What Caused the Toxic Cloud in Sussex?

The end of August saw a mysterious chemical mist engulf Birling Gap beach in East Sussex, resulting in the evacuation of the area and the admittance of approximately 150 people to hospital. Reporting symptoms of stinging eyes, vomiting and respiratory complications, the victims were thankfully all cleared within hours of the incident taking place, as was the beach itself.

Two weeks on, do we have any more information about what caused the toxic cloud to form over southern England?

What happened?

Birling Gap beach was awarded the Blue Flag in 2005, signifying excellent water quality levels and superb facilities. Unfortunately, water quality levels have dropped on many UK beaches in recent years (including at Beachy Head), meaning the strand no longer enjoys Blue Flag status, but it’s still a very popular holiday destination.

On the day in question (Sunday 27^th August), southern England was experiencing particularly hot weather, meaning Birling Gap was positively jam-packed with families and beach-goers. However, just before 5pm, an ominous mist descended on the beach, causing those on it to experience adverse symptoms.

With more and more people complaining of difficulty breathing, stinging eyes and involuntary vomiting, and with an easterly wind blowing the mist across the Beachy Head coastline, authorities took the decision to evacuate the region and advise against visiting any part of the shoreline.

As lengthy lines built up at nearby Eastbourne hospital, the NHS initially treated it as a chemical incident. This involved comprehensive decontamination procedures, though after screening the first sufferers, it soon became clear this was unnecessary. Then, almost as quickly as it had descended, the toxic cloud dissipated.

Possible causes

An investigation is ongoing into the cause of the mysterious mist, and although experts have yet to come to a definitive conclusion, there are a few theories floating around about what could have caused the cloud. These include:

• A chlorine leak. One bystander described the gas as "a colourless, odourless mist that was seriously painful on the eyes" – such a description is in keeping with chlorine, though East Sussex Fire and Rescue Service have since dismissed such a hypothesis as “extremely unlikely”.
• Emissions from industrial plants on the continent. Due to chemical emissions from French industrial units arriving at British shores in the past, it was mooted that perhaps the same thing had happened again. However, Sussex Police have said that “weather models suggest that an onshore source in northern France is very unlikely”.
• Passing ships in the Channel. Offshore sources, including passing vessels, are still being investigated. Around 180 different ships have been identified as passing through the Channel on the day in question, leading experts to surmise that one of these is the most likely source of the mist.
• A wartime shipwreck. The Maritime and Coastguard Agency (MCA) have since announced the possibility that chemicals from a sunken shipwreck may have been to blame. In particular, a WWI oil tanker SS Mira has been suggested as releasing a latent toxic plume into the area, which was subsequently blown towards Beachy Head. However, with 100 years having passed since the ship was initially downed, a release of chemicals at this stage remains unlikely.

As yet, the cause remains unknown and investigations are ongoing. But with public concerns about pollution at an all-time high (as attested to by the impressive growth at this year's Air Quality and Emissions event), there will be pressure on the authorities to pinpoint the culprit and prevent a repeat performance from happening again in the future.