A Mysterious Chemical Cloud Descended on the British Coast

150 people were treated for stinging eyes, irritated throats and vomiting

The cloud was first reported at Birling Gap, located about 70 miles from central London. Poliphilo/Wikimedia Commons

Beachgoers were enjoying a leisurely, sunny Sunday on the UK’s East Sussex coast when a mysterious, chemical mist settled over the area. As Elle Hunt reports for the Guardian, beaches across the coast were evacuated, and some 150 people were treated for stinging eyes, irritated throats and vomiting. The haze has largely dissipated, but authorities still aren’t sure what it was or where it came from.

The noxious cloud was first reported on late Sunday afternoon at Birling Gap, located about 70 miles south of central London. According to the BBC, rescue teams rushed in to clear the coast, and residents were advised to keep their windows and doors shut. The local Eastbourne General District Hospital was inundated by people who had been affected by the haze.

The first patients to arrive were subjected to a “full decontamination treatment,” according to a police statement, but it soon became clear that such precautions were not necessary. Approximately 150 people were treated, but the complaints were by and large minor, and nobody was admitted to the hospital.

Details about the mist are still murky, but authorities have a pretty good idea of what it is not. As Ben Westcott of CNN reports, police say that weather conditions on Sunday make it “very unlikely” that the gas had wafted over from France—despite a 2013 incident that saw a foul-smelling gas leak out of a French factory and cover Southern England. And although social media users reported that the cloud smelled like chlorine, police insist it is “extremely unlikely” that the haze was comprised of the chemical, which can be used as a deadly weapon.

Scientists are now working with police to determine the source of the mist, according to Ben Farmer of the The Telegraph. A spokesperson for the Met Office, the U.K.’s national weather service, tells Farmer that there is “a possibility that it's something from a ship in the Channel and also the possibility that it came from the English Coast.”

The spokesperson also said that the chemical cloud may have been caused by “temperature inversion,” which occurs when a pocket of cold air is covered by a layer of warmer air. This phenomenon can trap pollutants that would disperse under other circumstances.

Fortunately, the mystery mist had cleared by Monday morning. Police advise anyone still experiencing symptoms to wash the affected areas with soap and water, and—if that doesn’t work—to contact emergency services.