Last summer, 62 thousand people died from the heat in Europe

Last summer was the hottest on record in Europe. The EU statistics agency Eurostat had already reported excess deaths linked to this unusual weather episode, but the extent had not yet been estimated. This was done thanks to the joint work of researchers from Inserm and the Barcelona Institute for Global Health (ISGlobal), which has just been published Nature Medicine:.

According to their calculations, high temperatures (+ 2.3°C above seasonal norms, average 20.3°C) in the summer of 2022 caused 61,672 deaths on the European continent between May 30 and September 4. In the summer of 2003, with an average temperature during the season of 20.2 °C, the excess mortality was 71,449 deaths. It was this health disaster that made people realize the urgency of protecting the population by planning strategies to adapt the environment, especially the urban one, to increasing temperatures, as well as developing an ongoing plan for heat waves. Every year from June to mid-September. vigilance maps and communication campaigns. Last summer, text messages were sent for the first time on a large-scale pilot basis to heat-vulnerable populations during yellow and orange alerts. A program whose effectiveness must be evaluated.

However, the figures of 2003 and 2022 are not strictly comparable, the authors warn. on the one hand, they state that “excess mortality” is the difference between the observed mortality and the expected mortality for the season, and “ because heat-related mortality occurs every summer, the excess mortality estimate may exclude the burden of heat-related mortality. “. On the other hand, the perimeter studied in 2003 included only 16 countries, while the perimeter chosen by the researchers for 2022 includes 35 (European Union, Iceland, Serbia, Montenegro, Albania, Norway, United Kingdom, Liechtenstein and Switzerland). “ Restricted to the same regions and countries, our estimates of heat deaths for the summer of 2022 were 15 lower. % (ie 52 121: death). »

To make their calculations, the researchers relied on temperature and mortality data from 2015 to 2022 for a target population of 543 million inhabitants. From this, they derived models that allowed them to estimate regionally the mortality attributable to high summer temperatures each week. For the summer of 2022, although above-normal temperatures were observed throughout the period, most deaths (38,881) occurred between July 11 and August 14 due to very hot weather.

France, the country with the highest increase in temperature compared to seasonal averages (+2.43°C), had the fourth highest death toll, with a total of 4,807 heat deaths. It is followed by Italy (18,010), Spain (11,324) and Germany (8,173). On the other hand, if we consider the death rate per million inhabitants, Italy, Greece, Spain and Portugal were the most affected, with 295, 280, 237 and 211 deaths respectively. France fares much better in this regard, with 73 deaths per million inhabitants, below the European average of an estimated 116.

Reduce the vulnerability of the population

“ Excess mortality is related to both population vulnerability and the temperature attained », explains Inserm researcher Hicham Achebak, who led the research. Age range, health status, standard of living and quality of housing (insulation, air conditioning or not, etc.) are all factors that can increase the risk of heatstroke death. On the other hand, measures adopted since 2003, such as heat wave plans or increased green spaces, can partially counteract this effect. “ In terms of adaptation to the heat, the study teaches us that France is doing quite well, even if there is still progress, because there are still a few thousand deaths that must be regretted. », Hicham Achebak analyzes. The countries of the South, which suffered proportionally more than France last summer, face structural difficulties in addition to the felt temperature: lower socio-economic levels, poorly insulated housing, etc.

Public Health France (SPF) presented its own mortality estimates for the summer of 2022. However, the calculations focused on episodes of heat waves that correspond to a strictly scientific definition: at least three consecutive days when average daytime and nighttime temperatures exceed certain thresholds that vary by region. People over 75 make up the majority of victims, and the four southern regions account for almost two-thirds of the deaths: Occitania, Auvergne-Rhône-Alpes, Nouvelle-Aquitaine and Provence-Alpes-Côte d’Azur. The SPF recently presented a mortality simulation imputed to all summers since 2014 (and not just heatwave periods) and arrived at 6,969 heat-related deaths in France for 2022.