How many people did this summer's heatwave kill here in France? A report on the number of daily deaths published by France's statistics agency, the Institut National de la Statistique et des Études Économiques (INSEE), shows that there was a significant number of excess deaths across the country during June, July and August.
In the period from July 1st to August 22nd, for example, the number of deaths in 2022 was greater that both 2021 (+5.2%) and 2020 (+7.3%) and considerably higher than the average for the period 2015-2019 (+10.9%).
Graphic above: Some 138,522 people died from July 1st to August 22nd 2022, which is up on 2021 (+5.2%) and 2020 (+7.3%) and considerably higher that the average for the period 2015-2019 (+10.9%).
But not all of these people died because of the heat. The death notifications collected by town halls show the immediate cause of death and these very rarely highlight excessive temperatures themselves.
To find out how many individuals died from the heat one has instead to carry out a statistical investigation and make comparisons over several years. INSEE has begun working on this and has published its provisional assessment for deaths this summer. It will probably be revised upwards on September 30th with data from the end of August and after adjustments for the previous weeks. Meanwhile the official public health body Santé Publique France will produce a summary report on the issue in October (its report from 2021 is here).
According to this preliminary data, 1,748 people died every day on average in France in July, and 1,643 a day between August 1st and 22nd. If one compares that with the summer of 2019 – before the Covid pandemic – then the total number of excess deaths between June 1st and August 22nd is 11,124. All these figures are on the INSEE site.
But can one consider these 11,000-plus people to be victims of the heatwave, while over the same period some 5,290 people died with Covid-19 in France?
“The level of deaths in the summer of 2022 is clearly high in relation to 2019 when there was also a heatwave,” explained Sylvie Le Minez, head of the demographic and social studies unit at INSEE. “There are excess deaths and in all probability they are due in part to the heatwave. But to go from there to give a precise figure on the number of deaths caused by the heatwave, INSEE isn't going that far.”
Mediapart has compared the number of daily deaths with the numbers of départements or counties that were placed under orange or red heatwave alert over the summer. This shows that the peaks in mortality correspond with the peaks in temperatures.
Graphic above: The three heatwaves in the summer of 2022 gave rise to peaks of mortality. With 2,098 deaths, July 19th was the deadliest day. Just before then 83 départements or counties had been put on heatwave alert, a record for this summer.
Looking at the detailed figures, an initial peak of deaths appeared around June 18th. Across the whole of June 2022 the number of deaths was up by 4% compared with the same month in 2019, INSEE says. And in July the number of deaths from all causes reached a very clear peak on July 19th, after a less pronounced peak on July 12th, according to the agency.
Its experts, however, advise caution about making a direct comparison between years as the number of older people is greater in 2022 than in 2019. To measure the impact of the heatwave precisely one has to compare the number of deaths in 2022 to the number of deaths that would have been expected after taking into account the ageing of the population. This was the also method used to count Covid victims.
The initial figures from this comparison suggest a major number of excess deaths in the summer of 2022 in France, prompting reminders of the tragic heatwave of 2003. In that year 15,300 people lost their lives as a result of extreme temperatures; this was the excess mortality reported by INSEE at the time, after comparing it with the average number of deaths during the same period between 1999 and 2002.
Over the last 20 years the Covid-19 pandemic of 2020 is the only event in mainland France to have killed more than the 2003 heatwave, with 27,000 excess deaths recorded between March 10th and May 8th 2020.
The devastating effect of the heat on the death rate
Behind each death statistic there is, of course, a real person. They are our neighbours, elderly people, a worker exhausted on a worksite in extreme temperatures, a homeless person who has nowhere to get a drink and to get cool, a woman or man weakened by a heart problem or by advanced cancer. People can die from many causes during a heatwave.
“We know that heat kills. As soon as there are hot days, above the optimal temperature which is close to 20°C in our country, there is an increase in mortality from the main causes of death,” explained Rémy Slama, an environmental epidemiologist and co-author of a recent study in France into the impact of high temperatures on the causes of death over the last 50 years.
The researchers involved in the study have shown how from the moment temperatures pass the 20°C mark the number of deaths increases, from all causes. When the level of temperatures becomes extreme the effects are even more pronounced.
“That can be explained by several mechanisms: one is that when it's hot the cardiac system operates flat out and can produce signs of exhaustion in particular,” said Rémy Slama. “You die from the condition from which you were already suffering if you are frail: cardiovascular or respiratory disease, cancer, kidney failure, diabetes etc. Blood clotting can also increase, with possible cardio-respiratory effects.”
According to their study, this link with temperature also covers illnesses of the nervous system and endocrine disorders, mental illness and suicides. In the case of suicides, the explanation could come from a reduction in the level of serotonin, a neurotransmitter in the brain that performs the role of inhibiting impulsive behaviour when it gets hotter. Another theory is the reduced number of social contacts that people have during a heatwave.
These researchers did not specifically look at the 2022 heatwave in France. But given the scientific consensus on the impact of heat on mortality “it's inevitable that the heatwave had an impact,” said Rémy Slama.
Social factors also play a major role. In 2003 two thirds of the extra deaths were of women, according to INSEE. It said: “[A heatwave] in fact principally affects the most elderly, and women are over-represented in these ages.” The greatest level of excess deaths was in the Paris region and the Centre-Val de Loire region in central France.
In 2022 the level of excess deaths was not spread evenly across mainland France. In June 2022, for example, the mortality rate was more than 15% higher than the corresponding month in 2019 across four regions: Nouvelle-Aquitaine (+17%) in the south west, Provence-Alpes-Côte d’Azur (+18%) in the south, Pays de la Loire (+19%) in the centre west and Occitanie (+19%) in the south.
Mediapart has assembled geographical data showing the difference in the number of deaths by département compared with 2019. We excluded overseas départements and territories because there was no heatwave there and the mortality rate due to Covid-19 was also much greater there than in mainland France.
Graphic above: Comparing 2019 and 2022, the total number of deaths in the summer is up in 86 of the 96 mainland départements - especially in the south west of the country. This graphic shows the difference in the number of deaths from June 1st to August 22nd 2022 in relation to deaths in the same period in 2019, in other words before the Covid pandemic.
In France one in seven people live today in a territory that will be exposed to more than 20 abnormally hot summer days in the decades to come, according to another study by INSEE. The regions most affected will be Auvergne-Rhône-Alpes in the south east, Occitanie in the south and Bourgogne-Franche-Comté in the east.
In the areas most exposed to extreme heat some 1.2 million people currently live below the poverty line. They are particularly vulnerable to heatwaves because of the poor standard of their housing, their vulnerable health and in many cases their social isolation. In 2003 the deprived Seine-Saint-Denis département bordering Paris was one of the areas worst affected by excess deaths. Construction and agricultural workers are also at risk when temperatures reach extreme levels.
The figures published by INSEE, which are based on death notifications sent to town halls, also give one other important piece of information: the place where those people lost their lives in the summer of 2022. From this we can see that 27.7% died at home, an increase of 4.5 percentage points compared with the same period in 2019.
Mediapart turned these figures into a graphic (see below). The hospital, whether public or private, remains the main place of death, ahead of at home, in retirement and care homes, and finally on the street.
Graphic above: Between June 1st and August 22nd 2022 some 27.7% died at home, an increase of more than 4 percentage points compared with the same period in 2018 or 2019.
The significant number of deaths at home might in part explain the relative invisibility of these deaths. This underlines the importance of compiling and analysing data on the issue.
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- The original French version of this article can be found here.
English version by Michael Streeter