The cloud, in particular loaded with sulfur dioxide and which formed following the eruption of the Cumbre Vieja volcano in the Canary Islands, arrived this Friday at noon above France.
In recent days, he had traveled back to Europe via northwest Africa and the Maghreb.
"The cloud is flying over part of the south of France, Corsica in particular", confirms Patrick Allard, CNRS research director emeritus at the Paris Institute of Globe Physics (IPGP) and president of the international association of volcanology.
The south and east of the country will be the most affected until the gradual evacuation of this cloud on Sunday.
Potentially, sulfur dioxide can cause respiratory or eye irritation.
But in this case, given the low density of the particles and the altitude of the cloud, the health risks for the French are almost non-existent.
Rains a little more acidic than usual, but without health or environmental consequences, could however be observed due to thunderstorms expected on Saturday in the territory.
In the Canaries, one of the two lava flows of the Cumbre Vieja volcano, which erupted on Sunday on the Spanish island of La Palma in the Canary archipelago, has stopped advancing, authorities announced Thursday evening.
The other flow, whose width reaches 500 m, "continues to progress, but much more slowly than before" in particular because of the topography, she added before stressing that the flows should not reach in the 'immediate ocean, "neither today nor tomorrow", Friday.
The authorities fear the arrival of lava in the sea because of the emission of toxic gases that it could cause.
According to the latest data from Copernicus, the European system of geospatial measurements, lava has so far destroyed 350 buildings and covered 166.2 ha - or 30 buildings and 12 ha more than the day before - on the island whose main activity economic is the cultivation of bananas.
The eruption of Cumbre Vieja, which left no injuries or fatalities, resulted in the evacuation of 6,100 people, including 400 tourists.
