Biophysical modelling predicts unreliable core temperature responses on healthy older adults using electric fans at residential homes during heatwaves

Wang, Faming; Deng, Qihong; Lei, Tze‐Huan; Wang, Xingming; Wang, Alex Rui

doi:10.1016/j.buildenv.2022.109888

Cited by 8 publications

(2 citation statements)

References 13 publications

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“…Heat exposure characteristics unique to indoor settings may be more predictive of risk than more accessible outdoor parameters. Whether that be as a result of discrepancies between indoor-outdoor temperature and relative humidity [ 49 , 89–91 ], the observed cumulative and divergent rise in indoor temperatures over successive heat days [ 92 ], or the overnight indoor conditions being markedly higher than those outside [ 93 ].…”

Section: Discussionmentioning

confidence: 99%

Experimental research in environmentally induced hyperthermic older persons: A systematic quantitative literature review mapping the available evidence

et al. 2023

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The heat-related health burden is expected to persist and worsen in the coming years due to an aging global population and climate change. Defining the breadth and depth of our understanding of age-related changes in thermoregulation can identify underlying causes and strategies to protect vulnerable individuals from heat. We conducted the first systematic quantitative literature review to provide context to the historical experimental research of healthy older adults – compared to younger adults or unhealthy age matched cases – during exogenous heat strain, focusing on factors that influence thermoregulatory function (e.g. co-morbidities). We identified 4,455 articles, with 147 meeting eligibility criteria. Most studies were conducted in the US (39%), Canada (29%), or Japan (12%), with 71% of the 3,411 participants being male. About 71% of the studies compared younger and older adults, while 34% compared two groups of older adults with and without factors influencing thermoregulation. Key factors included age combined with another factor (23%), underlying biological mechanisms (18%), age independently (15%), influencing health conditions (15%), adaptation potential (12%), environmental conditions (9%), and therapeutic/pharmacological interventions (7%). Our results suggest that controlled experimental research should focus on the age-related changes in thermoregulation in the very old, females, those with overlooked chronic heat-sensitive health conditions (e.g. pulmonary, renal, mental disorders), the impact of multimorbidity, prolonged and cumulative effects of extreme heat, evidence-based policy of control measures (e.g. personal cooling strategies), pharmaceutical interactions, and interventions stimulating protective physiological adaptation. These controlled studies will inform the directions and use of limited resources in ecologically valid fieldwork studies.

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Section: Discussionmentioning

confidence: 99%

Experimental research in environmentally induced hyperthermic older persons: A systematic quantitative literature review mapping the available evidence

et al. 2023

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“…In addition to data requirements, there seems to be a need for improving the thermo-physiological modeling beyond the heat balance approach, as recent findings suggest that the simple models will underestimate physiological heat strain under electrical fan use, e.g., for the vulnerable elderly population [ 31 ].…”

Section: Introductionmentioning

confidence: 99%

Temperature–Humidity-Dependent Wind Effects on Physiological Heat Strain of Moderately Exercising Individuals Reproduced by the Universal Thermal Climate Index (UTCI)

Bröde

Kampmann

2023

Biology

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Increasing wind speed alleviates physiological heat strain; however, health policies have advised against using ventilators or fans under heat wave conditions with air temperatures above the typical skin temperature of 35 °C. Recent research, mostly with sedentary participants, suggests mitigating the effects of wind at even higher temperatures, depending on the humidity level. Our study aimed at exploring and quantifying whether such results are transferable to moderate exercise levels, and whether the Universal Thermal Climate Index (UTCI) reproduces those effects. We measured heart rates, core and skin temperatures, and sweat rates in 198 laboratory experiments completed by five young, semi-nude, heat-acclimated, moderately exercising males walking the treadmill at 4 km/h on the level for three hours under widely varying temperature–humidity combinations and two wind conditions. We quantified the cooling effect of increasing the wind speed from 0.3 to 2 m/s by fitting generalized additive models predicting the physiological heat stress responses depending on ambient temperature, humidity, and wind speed. We then compared the observed wind effects to the assessment performed by the UTCI. Increasing the wind speed lowered the physiological heat strain for air temperatures below 35 °C, but also for higher temperatures with humidity levels above 2 kPa water vapor pressure concerning heart rate and core temperature, and 3 kPa concerning skin temperature and sweat rate, respectively. The UTCI assessment of wind effects correlated positively with the observed changes in physiological responses, showing the closest agreement (r = 0.9) for skin temperature and sweat rate, where wind is known for elevating the relevant convective and evaporative heat transfer. These results demonstrate the potential of the UTCI for adequately assessing sustainable strategies for heat stress mitigation involving fans or ventilators, depending on temperature and humidity, for moderately exercising individuals.

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Risk of heatstroke in healthy elderly during heatwaves: A thermoregulatory modeling study

Wang

Zhao

et al. 2023

Building and Environment

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Biophysical modelling predicts unreliable core temperature responses on healthy older adults using electric fans at residential homes during heatwaves

Cited by 8 publications

References 13 publications

Experimental research in environmentally induced hyperthermic older persons: A systematic quantitative literature review mapping the available evidence

Experimental research in environmentally induced hyperthermic older persons: A systematic quantitative literature review mapping the available evidence

Temperature–Humidity-Dependent Wind Effects on Physiological Heat Strain of Moderately Exercising Individuals Reproduced by the Universal Thermal Climate Index (UTCI)

Risk of heatstroke in healthy elderly during heatwaves: A thermoregulatory modeling study

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