Key Points

The summer of 2017 was warmer than normal and marked by a succession of two peaks and four heat waves, two of which were particularly notable:

• a widespread and early heat wave from June 17 to 24, 2017. Ninety departments were placed under a yellow or orange heat wave alert, and 96% of the metropolitan population was affected. This heat wave presented new exposure scenarios in school settings.

• a very intense heat wave, localized in the South, from July 31 to August 7, 2017. 23% of the metropolitan population was affected by this heat wave, which was marked by very high nighttime temperatures.

Nine departments were placed under an orange heat wave alert for the first time since the national heat wave plan was implemented in 2004.

These findings confirm the existence of excess mortality during heatwaves in France, which was more pronounced during the two heatwaves considered a priori the most dangerous. Over all periods when thresholds were exceeded, 474 excess deaths were observed, representing a 5% increase in mortality compared to the same periods in previous years. The heat wave from June 17 to 24 resulted in 345 excess deaths (+7%), and the one from July 31 to August 7 resulted in 143 excess deaths (+7%). While the elderly constitute the largest group among the deaths, signs of increased mortality are observed in other age groups as well.

Heat intensity—i.e., the deviation from typical temperatures for the region—appears to remain a good indicator of the severity of the impact.

Ten workplace deaths potentially linked to heat were reported during the summer, including seven that occurred during the heat wave from June 17 to 24. This indicator provides only a partial estimate of the full range of potential impacts on workers.

Heat also affects healthcare utilization; in total, 8,000 emergency room visits and 2,760 SOS Médecins consultations for heat-related conditions were recorded during heat peaks and heat waves. During the June heat wave, heat-related illnesses accounted for more than 4% of total emergency room visits and SOS Médecins consultations among those aged 75 and older.

All age groups are affected, with a notably high proportion of people under 75 seeking medical care for heat-related illnesses during the June 2017 heat wave. Those aged 75 and older remain the most affected age group.

Ahead of the summer, 500,000 documents outlining preventive measures were distributed nationwide. During heat waves, communication efforts were intensified through radio and TV spots, as well as poster campaigns.

Despite the preventive measures put in place, significant health impacts continue to be observed in metropolitan France during periods of high heat. The onset of a heat wave as early as mid-June prompts the development of preventive measures for schools.