Beachy Head
A general view of the cliffs at Beachy Head near Eastbourne, England.Dan Kitwood / Getty Images

A mystery haze along East Sussex coast that prompted the evacuation of a local beach may have been caused by a shipwreck, the coastguard agency has said.

First reports of the Birling Gap gas cloud came through last Sunday (27 August), after which residents were advised to close their windows and avoid contact with the "chemical haze". Around 150 people sought medical treatment for vomiting, streaming eyes, and respiratory problems.

The Maritime and Coastguard Agency has now said that while the cloud's origin is still unknown, it may have been caused by emissions from the English Channel's numerous shipwrecks.

The agency also noted that it is investigating discharges from ships that passed through the area, as well as any possible lost cargo.

"We have identified approximately 180 vessels that passed through the English Channel off the coast of Eastbourne on Sunday 27 August," it said in a statement. "We are working with all relevant Environmental and Public Health regulators to conclude these investigations."

It had been thought that the thick mist came from European industrial units that drifted over the English Channel, although this was later disputed by the Met Office, which noted that weather models effectively ruled out any suggestion that the cloud came from northern France.

The main area affected by the haze stretched several miles from Birling Gap beach to the famous cliffs at Beachy Head, and to the Sovereign Harbour on the eastern fringes of Eastbourne. Many businesses in Eastbourne were also forced to close.

Coastguard rescue teams from Birling Gap, Eastbourne, Bexhill and Newhaven all helped clear the beaches, with some residents claiming that they could smell chlorine. The fire service later allayed these fears, stating that it was "extremely unlikely" to be the chemical.