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), mainland departments were placed under a red alert due to exceptionally high daytime temperatures.

In Occitanie, these two heatwave episodes caused alert thresholds to be exceeded in 7 departments during the first episode in June–July and in 7 departments during the second episode (10 departments affected across the two episodes). On this occasion, the departments of Gard and Hérault were placed under a red alert (for two consecutive days) for the first time since the PNC was implemented. 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, 56 [-21:126] excess deaths were estimated, representing a relative excess mortality of +3.7% [-1.3:8.7]. Of these excess deaths, 17 were observed during the first heatwave episode (mostly among people aged 45–64) and 39 during the second episode (mostly among people aged 75 and older).

• Heat-related conditions (defined by the iCanicule indicator, which includes hyperthermia, dehydration, and hyponatremia) accounted for up to 1.5% of emergency department visits during the first heatwave and up to 4.4% of SOS Médecins calls during the second heatwave. The hospitalization rate following an emergency department visit for the iCanicule indicator during these two episodes was 45% and 51%, respectively, across all age groups. While the impact was greater among those aged 75 and older, all age groups were affected.

The health impacts of heat observed in this study were not limited to these periods alone, as two-thirds of emergency department visits and two-thirds of SOS Médecins calls occurred outside of these two heat waves.