Health Risks and Interventions in Exertional Heat Stress

Abstract

Background: With climate change, heat waves are expected to become more frequent in the near future. Already, on average more than 25 000 "heat deaths" are estimated to occur in Europe every year. However, heat stress and heat illnesses arise not just when ambient temperatures are high. Physical exertion increases heat production within the organism many times over; if not enough heat is lost, there is a risk of exertional heat stress. This review article discusses contributing factors, at-risk groups, and the diagnosis and treatment of heat illnesses. Methods: A selective literature search was carried out on PubMed. Current guidelines and expert recommendations were also included. Results: Apart from muscular heat production (>70% of converted energy), there are other factors that singly or in combination can give rise to heat stress: clothing, climate/acclimatization, and individual factors. Through its insulating properties, clothing reduces the evaporation of sweat (the most effective physiological cooling mechanism). A sudden heat wave, or changing the climate zone (as with air travel), increases the risk of a heat-related health event. Overweight, low fitness level, acute infections, illness, dehydration, and other factors also reduce heat tolerance. In addition to children, older people are particularly at risk because of their reduced physiological adaptability, (multi-)morbidity, and intake of prescription drugs. A heat illness can progress suddenly to life-threatening heat stroke. Successful treatment depends on rapid diagnosis and cooling the body down as quickly as possible. The aim is to reduce core body temperature to <40 °C within 30 minutes. Conclusion: Immediately effective cooling interventions are the only causal treatment for heat stroke. Time once lost cannot be made up. Prevention (acclimatiza tion, reduced exposure, etc.) and terminating the heat stress in good time (e.g., stopping work) are better than any cure.

Epidemiology of Exertional Heat Illness in the Military: A Systematic Review of Observational Studies

“…This finding echoes previously documented literature that higher BMI (indicating higher body fat) increases risk of EHI [ 69 ]. In obese individuals, factors such as increased metabolic heat production during exercise, lower surface to mass ratio, and the insulating effect of subcutaneous adipose tissue may cause an increase in core body temperature and without adequate dissipation, may result in EHI [ 16 , 70 , 71 ]. In addition, evidence suggests that obese soldiers are less physically fit, as evidenced by failing the fitness test compared to non-obese soldiers [ 72 ].…”

“…During exercise in the heat, the mechanism of heat loss is via cutaneous vasodilation and evaporation of sweat [ 15 ]. As core temperature rises with continuous exertion and metabolic heat production, the physiological cooling mechanism of heat loss through evaporation of sweat may impeded by the protective clothing increasing the risk of EHI [ 16 , 17 ]. Furthermore, evidence suggests that high levels of motivation to push through the heat strain and beyond physiological limits without self-pacing also increases the risk of EHI [ 3 , 18 ].…”

Health effects of heating, ventilation and air conditioning on hospital patients: a scoping review

“…The current knowledge of HVAC related effects is based on studies on health issues in office workers [17] or on exercise-related heat illness [18,19]. Climatic influences on the physiology were tested with volunteers in climatic chambers [20,21].…”

Tod bei der Arbeit – eine Analyse tödlicher Arbeitsunfälle von 2005 bis 2016 im Obduktionsgut des Instituts für Rechtsmedizin in Frankfurt am Main

“…Zudem beeinträchtigen die erhöhten Temperaturen zur Sommerzeit die Arbeiter in ihrer Aufmerksamkeit und können zu einer frühzeitigen Ermüdung führen [1]. Das Einhalten regelmäßiger Pausenzeiten, die Anpassung der Bekleidung an das Umgebungsklima [20] und die Ausführung risikoreicher, körperlich anstrengender Arbeiten zu klimatisch günstigen Jahres-und Tageszeiten helfen, der Erschöpfung der Arbeiter entgegenzuwirken. Diese Präventionsmaßnahmen könnten vor dem Hintergrund des Klimawandels zukünftig noch an Bedeutung zunehmen.…”