obtained for hybrid personal cooling clothing as compared to air ventilation clothing. Effects of PCMs and air ventilation are also analysed on heat transfer through the hybrid personal cooling clothing. Furthermore, performance of various personal cooling approaches involving PCMs and air ventilation is compared with the normal clothing under the warm environmental condition. It is found that the hybrid personal cooling clothing exhibits better cooling performance as compared to clothing with other cooling approaches involving either only PCMs or only air ventilation fans.

Human cold stress of strong local-wind "Hijikawa-arashi" in Japan, based on the UTCI index and thermo-physiological responses.

We investigated the cold stress caused by a strong local wind called "Hijikawa-arashi," through in situ vital measurements and the Universal Thermal Climate Index (UTCI). This wind is a very interesting winter phenomenon, localized in an area within 1km of the seashore in Ozu City, Ehime Prefecture in Japan. When a strong Hijikawa-arashi (HA) occurred at 14-15ms-1, the UTCI decreased to - 30°C along the bridge where commuting residents are the most exposed to strong and cold winds. On the bridge, most participants in our experiment felt "very cold" or "extremely cold." The UTCI of HA can be predicted from a multiple regression equation using wind speed and air temperature. The cold HA wind is also harmful to human thermo-physiological responses. It leads to higher blood pressure and increased heart rate, both of which act as cardiovascular stress triggers. Increases of 6-10mmHg and 3-6bpm for every 10°C reduction in UTCI were seen on all observational days, including HA and non-HA days. In fact, the participants' body skin temperatures decreased by approximately 1.2 to 1.7 °C for every 10°C reduction in UTCI. Thus, the UTCI variation due to the HA outbreak corresponded well with the cold sensation and thermo-physiological responses in humans. This result suggests that daily UTCI monitoring enables the prediction of thermo-physiological responses to the HA cold stress.

Local air gap thickness and contact area models for realistic simulation of human thermo-physiological response.

To evaluate the quality of new energy-saving and performance-supporting building and urban settings, the thermal sensation and comfort models are often used. The accuracy of these models is related to accurate prediction of the human thermo-physiological response that, in turn, is highly sensitive to the local effect of clothing. This study aimed at the development of an empirical regression model of the air gap thickness and the contact area in clothing to accurately simulate human thermal and perceptual response. The statistical model predicted reliably both parameters for 14 body regions based on the clothing ease allowances. The effect of the standard error in air gap prediction on the thermo-physiological response was lower than the differences between healthy humans. It was demonstrated that currently used assumptions and methods for determination of the air gap thickness can produce a substantial error for all global, mean, and local physiological parameters, and hence, lead to false estimation of the resultant physiological state of the human body, thermal sensation, and comfort. Thus, this model may help researchers to strive for improvement of human thermal comfort, health, productivity, safety, and overall sense of well-being with simultaneous reduction of energy consumption and costs in built environment.

Talk to the Hand: U.S. Army Biophysical Testing.

Many people are unaware of the science underlying the biophysical properties of Soldier clothing and personal protective equipment, yet there is a well-refined biomedical methodology initiated by Army physiologists in World War II. This involves a methodical progression of systematic material testing technologies, computer modeling, and human testing that enables more efficient development and rapid evaluation of new concepts for Soldier health and performance. Sophisticated manikins that sweat and move are a central part of this testing continuum. This report briefly summarizes the evolution and use of one specialized form of the manikin technologies, the thermal hand model, and its use in research on Soldier hand-wear items that sustain dexterity and protect the hand in extreme environments. Thermal manikin testing methodologies were developed to provide an efficient and consistent analytical tool for the rapid evaluation of new clothing concepts. These methods have been upgraded since the original World War II and Korean War eras to include articulation and sweating capabilities, as characterized and illustrated in this article. The earlier "retired" versions of thermal hand models have now been transferred to the National Museum of Health and Science. The biophysical values from manikin testing are critical inputs to the U.S. Army Research Institute of Environmental Medicine mathematical models that provide predictions of soldier comfort, duration of exposure before loss of manual dexterity, and time to significant risk of freezing (skin temperature <-1°C) and nonfreezing cold injuries (skin temperature <5°C). The greater thickness of better insulated handwear reduces dexterity and also increases surface area which makes added insulation increasingly less effective in retaining heat. Measurements of both thermal resistance (insulation) and evaporative resistance (permeability) collectively characterize the biophysical properties and enable mathematical modeling of the human thermophysiological responses. This information can help guide the hand-wear development and selection process which often requires trade-offs between factors such as material, cost, and sizing. Soldier hands provide fine motor dexterity in tactical functions, ranging from pulling a trigger to pulling a parachute ripcord; thus, protecting hand function is critical to soldier readiness. Also, the importance of protection against nonbattle cold injuries was highlighted during World War II in northern Europe, in the Aleutian Islands, and later in Korea. The U.S. Army has been on the forefront of the biophysical analysis of clothing including gloves since environmental research was established at the Armored Medical Research Laboratory and Climatic Research Laboratory during World War II. U.S. Army Research Institute of Environmental Medicine does not make the equipment but works with their Natick Soldier Research, Development, and Engineering Center partners to make the equipment better.

Comparison of fabric skins for the simulation of sweating on thermal manikins.

Sweating is an important thermoregulatory process helping to dissipate heat and, thus, to prevent overheating of the human body. Simulations of human thermo-physiological responses in hot conditions or during exercising are helpful for assessing heat stress; however, realistic sweating simulation and evaporative cooling is needed. To this end, thermal manikins dressed with a tight fabric skin can be used, and the properties of this skin should help human-like sweat evaporation simulation. Four fabrics, i.e., cotton with elastane, polyester, polyamide with elastane, and a skin provided by a manikin manufacturer (Thermetrics) were compared in this study. The moisture management properties of the fabrics have been investigated in basic tests with regard to all phases of sweating relevant for simulating human thermo-physiological responses, namely, onset of sweating, fully developed sweating, and drying. The suitability of the fabrics for standard tests, such as clothing evaporative resistance measurements, was evaluated based on tests corresponding to the middle phase of sweating. Simulations with a head manikin coupled to a thermo-physiological model were performed to evaluate the overall performance of the skins. The results of the study showed that three out of four evaluated fabrics have adequate moisture management properties with regard to the simulation of sweating, which was confirmed in the coupled simulation with the head manikin. The presented tests are helpful for comparing the efficiency of different fabrics to simulate sweat-induced evaporative cooling on thermal manikins.

Thermo-physiological impact of different firefighting protective clothing ensembles in a hot environment

It is currently unclear how the assembly of different fabric layers of personal protective clothing (PPC) contributes to differences in thermal comfort among garments. Therefore, we used two different approaches to investigate the effect of PPC on body heat dissipation: a technical characterization of textiles (using sweating Torso methodology) and thermo-physiological wearing trials. We hypothesized that the technical characterization provides a similar outcome compared to the wearing trials and, thus, proves to have high thermo-physiological relevance. Thirteen different PPC were investigated using the sweating Torso methodology. Three out of these thirteen were then selected for inclusion in a series of human subject trials in a hot environment. Results from human trials and Torso testing were related to each other. The thermal and evaporative properties of the selected PPC typically differed and effects were observed for the thermo-physiological responses of human study participants. Differences in Torso surface temperature of up to 9℃ and moisture accumulation in the protective clothing systems of up to 184 g·m–2 were detected using the sweating Torso methodology. Moderate intensity exercise with the human study participants induced textile-dependent differences of up to 0.9 ± 0.2℃ ( P &lt; 0.001) and 1.2 ± 0.2℃ ( P = 0.008) for excessive core body and excessive skin temperature, respectively. Using the sweating Torso methodology, physiologically relevant differences in textile performance could be detected among different PPC. Consequently, sweating Torso is a relevant tool to gain insight into human thermo-physiological responses to different PPC with similar end-use based on their dry and wet heat transfer characteristics.

Evaluation of Protective Ensemble Thermal Characteristics Through Sweating Hot Plate, Sweating Thermal Manikin, and Human Tests

The purpose of this study was to evaluate the predictive capability of fabric Total Heat Loss (THL) values on thermal stress that Personal Protective Equipment (PPE) ensemble wearers may encounter while performing work. A series of three tests, consisting of the Sweating Hot Plate (SHP) test on two sample fabrics and the Sweating Thermal Manikin (STM) and human performance tests on two single-layer encapsulating ensembles (fabric/ensemble A = low THL and B = high THL), was conducted to compare THL values between SHP and STM methods along with human thermophysiological responses to wearing the ensembles. In human testing, ten male subjects performed a treadmill exercise at 4.8 km and 3% incline for 60 min in two environmental conditions (mild = 22°C, 50% relative humidity (RH) and hot/humid = 35°C, 65% RH). The thermal and evaporative resistances were significantly higher on a fabric level as measured in the SHP test than on the ensemble level as measured in the STM test. Consequently the THL values were also significantly different for both fabric types (SHP vs. STM: 191.3 vs. 81.5 W/m2 in fabric/ensemble A, and 909.3 vs. 149.9 W/m2 in fabric/ensemble B (p < 0.001). Body temperature and heart rate response between ensembles A and B were consistently different in both environmental conditions (p < 0.001), which is attributed to significantly higher sweat evaporation in ensemble B than in A (p < 0.05), despite a greater sweat production in ensemble A (p < 0.001) in both environmental conditions. Further, elevation of microclimate temperature (p < 0.001) and humidity (p < 0.01) was significantly greater in ensemble A than in B. It was concluded that: (1) SHP test determined THL values are significantly different from the actual THL potential of the PPE ensemble tested on STM, (2) physiological benefits from wearing a more breathable PPE ensemble may not be feasible with incremental THL values (SHP test) less than approximately 150–200 W·m2, and (3) the effects of thermal environments on a level of heat stress in PPE ensemble wearers are greater than ensemble thermal characteristics.

Validation of the Fiala multi-node thermophysiological model for UTCI application

The important requirement that COST Action 730 demanded of the physiological model to be used for the Universal Thermal Climate Index (UTCI) was its capability of accurate simulation of human thermophysiological responses across a wide range of relevant environmental conditions, such as conditions corresponding to the selection of all habitable climates and their seasonal changes, and transient conditions representing the temporal variation of outdoor conditions. In the first part of this study, available heat budget/two-node models and multi-node thermophysiological models were evaluated by direct comparison over a wide spectrum of climatic conditions. The UTCI-Fiala model predicted most reliably the average human thermal response, as shown by least deviations from physiologically plausible responses when compared to other models. In the second part of the study, this model was subjected to extensive validation using the results of human subject experiments for a range of relevant (steady-state and transient) environmental conditions. The UTCI-Fiala multi-node model proved its ability to predict adequately the human physiological response for a variety of moderate and extreme conditions represented in the COST 730 database. The mean skin and core temperatures were predicted with average root-mean-square deviations of 1.35 ± 1.00°C and 0.32 ± 0.20°C, respectively.

Prediction of human thermophysiological responses during shower bathing

This study develops a model to predict the thermophysiological response of the human body during shower bathing. Despite the needs for the quantitative evaluation of human body response during bathing for thermal comfort and safety, the complicated mechanisms of heat transfer at the skin surface, especially during shower bathing, have disturbed the development of adequate models. In this study, an initial modeling approach is proposed by developing a simple heat transfer model at the skin surface during shower bathing applied to Stolwijk's human thermal model. The main feature of the model is the division of the skin surface into three parts: a dry part, a wet part without water flow, and a wet part with water flow. The area ratio of each part is decided by a simple formula developed from a geometrical approach based on the shape of the Stolwijk's human thermal model. At the same time, the convective heat transfer coefficient between the skin and the flowing water is determined experimentally. The proposed model is validated by a comparison with the results of human subject experiments under controlled and free shower conditions. The model predicts the mean skin temperature during shower fairly well both for controlled and free shower bathing styles.

Effects of fabric surface energy on human thermophysiological responses during exercise and recovery

The present paper reports a study on influences of fabric surface energy of cotton and polyester garments on clothing microclimates and human thermophysiological responses during intermittent exercise and recovery. Eight healthy males wearing the garments prepared performed exercises and rest according to the following protocol: rest for 30 min, run on treadmill for total 60 min of three sessions with different intensity and duration, and then sit quietly for 30 min for recovery, all at 30 °C and relative humidity of 30 %, while the microclimate humidity (H mc ) and temperature (T mc ), the clothing outside surface humidity (H co ) and temperature (T co ), the skin temperatures and ear canal temperature (T ear_canal ) were measured. The garments are made of: (a) hydrophilic and hydrophobic cotton knitted fabrics, and (b) hydrophilic and hydrophobic polyester knitted fabrics. During and after exercise, for cotton, hydrophilic garment resulted in significant lowerΔH mc , ΔH co , ΔT mc during recovery, higher $$\Delta \overline {\rm T} _{sk} $$ , lowerΔT ear_canal andΔT forehead . For polyester, hydrophilic garment resulted in significantly lowerΔH co , ΔT co , higher $$\Delta \overline {\rm T} _{sk} $$ , higherΔT forehead during E1, E2 and recovery session but lower during E3. In summary, surface energy of cotton garments had significant influences on human thermophysiological responses during exercise and recovery, and hydrophilic cotton garment was better than hydrophobic one to reduce heat stress. Surface energy of polyester garments had influences of lower significance, and hydrophilic garment appeared better than hydrophobic garment.

Effect of Fabric Liquid Water Transfer Behavior on Human Thermophysiological Responses and Clothing Microclimate during Exercise and Recovery

This paper reports a study on the effects of fabric liquid water transfer behavior on human thermophysiological responses and clothing microclimate. Both cotton and polyester fabrics were treated to have different liquid water transfer properties. With moisture management (MM) treatment, the fabrics can transfer liquid water from inner surface (close to skin) to outer surface (close to surrounding environment) during wearing while keeping skin dry. With reversed moisture management (RMM) treatment, the inner layer of the fabric is water absorbency, liquid water is difficult to be transferred to outer surface. Two sets of garments were made of MM and RMM fabrics for both cotton and polyester respectively. A series of wear trials were conducted by asking human subjects to wear these garments according to a specially designed experimental protocol. The microclimate humidity and temperature, skin temperature and ear canal temperature were recorded. MM cotton garment caused significant lower absolute humidity outside clothing (Hco) during exercise and recovery, higher temperature outside clothing (Tco), higher mean skin temperature (Tsk) and lower ear canal temperature (Tear_canal) during recovery than RMM cotton. Polyester MM garment caused significant higher Hco during exercise and higher Tsk than RMM polyester. For both cotton and polyester, MM garment is better than RMM garment to reduce heat stress during exercise and recovery in temperature of 30 °C and relative humidity of 30%.

Human thermophysiological response to high intensity radiation fluxes near a forest fire line

Human thermophysiological response to high intensity radiation fluxes near a forest fire line