Novichok attack: What are the symptoms of nerve agent poisoning? How does it work?

ONE Briton has died and another is critically ill in hospital after exposure to the same nerve agent which sent Russian spy Sergei Skripal and his daughter into a coma earlier this year. So what are the symptoms of Novichok and how does it work?

The pair, named locally as Dawn Sturgess and Charlie Rowley, both in their mid-40s, were initially thought to be under the influence of a bad batch of heroin or crack cocaine. 

But it has now been confirmed the pair were suffering the effects of potentially deadly nerve agent Novichok.

A ‘major incident’ has been declared just eight miles from where Sergei Skripal and his daughter Yulia were struck by the poison. 

Neil Basu, Britain's most senior counter-terrorism officer, told reporters there was "nothing in their background to suggest" there was any reason for a targeted attack.

The confirmation the pair were suffering the effects of Novichok has sparked fears in the area that traces of the deadly substance remain.

Mr Rowley is being cared for in Salisbury hospital, the same location the Skripals spent weeks in a critical condition before making a slow recovery. 

Ms Sturgess died in hospital on Sunday at 8.26pm. 

What are the symptoms of nerve agent poisoning?

Professor Gary Stephens, a pharmacology expert at the University of Reading, said the chemical “causes a slowing of the heart and restriction of the airways, leading to death by asphyxiation.” 

Novichok attack: Officers in hazmatsGetty

Novichok attack: Officers in hazmat suits at the bench where the Skripals were found

Like all nerve agents, Novichok is designed to block messages from the nerves to the muscles, resulting in a collapse of bodily functions. 

Nerve agents can cause convulsions, loss of consciousness, wheezing, excessive fluid secretion, nausea, vomiting, diarrhoea, and profuse sweating.

A Russian doctor said the first sign to look out for is miosis - excessive constriction of the pupils. 

Death can occur by asphyxiation or cardiac arrest. 

There are antidotes that help stop the spread of the poison, however they are not a cure and they need to be administered as soon as possible, which can be tricky as nerve agent poisoning usually takes a while to diagnose. 

What is Novichok?

Novichok is a type nerve agent developed by the Soviet military dating the Cold War. 

The world novichok is Russian for ‘newcomer’.

Novichok attack: Police outside the house PA

Novichok attack: Police guard the house in Muggleton Rd where the couple where found

Novichok is highly illegal but was created in separate parts to avoid detection, making it easy to smuggle into the country. 

Professor Stephens said: “One of the main reasons these agents are developed is because their component parts are not on the banned list.”

There are more than 100 versions of Novichok, some of which are among the deadliest nerve agent ever created. 

Some versions can take effect within 30 seconds and the most likely route of exposure is through inhalation or absorption through the skin. 

If the agent is in a powder form, it can take longer to cause a reaction. 

Novichok attack: Officers in hazmat suitsGetty

Novichok attack: The public have been warned that they could see officers in hazmat suits

Is there a risk to the public?

Public Health England has released a statement saying the public in Salisbury “should avoid picking up unknown objects” as a “high precautionary” measure.

Health officials said on Wednesday the risk to the public was low.

England's Chief Medical Officer Sally Davies told reporters: “I want to reassure the public that the risk to the general public remains low.”