Heat Balance When Climbing Mount Everest

Background: Mountaineers must control and regulate their thermal comfort and heat balance to survive the rigors of high altitude environment. High altitudes feature low air pressure and temperatures, strong winds and intense solar radiation, key factors affecting an expedition’s success. All these c...

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Autores principales:	Robert K. Szymczak, Krzysztof Błażejczyk
Formato:	article
Lenguaje:	EN
Publicado:	Frontiers Media S.A. 2021
Materias:	heat balance thermal stress mountain bioclimate altitude extremes mountaineering Physiology QP1-981
Acceso en línea:	https://doaj.org/article/98a39dcb5596444881a297f94aaa47db
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spelling	oai:doaj.org-article:98a39dcb5596444881a297f94aaa47db2021-12-01T01:41:50ZHeat Balance When Climbing Mount Everest1664-042X10.3389/fphys.2021.765631https://doaj.org/article/98a39dcb5596444881a297f94aaa47db2021-11-01T00:00:00Zhttps://www.frontiersin.org/articles/10.3389/fphys.2021.765631/fullhttps://doaj.org/toc/1664-042XBackground: Mountaineers must control and regulate their thermal comfort and heat balance to survive the rigors of high altitude environment. High altitudes feature low air pressure and temperatures, strong winds and intense solar radiation, key factors affecting an expedition’s success. All these climatic elements stress human heat balance and survival. We assess components of human heat balance while climbing Mt. Everest.Materials and Methods: We calculated climbers’ heat balance using the Man-ENvironment heat EXchange model (MENEX-2005) and derived meteorological data from the National Geographic Expedition’s in situ dataset. Three weather stations sited between 3810 and 7945 m a.s.l. provided data with hourly resolution. We used data for summer (1 May–15 August 2019) and winter (16 October 2019–6 January 2020) seasons to analyze heat balance elements of convection, evaporation, respiration and radiation (solar and thermal).Results: Meteorological and other factors affecting physiology—such as clothing insulation of 3.5–5.5 clo and activity levels of 3–5 MET—regulate human heat balance. Elevation above sea level is the main element affecting heat balance. In summer two to three times more solar radiation can be absorbed at the summit of the mountain than at the foot. Low air pressure reduces air density, which reduces convective heat loss at high altitude by up to half of the loss at lower locations with the same wind speed and air temperature.Conclusion: 1. Alpinists face little risk of overheating or overcooling while actively climbing Mt. Everest, despite the potential risk of overcooling at extreme altitudes on Mt. Everest in winter. 2. Convection and evaporation are responsible for most of the heat lost at altitude. 3. Levels of physical activity and clothing insulation play the greatest role in counteracting heat loss at high altitude.Robert K. SzymczakKrzysztof BłażejczykFrontiers Media S.A.articleheat balancethermal stressmountain bioclimatealtitudeextremesmountaineeringPhysiologyQP1-981ENFrontiers in Physiology, Vol 12 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	heat balance thermal stress mountain bioclimate altitude extremes mountaineering Physiology QP1-981
spellingShingle	heat balance thermal stress mountain bioclimate altitude extremes mountaineering Physiology QP1-981 Robert K. Szymczak Krzysztof Błażejczyk Heat Balance When Climbing Mount Everest
description	Background: Mountaineers must control and regulate their thermal comfort and heat balance to survive the rigors of high altitude environment. High altitudes feature low air pressure and temperatures, strong winds and intense solar radiation, key factors affecting an expedition’s success. All these climatic elements stress human heat balance and survival. We assess components of human heat balance while climbing Mt. Everest.Materials and Methods: We calculated climbers’ heat balance using the Man-ENvironment heat EXchange model (MENEX-2005) and derived meteorological data from the National Geographic Expedition’s in situ dataset. Three weather stations sited between 3810 and 7945 m a.s.l. provided data with hourly resolution. We used data for summer (1 May–15 August 2019) and winter (16 October 2019–6 January 2020) seasons to analyze heat balance elements of convection, evaporation, respiration and radiation (solar and thermal).Results: Meteorological and other factors affecting physiology—such as clothing insulation of 3.5–5.5 clo and activity levels of 3–5 MET—regulate human heat balance. Elevation above sea level is the main element affecting heat balance. In summer two to three times more solar radiation can be absorbed at the summit of the mountain than at the foot. Low air pressure reduces air density, which reduces convective heat loss at high altitude by up to half of the loss at lower locations with the same wind speed and air temperature.Conclusion: 1. Alpinists face little risk of overheating or overcooling while actively climbing Mt. Everest, despite the potential risk of overcooling at extreme altitudes on Mt. Everest in winter. 2. Convection and evaporation are responsible for most of the heat lost at altitude. 3. Levels of physical activity and clothing insulation play the greatest role in counteracting heat loss at high altitude.
format	article
author	Robert K. Szymczak Krzysztof Błażejczyk
author_facet	Robert K. Szymczak Krzysztof Błażejczyk
author_sort	Robert K. Szymczak
title	Heat Balance When Climbing Mount Everest
title_short	Heat Balance When Climbing Mount Everest
title_full	Heat Balance When Climbing Mount Everest
title_fullStr	Heat Balance When Climbing Mount Everest
title_full_unstemmed	Heat Balance When Climbing Mount Everest
title_sort	heat balance when climbing mount everest
publisher	Frontiers Media S.A.
publishDate	2021
url	https://doaj.org/article/98a39dcb5596444881a297f94aaa47db
work_keys_str_mv	AT robertkszymczak heatbalancewhenclimbingmounteverest AT krzysztofbłazejczyk heatbalancewhenclimbingmounteverest
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Heat Balance When Climbing Mount Everest

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