In almost ten years, around thirty thousand people have died in the summer in France because of the heat, according to health authorities. And these deaths are far from being confined to periods of heat waves, which are certainly very deadly. “There is a very significant impact of heat on mortality in France during the summer”, summed up Friday June 23, during a press conference, Guillaume Boulanger, researcher at the French public health agency.
“This specifically concerns periods of heat waves but also all other days when the population is exposed to high heat”, detailed Guillaume Boulanger, presenting a study that he supervised for the agency.
According to this work, between 30,000 and 35,000 deaths in total are attributable to heat in France during the summers of 2014-2022, in a context marked by an increase in heat waves against a background of global warming. This work illustrates for the first time the weight of exposure to heat in mortality in France, and its spatial and temporal evolution.
Acceleration of heat waves
These figures are published as summer temperatures have settled in France since the end of May. Météo France forecasts for June to August temperatures probably above normal.
More broadly, recent research confirms that global warming is particularly rapid in Europe, contributing to an acceleration of heat waves. What is new, in this context, in the latest estimates from Public Health France? The deadly effects of heat waves are well known. Thus, Public Health France has already estimated that nearly 3,000 excess deaths had been recorded during the three heat waves of the summer of 2022, which were particularly hot.
But these figures do not distinguish other causes such as waves of Covid. And above all, they only concern heat waves, that is to say the few days when the heat reached particularly high peaks without a lull at night.
The work published this Friday has a broader aim: to assess the mortality associated with all periods of heat, which affect people’s health even when they are not intense.
Not just the older ones
However, the authorities are currently focusing their communication and their health measures on periods of heat waves, in particular since the awareness linked to the particularly deadly heat wave of 2003: 15,000 deaths estimated, especially among the elderly.
For researchers from Public Health France, this is not enough. Certainly, it is particularly necessary to monitor heat waves, which cause many deaths in a short time, but it is also necessary to see wider.
“This focus on heat waves tends […] to underestimate the total impact of heat on health, and in particular on mortality”, warns the study. “Heat is one of the most worrying environmental risks in Europe”, according to Public Health France.
Thus, according to researchers’ estimates, nearly three-quarters of heat-related deaths occurred outside of heat waves. To reach these conclusions, the study uses complex and difficult-to-summarize models. Not only do they compare the evolution of temperatures and mortality, but they also seek to distinguish other causes, in particular the Covid pandemic.
These figures therefore only constitute an estimate, the precise level of which depends on certain methodological choices. What is a heat spell, for example? Here, it is half of the hottest days observed over the period studied. However, these estimates make it possible to give an order of magnitude of certain phenomena, such as the effects of heat on health outside the heat wave.
They also make it possible to emphasize that the elderly are not the only ones at risk, even if they are by far the first victims of the heat. “Heat waves are the extreme climatic events that have the greatest impact on health, on all age groups. […] The deaths particularly concern the elderly (over 75), but a third of the deaths concern the rest of the population”, underlined Guillaume Boulanger. “Exposure to heat causes deaths within the entire population” , he insisted.