Key Points

In mainland France, June and July 2019 were marked by two widespread and intense heat waves. During these two heat waves, and for the first time since the implementation of the National Heat Wave Plan (PNC), mainland departments were placed on red alert due to exceptionally high daytime temperatures.

In the Île-de-France region, these two heatwave episodes caused alert thresholds to be exceeded in four Île-de-France departments (Paris and its inner suburbs) during the first episode in June and across the entire region during the second episode. On this occasion, all eight departments were placed under a red alert for two consecutive days for the first time. A significant impact on health was observed during these periods:

• The two periods during which alert thresholds were exceeded were associated with a total of 368 [300–431] excess deaths in the affected departments of the region, representing a relative excess mortality rate of +16.2%. During the more intense heatwave in July, the Île-de-France region recorded a total of 319 excess deaths. People aged 75 and older accounted for the majority of excess deaths (264 deaths) during both episodes.

• During the first episode, consultations for heat-related conditions (defined by the iCanicule indicator, which includes hyperthermia, dehydration, and hyponatremia) accounted for 396 visits to hospital emergency departments (0.7% of total activity) and 213 cases handled by SOS Médecins (1.7% of total activity). During the second episode, activity in hospital emergency departments was similar to that of the first episode (423 visits for iCanicule, or 0.7% of total activity), while activity at SOS Médecins was lower (136 cases for iCanicule, or 1.0% of activity). The hospitalization rates following emergency department visits for iCanicule during these two episodes were 41% and 51%, respectively. While the impact was greater among those aged 75 and older, all age groups were affected.

The health impacts of heat observed here were not limited to these periods alone, as 60% of emergency department visits and 41% of SOS Médecins procedures for the iCanicule indicator occurred outside of these two heat waves.