scholarly journals Heat Stress Management in the Military: Wet-Bulb Globe Temperature Offsets for Modern Body Armor Systems

2021 ◽  
pp. 001872082110052
Author(s):  
Andrew P. Hunt ◽  
Adam W. Potter ◽  
Denise M. Linnane ◽  
Xiaojiang Xu ◽  
Mark J. Patterson ◽  
...  
Keyword(s):  
Core Temperature ◽  
Environmental Conditions ◽  
Body Armor ◽  
Body Core Temperature ◽  
Wet Bulb Globe Temperature ◽  
Exertional Heat Illness ◽  
Ballistic Protection ◽  
Body Core ◽  
Heavy Work ◽  
Globe Temperature

Objective The aim of this study was to model the effect of body armor coverage on body core temperature elevation and wet-bulb globe temperature (WBGT) offset. Background Heat stress is a critical factor influencing the health and safety of military populations. Work duration limits can be imposed to mitigate the risk of exertional heat illness and are derived based on the environmental conditions (WBGT). Traditionally a 3°C offset to WBGT is recommended when wearing body armor; however, modern body armor systems provide a range of coverage options, which may influence thermal strain imposed on the wearer. Method The biophysical properties of four military clothing ensembles of increasing ballistic protection coverage were measured on a heated sweating manikin in accordance with standard international criteria. Body core temperature elevation during light, moderate, and heavy work was modeled in environmental conditions from 16°C to 34°C WBGT using the heat strain decision aid. Results Increasing ballistic protection resulted in shorter work durations to reach a critical core temperature limit of 38.5°C. Environmental conditions, armor coverage, and work intensity had a significant influence on WBGT offset. Conclusion Contrary to the traditional recommendation, the required WBGT offset was >3°C in temperate conditions (<27°C WBGT), particularly for moderate and heavy work. In contrast, a lower WBGT offset could be applied during light work and moderate work in low levels of coverage. Application Correct WBGT offsets are important for enabling adequate risk management strategies for mitigating risks of exertional heat illness.

A new empirical approach for predicting heat strain in workers exposed to hot indoor environments

2017 ◽  
Vol 27 (5) ◽  
pp. 597-605 ◽  
Author(s):  
Mohsen Aliabadi ◽  
Maryam Farhadian ◽  
Mahdi Jalali ◽  
Mohammad Jahangiri ◽  
Amir R. Negahban
Keyword(s):  
Neural Networks ◽  
Core Temperature ◽  
Heat Strain ◽  
Body Core Temperature ◽  
Indoor Environments ◽  
Proposed Model ◽  
Feed Forward Neural Networks ◽  
Body Core ◽  
Globe Temperature ◽  
Hot Environments

There is still a great need for a comprehensive index that could fully describe heat stress and, at the same time, provides a reliable correlation with the physiological responses of the human body. Using artificial neural networks, this study aims to present a new empirical model for predicting heat strain based on body core temperature in workers exposed to hot indoor environments. The study group consisted of 165 male workers working in heat treatment processes of metal industries in the central Iran. A predictive model was developed using eight parameters: age, metabolism rate, body mass index, body surface area, dry-bulb temperature, globe temperature, air velocity and relative humidity. The multilayer feed forward neural networks with different structures were developed using R 3.2.2 statistical software. The results showed that the mean square error of the core temperature predicted by the proposed model was 0.25℃. Based on the Garson algorithm, the dry-bulb and globe temperatures were found to be the most important factors that could affect the human heat strain. The proposed model can be a useful tool for occupational health professionals in analysing heat strain in hot environments.

scholarly journals Core Temperature Responses in Elite Cricket Players during Australian Summer Conditions

Sports ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 164
Author(s):  
Sharon Stay ◽  
Michelle Cort ◽  
David Ward ◽  
Alex Kountouris ◽  
John Orchard ◽  
...  
Keyword(s):  
Core Temperature ◽  
Air Temperature ◽  
Perceived Exertion ◽  
Wet Bulb Globe Temperature ◽  
Exertional Heat Illness ◽  
Increased Risk ◽  
Globe Temperature ◽  
Temperature Responses ◽  
Breaks In Play ◽  
Australian Summer

This study aimed to observe core temperature responses in elite cricket players under match conditions during the summer in Australia. Thirty-eight Australian male cricketers ingested capsule temperature sensors during six four-day first-class matches between February 2016 and March 2017. Core temperature (Tc) was recorded during breaks in play. Batters showed an increase in Tc related to time spent batting of approximately 1 °C per two hours of play (p < 0.001). Increases in rate of perceived exertion (RPE) in batters correlated with smaller elevations in Tc (0.2 °C per one unit of elevation in RPE) (p < 0.001). Significant, but clinically trivial, increases in Tc of batters were found related to the day of play, wet bulb globe temperature (WBGT), air temperature, and humidity. A trivial increase in Tc (p < 0.001) was associated with time in the field and RPE when fielding. There was no association between Tc and WBGT, air temperature, humidity, or day of play in fielders. This study demonstrates that batters have greater rises in Tc than other cricket participants, and may have an increased risk of exertional heat illness, despite exposure to similar environmental conditions.

The recommended Threshold Limit Values for heat exposure fail to maintain body core temperature within safe limits in older working adults

2017 ◽  
Vol 14 (9) ◽  
pp. 703-711 ◽  
Author(s):  
Dallon T. Lamarche ◽  
Robert D. Meade ◽  
Andrew W. D'Souza ◽  
Andreas D. Flouris ◽  
Stephen G. Hardcastle ◽  
...  
Keyword(s):  
Core Temperature ◽  
Heat Exposure ◽  
Body Core Temperature ◽  
Limit Values ◽  
Threshold Limit Values ◽  
Working Adults ◽  
Threshold Limit ◽  
Body Core ◽  
Safe Limits

Hypothalamic paraventricular nucleus is critical for renal vasoconstriction elicited by elevations in body temperature

2008 ◽  
Vol 294 (2) ◽  
pp. F309-F315 ◽  
Author(s):  
Joo Lee Cham ◽  
Emilio Badoer
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Renal Blood Flow ◽  
Core Temperature ◽  
Paraventricular Nucleus ◽  
Hypothalamic Paraventricular Nucleus ◽  
Body Core Temperature ◽  
Control Group ◽  
Body Core

Redistribution of blood from the viscera to the peripheral vasculature is the major cardiovascular response designed to restore thermoregulatory homeostasis after an elevation in body core temperature. In this study, we investigated the role of the hypothalamic paraventricular nucleus (PVN) in the reflex decrease in renal blood flow that is induced by hyperthermia, as this brain region is known to play a key role in renal function and may contribute to the central pathways underlying thermoregulatory responses. In anesthetized rats, blood pressure, heart rate, renal blood flow, and tail skin temperature were recorded in response to elevating body core temperature. In the control group, saline was microinjected bilaterally into the PVN; in the second group, muscimol (1 nmol in 100 nl per side) was microinjected to inhibit neuronal activity in the PVN; and in a third group, muscimol was microinjected outside the PVN. Compared with control, microinjection of muscimol into the PVN did not significantly affect the blood pressure or heart rate responses. However, the normal reflex reduction in renal blood flow observed in response to hyperthermia in the control group (∼70% from a resting level of 11.5 ml/min) was abolished by the microinjection of muscimol into the PVN (maximum reduction of 8% from a resting of 9.1 ml/min). This effect was specific to the PVN since microinjection of muscimol outside the PVN did not prevent the normal renal blood flow response. The data suggest that the PVN plays an essential role in the reflex decrease in renal blood flow elicited by hyperthermia.

MK801 impairs thermoregulation in the heat

2002 ◽  
Vol 80 (3) ◽  
pp. 226-232 ◽  
Author(s):  
Frédéric Canini ◽  
Nadine Simler ◽  
Lionel Bourdon
Keyword(s):  
Locomotor Activity ◽  
Nmda Receptor ◽  
Receptor Antagonist ◽  
Core Temperature ◽  
Exposure Duration ◽  
Heat Exposure ◽  
Nmda Receptor Antagonist ◽  
Dopamine Metabolism ◽  
Body Core Temperature ◽  
Body Core

The effects of MK801 (dizocilpine), a glutamate NMDA receptor antagonist, on thermoregulation in the heat were studied in awake rats exposed to 40°C ambient temperature until their body core temperature reached 43°C. Under these conditions, MK801-treated rats exhibited enhanced locomotor activity and a steady rise in body core temperature, which reduced the heat exposure duration required to reach 43°C. Since MK801-treated rats also showed increased striatal dopaminergic metabolism at thermoneutrality, the role of dopamine in the MK801-induced impairment of thermoregulation in the heat was determined using co-treatment with SCH23390, a dopamine D1 receptor antagonist. SCH23390 normalized the locomotor activity in the heat without any effect on the heat exposure duration. These results suggest that the MK801-induced impairment of thermoregulation in the heat is related to neither a dopamine metabolism alteration nor a locomotor activity enhancement.Key words: heatstroke, NMDA receptor, thermoregulation, dopamine, locomotion.

Body Fatness, Body Core Temperature, and Heat Loss During Moderate-Intensity Exercise

2013 ◽  
Vol 84 (11) ◽  
pp. 1153-1158 ◽  
Author(s):  
Jayme D. Limbaugh ◽  
Gregory S. Wimer ◽  
Lynn H. Long ◽  
William H. Baird
Keyword(s):  
Heat Loss ◽  
Core Temperature ◽  
Body Core Temperature ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Body Fatness ◽  
Body Core

scholarly journals Measuring body core temperature using a novel non-invasive sensor

2015 ◽  
Vol 4 (S1) ◽  
Author(s):  
Yoram Epstein ◽  
Savyon Mazgaoker ◽  
Doron Gruber ◽  
Daniel S Moran ◽  
Ran Yanovich ◽  
...  
Keyword(s):  
Core Temperature ◽  
Body Core Temperature ◽  
Non Invasive ◽  
Body Core

scholarly journals Identifying the need for locally-observed wet bulb globe temperature across outdoor athletic venues for current and future climates in a desert environment

2021 ◽  
Author(s):  
Haven Guyer ◽  
Matei Georgescu ◽  
David M Hondula ◽  
Floris Wardenaar ◽  
Jennifer Vanos
Keyword(s):  
Climate Projections ◽  
Design Strategies ◽  
Local Cooling ◽  
Wet Bulb Globe Temperature ◽  
Exertional Heat Illness ◽  
Cooling Design ◽  
Weather Stations ◽  
Globe Temperature ◽  
Sports Venues ◽  
Projected Changes

Abstract Exertional heat illness and stroke are serious concerns across youth and college sports programs. While some teams and governing bodies have adopted the wet bulb globe temperature (WBGT), few practitioners use measurements on the field of play; rather, they often rely on regionally modeled or estimated WBGT. However, urban development-induced heat and projected climate change increase exposure to heat. We examined WBGT levels between various athletic surfaces and regional weather stations under current and projected climates and in hot-humid and hot-dry weather regimes in the southwest U.S. in Tempe, Arizona. On-site sun-exposed WBGT data across five days (07:00–19:00 local time) in June (dry) and August (humid) were collected over five athletic surfaces: rubber, artificial turf, clay, grass, and asphalt. Weather stations data were used to estimate regional WBGT (via the Liljegren model) and compared to on-site, observed WBGT. Finally, projected changes to WBGT were modeled under mid-century and late-century conditions. On-field WBGT observations were, on average, significantly higher than WBGT estimated from regional weather stations by 2.4°C–2.5°C, with mean on-field WBGT across both months of 28.52.76°C (versus 25.83.21°C regionally). However, between-athletic surface WBGT differences were largely insignificant. Significantly higher mean WBGTs occurred in August (30.12.35°C) versus June (26.92.19°C) across all venues; August conditions reached ‘limit activity’ or ‘cancellation’ thresholds for 6–8 hours and 2–4 hours of the day, respectively, for all sports venues. Climate projections show increased WBGTs across measurement locations, dependent on projection and period, with average August WBGT under the highest representative concentration pathway causing all-day activity cancellations. Practitioners are encouraged to use WBGT devices within the vicinity of the fields of play, yet should not rely on weather station estimations without corrections used. Heat concerns are expected to increase in the future, underlining the need for athlete monitoring, local cooling design strategies, and heat adaptation for safety.

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