Key Points

In mainland France, June and July 2019 were marked by two widespread and intense heat waves. During these two heat waves, for the first time since the implementation of the National Heat Wave Plan (PNC), metropolitan departments were placed under a red alert due to exceptionally high daytime temperatures. Although the ARA region was affected by both episodes of exceptional intensity, no department in the region was placed under a red alert.

In Auvergne-Rhône-Alpes, these two heatwave episodes resulted in alert thresholds being exceeded for nine departments in the region during the first episode in June and for the entire region during the second episode. A significant impact on health was observed during these periods:

• During the periods when alert thresholds were exceeded and for the affected departments in the region, 239 [105–376] excess deaths were estimated, representing a relative excess mortality of +8%. Although the July heatwave was more intense, the June heatwave resulted in the highest number of deaths, with 160 deaths. While those aged 75 and older accounted for the majority of excess deaths (162 deaths) during both episodes, those aged 15–44 had the highest relative mortality rate.

• Heat-related conditions (defined by the iCanicule indicator, which includes hyperthermia, dehydration, and hyponatremia) accounted for up to 2% of emergency room visits and 4.7% of SOS Médecins calls during the first episode. During the second episode, this activity was lower, accounting for 1.2% of emergency room visits and 2.9% of SOS Médecins interventions. The hospitalization rate following an emergency room visit during these two episodes was 58.1% and 62.7%, respectively. While the impact was greater among those aged 75 and older, all age groups were affected.

Outside of these extreme periods, heat has a significant impact on health, as half of the emergency room visits for the iCanicule indicator occurred outside of heatwave episodes.

These results highlight the need to proactively address the prevention of heat-related impacts throughout the entire summer season and to intensify these efforts during heat waves, by identifying the most appropriate messages for the entire population.