The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Graham P. Bates - One of the best experts on this subject based on the ideXlab platform.
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the risk of heat exhaustion at a deep underground metalliferous mine in relation to surface Temperatures
Occupational Medicine, 2000Co-Authors: A M Donoghue, Graham P. BatesAbstract:The risk of heat exhaustion at a deep underground metalliferous mine was assessed in relation to thermal conditions prevailing on the surface. For each day of a 1-year prospective case series of heat exhaustion, surface 24-h mean wet and dry bulb Temperatures were recorded. From this data, 24-h mean wet bulb Globe Temperatures were derived using certain assumptions. The three surface Temperature variables were significantly higher on those days on which heat exhaustion occurred, compared to those days on which it did not occur (P < 0.001). The relative risk of heat exhaustion on days when the 24-h mean wet bulb Globe Temperature was in the range 26.0-28.0°C was 4.82 (95% confidence interval 2.12-10.96). Surface Temperature data could be used at this mine to warn miners about the risk of heat exhaustion.
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heat exhaustion in a deep underground metalliferous mine
Occupational and Environmental Medicine, 2000Co-Authors: Michael A Donoghue, Murray J Sinclair, Graham P. BatesAbstract:OBJECTIVES To examine the incidence, clinical state, personal risk factors, haematology, and biochemistry of heat exhaustion occurring at a deep underground metalliferous mine. To describe the underground thermal conditions associated with the occurrence of heat exhaustion. METHODS A 1 year prospective case series of acute heat exhaustion was undertaken. A history was obtained with a structured questionnaire. Pulse rate, blood pressure, tympanic Temperature, and specific gravity of urine were measured before treatment. Venous blood was analysed for haematological and biochemical variables, during the acute presentation and after recovery. Body mass index (BMI) and maximum O 2 consumption (V˙o 2 max) were measured after recovery. Psychrometric wet bulb Temperature, dry bulb Temperature, and air velocity were measured at the underground sites where heat exhaustion had occurred. Air cooling power and psychrometric wet bulb Globe Temperature were derived from these data. RESULTS 106 Cases were studied. The incidence of heat exhaustion during the year was 43.0 cases / million man-hours. In February it was 147 cases / million man-hours. The incidence rate ratio for mines operating below 1200 m compared with those operating above 1200 m was 3.17. Mean estimated fluid intake was 0.64 l/h (SD 0.29, range 0.08–1.50). The following data were increased in acute presentation compared with recovery (p value, % of acute cases above the normal clinical range): neutrophils (p 2 (SD 49, range 33–290) Mean psychrometric wet bulb Globe Temperature was 31.5°C (SD 2.0, range 25.2–35.3). Few cases ( 1.56 m/s, air cooling power >248 W/m 2 , or psychrometric wet bulb Globe Temperature CONCLUSION Heat exhaustion in underground miners is associated with dehydration, neutrophil leukocytosis, eosinopenia, metabolic acidosis, increased glucose and ferritin, and a mild rise in creatine kinase, aspartate transaminase, and lactate dehydrogenase. Heat cramps are associated with dehydration but not hyponatraemia. The incidence of heat exhaustion increases during summer and at depth. An increased fluid intake is required. Heat exhaustion would be unlikely to occur if ventilation and refrigeration achieved air cooling power >250 W/m 2 at all underground work sites.
Andrew Grundstein - One of the best experts on this subject based on the ideXlab platform.
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variations in athlete heat loss potential between hot dry and warm humid environments at equivalent wet bulb Globe Temperature thresholds
Journal of Athletic Training, 2020Co-Authors: Jennifer K Vanos, Andrew GrundsteinAbstract:CONTEXT Many organizations associated with sports medicine recommend using wet-bulb Globe Temperature (WBGT)-based activity-modification guidelines that are uniform across the country. However, no consideration has been given to whether the WBGT thresholds are appropriate for different weather conditions, such as warm-humid (WH) relative to hot-dry (HD), based on known differences in physiological responses to these environments. OBJECTIVE To identify if personnel in regions with drier conditions and greater evaporative cooling potential should consider using WBGT-based activity-modification thresholds that differ from those in more humid weather. DESIGN Observational study. SETTING Weather stations across the contiguous United States. MAIN OUTCOME MEASURE(S) A 15-year hourly WBGT dataset from 217 weather stations across the contiguous United States was used to identify particular combinations of Globe Temperature, wet-bulb Temperature, and air Temperature that produce WBGTs of 27.9°C, 30.1°C, and 32.3°C. A total of 71 302 observations were clustered into HD and WH environmental conditions. From these clusters, maximum heat-loss potential and heat-flux values were modeled at equivalent WBGT thresholds with various activity levels, clothing, and equipment configurations. RESULTS We identified strong geographic patterns, with HD conditions predominant in the western half and WH conditions predominant in the eastern half of the country. Heat loss was systematically greater in HD than in WH conditions, indicating an overall less stressful environment, even at equivalent WBGT values. At a WBGT of 32.3°C, this difference was 11 W·m-2 at an activity velocity of 0.3 m·s-1, which doubled for an activity velocity of 0.7 m·s-1. The HD and WH difference increased with the WBGT value, demonstrating that evaporative cooling differences between HD and WH conditions were even greater at a higher, rather than lower, WBGT. CONCLUSIONS Potential heat loss was consistently greater in HD than in WH environments despite equal WBGTs. These findings support the need for further clinical studies to determine the appropriate WBGT thresholds based on environmental and physiological limits to maximize safety while avoiding unnecessary limitations.
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assessment of the australian bureau of meteorology wet bulb Globe Temperature model using weather station data
International Journal of Biometeorology, 2018Co-Authors: Andrew Grundstein, Earl R CooperAbstract:Exertional heat illnesses affect thousands of athletes each year and are a leading cause of death in sports. The wet bulb Globe Temperature (WBGT) is widely used as a heat stress metric in athletics for adjusting activities. The WBGT can be measured on-site with portable sensors, but instrument cost may provide a barrier for usage. Modeling WBGT from weather station data, then, presents an affordable option. Our study compares two WBGT models of varying levels of sophistication: the Australian Bureau of Meteorology (ABM) model which uses only Temperature and humidity as inputs and a physically based model by Liljegren that incorporates Temperature, humidity, wind speed, and solar radiation in determining WBGT outputs. The setting for the study is 19 University of Georgia Weather Network stations selected from across the state of Georgia, USA, over a 6-year period (2008–2014) during late summer and early fall months. Results show that the ABM model’s performance relative to the Liljegren model varies based on time of day and weather conditions. WBGTs from the ABM model are most similar to those from the Liljegren model during midday when the assumption of moderately high sun most frequently occurs. We observed increasingly large positive biases with the ABM model both earlier and later in the day during periods with lower solar radiation. Even during midday, large (≥ 3 °C) underestimates may occur during low wind conditions and overestimates during periods with high cloud cover. Such differences can lead to inaccurate activity modification and pose dangers for athletes either by underestimating heat-related hazards or by imposing an opportunity cost if practice activities are limited by overestimating the heat hazard.
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an evaluation of portable wet bulb Globe Temperature monitor accuracy
Journal of Athletic Training, 2017Co-Authors: Earl R Cooper, Andrew Grundstein, Adam B Rosen, Jessica Dysart Miles, Patrick CurryAbstract:Context: Wet bulb Globe Temperature (WBGT) is the gold standard for assessing environmental heat stress during physical activity. Many manufacturers of commercially available instruments fail to report WBGT accuracy. Objective: To determine the accuracy of several commercially available WBGT monitors compared with a standardized reference device. Design: Observational study. Setting: Field test. Patients or Other Participants: Six commercially available WBGT devices. Main Outcome Measure(s): Data were recorded for 3 sessions (1 in the morning and 2 in the afternoon) at 2-minute intervals for at least 2 hours. Mean absolute error (MAE), root mean square error (RMSE), mean bias error (MBE), and the Pearson correlation coefficient (r) were calculated to determine instrument performance compared with the reference unit. Results: The QUESTemp° 34 (MAE = 0.24°C, RMSE = 0.44°C, MBE = –0.64%) and Extech HT30 Heat Stress Wet Bulb Globe Temperature Meter (Extech; MAE = 0.61°C, RMSE = 0.79°C, MBE = 0.44%) dem...
A M Donoghue - One of the best experts on this subject based on the ideXlab platform.
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the risk of heat exhaustion at a deep underground metalliferous mine in relation to surface Temperatures
Occupational Medicine, 2000Co-Authors: A M Donoghue, Graham P. BatesAbstract:The risk of heat exhaustion at a deep underground metalliferous mine was assessed in relation to thermal conditions prevailing on the surface. For each day of a 1-year prospective case series of heat exhaustion, surface 24-h mean wet and dry bulb Temperatures were recorded. From this data, 24-h mean wet bulb Globe Temperatures were derived using certain assumptions. The three surface Temperature variables were significantly higher on those days on which heat exhaustion occurred, compared to those days on which it did not occur (P < 0.001). The relative risk of heat exhaustion on days when the 24-h mean wet bulb Globe Temperature was in the range 26.0-28.0°C was 4.82 (95% confidence interval 2.12-10.96). Surface Temperature data could be used at this mine to warn miners about the risk of heat exhaustion.
D J Marlin - One of the best experts on this subject based on the ideXlab platform.
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an index of the environmental thermal load imposed on exercising horses and riders by hot weather conditions
Equine Veterinary Journal, 2010Co-Authors: R C Schroter, D J MarlinAbstract:Summary There is a need to determine objectively the environmental heat load imposed on horses competing to an international standard in 3-day-events in environments where there is likely to be a high level of radiation added to high ambient Temperatures and relative humidity; the presently used FEI ‘Comfort Index’ is severely limited in its applicability. It is proposed that the Wet Bulb Globe Temperature (WBGT) Index be used. This index was originally established for man exercising strenuously under harsh climatic conditions with high solar radiation levels. It may be defined as: WBGT = 0.7Twb + 0.3Tg where Twb is the wet bulb Temperature of the ambient air, measured in the shade and Tg is the black Globe Temperature. Climatic conditions should be monitored continuously at a site representative of the detailed topography and nature of the terrain of the competition course. The upper limit for the index for competitions involving fit, fully acclimatised horses, running on ground of optimal going, is recommended to be 32.5°C. This limit should be reduced, by an as yet undetermined amount, for unacclimatised and unfit horses or when the going is less good.
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an index of the environmental thermal load imposed on exercising horses and riders by hot weather conditions
Equine Veterinary Journal, 2010Co-Authors: R C Schroter, D J MarlinAbstract:There is a need to determine objectively the environmental heat load imposed on horses competing to an international standard in 3-day-events in environments where there is likely to be a high level of radiation added to high ambient Temperatures and relative humidity; the presently used FEI 'Comfort Index' is severely limited in its applicability. It is proposed that the Wet Bulb Globe Temperature (WBGT) Index be used. This index was originally established for man exercising strenuously under harsh climatic conditions with high solar radiation levels. It may be defined as: WBGT = 0.7Twb + 0.3Tg where Twb is the wet bulb Temperature of the ambient air, measured in the shade and Tg is the black Globe Temperature. Climatic conditions should be monitored continuously at a site representative of the detailed topography and nature of the terrain of the competition course. The upper limit for the index for competitions involving fit, fully acclimatised horses, running on ground of optimal going, is recommended to be 32.5 degrees C. This limit should be reduced, by an as yet undetermined amount, for unacclimatised and unfit horses or when the going is less good.
Tohru Mochida - One of the best experts on this subject based on the ideXlab platform.
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heat balance model for a human body in the form of wet bulb Globe Temperature indices
Journal of Thermal Biology, 2018Co-Authors: Tomonori Sakoi, Tohru Mochida, Yoshihito Kurazumi, Kohei Kuwabara, Yosuke Horiba, Shin-ichi SawadaAbstract:Abstract The purpose of this study is to expand the empirically derived wet bulb Globe Temperature (WBGT) index to a rational thermal index based on the heat balance for a human body. We derive the heat balance model in the same form as the WBGT for a human engaged in moderate intensity work with a metabolic heat production of 174 W/m2 while wearing typical vapor-permeable clothing under shady and sunny conditions. Two important relationships are revealed based on this derivation: (1) the natural wet bulb and black Globe Temperature coefficients in the WBGT coincide with the heat balance equation for a human body with a fixed skin wettedness of approximately 0.45 at a fixed skin Temperature; and (2) the WBGT can be interpreted as the environmental potential to increase skin Temperature rather than the heat storage rate of a human body. We propose an adjustment factor calculation method that supports the application of WBGT for humans dressed in various clothing types and working under various air velocity conditions. Concurrently, we note difficulties in adjusting the WBGT by using a single factor for humans wearing vapor-impermeable protective clothing. The WBGT for shady conditions does not need adjustment depending on the positive radiant field (i.e., when a radiant heat source exists), whereas that for the sunny condition requires adjustments because it underestimates heat stress, which may result in insufficient human protection measures.
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Expansion of effective wet bulb Globe Temperature for vapor impermeable protective clothing.
Journal of thermal biology, 2017Co-Authors: Tomonori Sakoi, Tohru Mochida, Yoshihito Kurazumi, Shin-ichi Sawada, Yohsuke Horiba, Kohei KuwabaraAbstract:The wet bulb Globe Temperature (WBGT) is an effective measure for risk screening to prevent heat dISOrders. However, a heat risk evaluation by WBGT requires adjustments depending on the clothing. In this study, we proposed a new effective WBGT (WBGTeff*) for general vapor permeable clothing ensembles and vapor impermeable protective clothing that is applicable to occupants engaged in moderate intensity work with a metabolic heat production value of around 174W/m2. WBGTeff* enables the conversion of heat stress into the scale experienced by the occupant dressed in the basic clothing ensemble (work clothes) based on the heat balances for a human body. We confirmed that WBGTeff* was effective for expressing the critical thermal environments for the prescriptive zones for occupants wearing vapor impermeable protective clothing. Based on WBGTeff*, we succeeded in clarifying how the weights for natural wet bulb, Globe, and air Temperatures and the intercept changed depending on clothing properties and the surrounding environmental factors when heat stress is expressed by the weighted sum of natural wet bulb, Globe, and air Temperatures and the intercept. The weight of environmental Temperatures (Globe and air Temperatures) for WBGTeff* for vapor impermeable protective clothing increased compared with that for general vapor permeable clothing, whereas that of the natural wet bulb Temperature decreased. For WBGTeff* in outdoor conditions with a solar load, the weighting ratio of Globe Temperature increased and that of air Temperature decreased with air velocity. Approximation equations of WBGTeff* were proposed for both general vapor permeable clothing ensembles and for vapor impermeable protective clothing.
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concept of the equivalent wet bulb Globe Temperature index for indicating safe thermal occupational environments
Building and Environment, 2013Co-Authors: Tomonori Sakoi, Tohru MochidaAbstract:We propose the concept of the equivalent wet bulb Globe Temperature (eWBGT) index, which requires no adjustment procedures to indicate the upper limit of safe thermal occupational environments in various conditions. We clarify that the original wet bulb Globe Temperature (WBGT) is an index that expresses the heat storage rate of the human body (S) in its standard condition for acclimatized workers, and demonstrate the relationship between S and WBGT in the standard condition. Based on these findings, we introduce the concept of the eWBGT, which enables conversion of the heat risk in a given condition into the WBGT heat risk scale in the standard condition. The eWBGT estimates heat strain of S under a given condition by using the heat balance equation for the human body. S was converted into the corresponding WBGT heat stress risk scale by referring to the relation between the WBGT and S in the standard condition. The eWBGT changes with the heat and vapor transfer properties of clothing, even when the air Temperature, thermal radiation, water vapor pressure, and air velocity are constant. The eWBGT increases as the thermal insulation of clothing increases, and the influence of environmental water vapor pressure on the eWBGT decreases with decreasing vapor permeability index for the clothing layer. The eWBGT has the potential to provide a more accurate evaluation of the effects of heat and vapor transfer properties of clothing on occupational heat risk than the original WBGT.
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derivation and analysis of the indoor wet bulb Globe Temperature index wbgt with a human thermal engineering approach part 1 properties of the wbgt formula for indoor conditions with no solar radiation
2007Co-Authors: Kouhei Kuwabara, Tohru Mochida, Tomonori SakoiAbstract:SUMMARY The authors present a theoretical derivation of the WBGT for mula for outdoor conditions that was originally developed from the results of experiments on human subjects, based on a heat balance equation between the human body and its outdoor environment. The three coefficients of wet bulb Temperature Tw, Globe Temperature Tg, and air Temperature Ta were expressed in almost the same way as in the indoor WBGT formula, but they contain a new element characterizing solar radiation. In addition, we calculated the coefficients in the theoretically derived formula, changing the amounts of metabolic activity, clothing worn, wind velocity, and solar radiation. We obtained the new formula WBGT = 0.84Tw + 0.30Tg – 0.08Ta, characterized by a negative coefficient of air Temperature Ta, as an alternative to the original outdoor formula WBGT = 0.7Tw + 0.2Tg + 0.1Ta. Finally, we indicated the characteristics of the WBGT as an index as well as instructions for use.