During a visit to a beach in Saint-Michel-en-Greve, Brittany, French Prime Minister Francois Fillon announced that the French government will pay to have the beaches of France cleaned from toxic seaweed.

The state will assume all of its responsibilities and will take charge of the clean-up of the worst affected beaches, where there could be a public health risk,” he said.

Local communities in Brittany have long been urging the government to do something about the toxic green algae that has been flourishing on Brittany beaches for years.

Last month, a rider was rendered unconscious on the Saint-Michel-en-Greve beach and his horse died after slipping on the algae, apparently after inhaling the toxic gas hydrogen sulphide released by the rotting weed. Investigations carried out by France’s National Institute for Environmental Technology and Hazards (Ineris) showed a potentially lethal concentration of the gas on parts of the beach. Some stretches had a concentration of 1,000 hydrogen sulphide parts per million; a concentration which can be deadly in just a few minutes. Ineris recommends providing all cleaning workers with gas detectors and ban the public from the beach until its deemed safe.

The green seaweed thrives when the levels of nitrate is high, which means that excess field fertilizers and manure from local livestock flushed into the ocean by French farmers creates an ideal environment for the algae.

The algae problem is not peculiar to France; the same type of green algae is also turning up along the UK coast line, especially in Dorset, Hampshire, West Sussex, and on the Isle of Wight. According to the UK Environment Agency, the algae are a threat to wildlife along the coast and tighter controls on farming fertiliser and sewage plants will be required to starve the algae of nutrients.