Anyone watching the TV adaptation of Stephen King’s “The Mist” would have felt extremely nervous if they were in Eastbourne, Sussex on Sunday, after a chemical mist – or gas cloud – came ashore on Birling Gap beach. Around 150 people required hospital treatment, while hundreds more were affected with vomiting, breathing difficulties and stinging eyes.

Origins of chemical gas are still a mystery

According to Sussex Police, the gas cloud appeared to have cleared by Monday morning, but authorities are still investigating the cause of the noxious mist, which could have originated either on-shore or from an off-shore location.

Police said in a statement that chemicals from European industrial units have previously affected the coastline, but in this case, due to the weather conditions, this is unlikely. However, the coastguard is reportedly working with its counterparts in France and investigating any vessels that were off-shore at the time of the incident.

Many media reports had quoted the mist as being "chlorine gas." However, according to the East Sussex Fire and Rescue Service, this is “extremely unlikely.” As the gas cloud spread along the crowded beaches, Coastguard rescue teams, fearing a chlorine leak, rushed to help clear visitors from the area.

Bob Jefferey, who works with the Royal National Lifeboat Institution, told the BBC that the gas smelled like “burned plastic” and that it hung around for so long because there was no wind at the time.

Residents and visitors speak of the noxious gas

Roy Page is on vacation in the area and was on the beach when what looked like a sea mist rolled in.

Page described the mist as being colorless and odorless, but said it was "seriously painful on the eyes".

The BBC quotes 28-year-old Jonathan Hill, who lives close to the beach, as saying he had returned home with his girlfriend from vacation on Sunday afternoon and immediately felt the effects of the chemical mist.

Hill said on arriving home, they opened the windows and soon afterward their eyes began to sting, adding that at one stage he could not see for around five minutes. As reported by Deutsche Welle, Hill headed to Twitter to say he thought it was hay fever at first, until authorities told them to close all windows and doors.

The Eastbourne General District Hospital saw long queues of patients waiting for treatment for the effects of the mist with around 150 receiving care. A spokesman for the hospital said they initially gave patients a full decontamination treatment but later found this was not necessary.

The video below shows the moment the chemical haze moved onto the beach.

Incident was ‘isolated’ but still under investigation

While police are still investigating the cause of the incident, they believe it was “isolated” and unlikely to recur. However, Kathy Ballard, a councilor for Eastbourne, said they need to find out what caused the chemical mist and where it came from, in order to take steps to prevent it from happening again. Ballard added that she had never heard of anything like this happening before in the area.

Meanwhile, on Monday, beaches in the area were open again with thousands of visitors enjoying the warm 25C (75F) weather.