Haze that led to 150 people seeking treatment caused a pollution spike and ‘might have been caused by a ship venting’

Authorities investigating the cause of Sunday’s chemical cloud are working on the assumption that it came from a ship in the Channel after environmental monitoring sites picked up a localised spike in pollution levels.

The Maritime and Coastguard Agency is working with the Environment Agency to establish the source of the cloud, which left 150 people seeking medical treatment and caused the evacuation of Birling Gap beach in East Sussex.

So far there is no evidence that the cloud came from an inland source, and authorities have also played down speculation that it could have drifted from as far as France.

A source close to the investigation said: “It might be a ship venting, but let’s wait and see.”



A satellite imaging agency may have located a possible source of the chemical plume to a boat close to the East Sussex shore. Neodaas, a facility of the UK Natural Environment Research Council that works with the Plymouth Marine Laboratory and the University of Dundee, tweeted images appearing to show a plume coming off a boat on Sunday morning.

One image showed a plume of around 3.5km long. Neodaas is urging the Met Office to help determine whether wind speeds at the time could have drawn the plume onshore.

Two pollution monitoring sites on the south coast picked up a quadrupling in ozone levels in a 30-minute period on Sunday afternoon, suggesting the toxic cloud came from a nearby ship.

One site at Devonshire Park in Eastbourne, and the national monitoring site at Lullington Heath, East Sussex, are both within five miles of Birling Gap.

Timothy Baker, from King’s College London’s environmental research group, which manages the pollution monitoring network for Sussex local authorities, said these readings suggested the source was nearby and offshore because of the wind direction at the time.

“We are not sure what it was, but there was a very distinct peak: the levels quadrupled at the time that incident was reported. Within the space of about half an hour the readings we were getting from those sites went from 30 up to about 120 parts per billion of ozone,” said Baker.

No other sites recorded a rise, he said. Similar levels of ozone pollution were reported during the 2003 heatwave, but at the time the levels did not rise so quickly, and no one reported stinging eyes, sore throats and vomiting as they did on Sunday.

Baker said: “The most likely scenario is that it was either ozone combined with something else, or it is something that has reacted in a similar way to ozone and hence triggered the analysers.”



He added: “It was probably something relatively close. I’ve heard speculation that it may have drifted over from France. The speed of the rise and very isolated points at which it was detected would seem to indicate that was less likely, because the further away the source the more it spreads.

“All the indications were that the wind was coming in off the sea at the time.”

Asked if the pollution came from a ship, he said: “All I can say is that it was something that came in off the sea.”

An Environment Agency spokesman said: “We are currently investigating any potential onshore sources of the pollution and to date we have not identified anything that could be attributed to the mist and we are liaising with the Maritime and Coastguard Agency, who are doing similar investigations offshore.”



Baker said the source of the cloud was still a mystery. “We have spent most of the day looking at it and we haven’t got a definitive answer yet. We don’t think it is just ozone that caused it. The monitoring sites don’t record all possible pollutants. If it was an unusual chemical it is possible that it may have triggered a similar reaction within the analyser to ozone.”

Nothing was seen on other polluting detectors including those for nitrogen dioxide, Baker said.

“Ozone is not an emitted pollutant. It is caused by reactions within the atmosphere. The levels of pollution didn’t indicate that this was a normal reaction, because ozone usually rises slowly and builds to a peak during the middle of the afternoon. This went up to four times what it was in half an hour,” he said.

East Sussex fire and rescue service said the investigation was likely to take some time.

Gas-monitoring equipment used in the aftermath of the incident failed to conclusively identify the gas, it said. It said the expert team investigating the incident concluded that the gas was unlikely to be chlorine “due to the symptoms and situation described”.

It added: “All agencies involved ask that investigators are given time to carry out their work rather than speculate on possible causes.”