As of right now, many British holidaymakers are being told to stay away from beaches located in northern France. These warnings have been issued due to toxic fumes that are being given off by rotting seaweed. This problem has now led to one area of the beach at Saint Michel en Greve in Brittany to be shut down. The beach was shut after a horse rider lost consciousness and his horse died after being exposed to the fumes.

A member of the French Institute of Sea Research and Exploitation, Gilles Youenou, said that they advise people to avoid these beaches. The seaweed is giving off hydrogen sulphide fumes. This can be the result of a problem with agriculture. He noted that Nitrates have gotten into the water and polluted it.

Gilles Youenou went on to say that normally a crust forms over stacks of rotting seaweed. When the crust is broken, fumes are released. These fumes can be particularly lethal to dogs, as well as other animals. This helps to explain why the horse was killed.

A spokesman for the French environmental group Eau et Rivieres said that toxic seaweed has been found on the beaches of Brittany for quite some time. Now the problem seems to be spreading. He noted that there are already almost five beaches that are unusable, and the problem is just getting worse.

Eau et Rivieres says that almost 70,000 cubic meters of seaweed has to be cleared off from 70 beaches every summer in Brittany. The Lannion hospital in Brittany has said that the hydrogen sulphide is as dangerous as cyanide. The hospital has already treated many cases of poisoning caused by the seaweed among local residents. This included one council worker who was paid to clear beaches of algae. The woman was found in a coma.