2023-08-29 05:40:09
A woman takes a nap in front of a fan, in Montaigu (Vendée), August 21, 2023. MATHIEU THOMASSET / HANS LUCAS VIA AFP
In many countries, particularly in Europe, deaths during heat waves are higher among women than among men. A gap that some researchers have tried to explain, and which would result not only from the fact that women live longer, but also from physiological and behavioral factors. During the 2003 heat wave in France, the number of heat-related deaths among the over 55s was 15% higher among women than among men at the same age, according to a study published by several researchers from the National Institute of Health and Medical Research (Inserm) in 2006.
France is far from being an exception. Several studies conducted in the Netherlands also show significant differences in the number of deaths during heat waves by gender. In one of the most comprehensive studies conducted on the subject, published in 2021, researchers at the Free University of Amsterdam (Vrije Universiteit) have identified several possible causes, such as differences in sweating, cardiovascular strain, body surface area to mass ratio, and women’s greater propensity to live alone or be active in the home. Since women live longer (up to 81 years in Europe, compared to 75 years for men) and are therefore over-represented among the elderly vulnerable to heat, the researchers adjusted their results so as not to overestimate female mortality.
First explanation put forward by the researchers: women sweat less and therefore evacuate less heat. “Sweating is a particularly effective method of cooling and in this sense women, who have a lower capacity for perspiration and evaporation of sweat, are at a disadvantage”observes Hein Daanen, physiology researcher at the Free University of Amsterdam and co-author of this study. “Now, when the temperature of the air exceeds the body temperature [comprise en moyenne entre 36 °C et 37 °C]the only way for the body to lose heat is through perspiration”says Mike Tipton, researcher at the University of Portsmouth and author of several studies on the subject.
Size and weight differences
But that’s not all: as they better regulate their body temperature by increasing blood transfers to the skin, women are also more likely to develop cardiovascular problems during heat waves. “When it’s very hot, there is a kind of diversion effect, because the blood, which circulates more towards the skin, cannot go as much towards other parts of the body, such as, for example, the heart. . As the heart receives less blood, it compensates for this by beating faster, which raises cardiovascular pressure, which is already higher in women than in men, and increases the associated risks, such as strokes.explained Hein Daanen.
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