March 11, 2018

expert reaction to PHE health advice for those in Salisbury near the area where the poisoned Skripals were found

PHE have offered health advice for those in the pub and restaurant in the surrounding area where the Skripals, who were poisoned with a nerve agent, were found.

Prof Alastair Hay, Professor Emeritus of Environmental Toxicology, University of Leeds, said:

“At the moment the forensic teams will be testing all possible locations for evidence of the nerve agent. The sites may reveal where the agent was administered but, less likely given small amounts, where secondary contamination may have occurred as a result of contamination on the clothing of father and daughter.

“It is important to note that nerve agents do degrade in the environment so you want to collect any evidence as soon as possible. Contact with moisture will lead to breakdown of the nerve agent – this is why people having visited the restaurant or pub in question last Sunday afternoon or Monday are being advised to wash their possessions. The advice to wash belongings is a precautionary measure. If no one has had physical symptoms suggestive of nerve agent contact by now it is unlikely that they are a risk. But washing will provide the extra guarantee of safety.

“Nerve agents vary in their rate of environmental breakdown. Sarin is one of those that degrades more rapidly whereas VX is more persistent. Other nerve agents are sort of in between in terms of degradation. Nerve agents will form vapours and evaporate, i.e. they will disappear. This varies between agents and vapours form more readily the higher the ambient temperature.

“In the recent poisonings the agent is much more likely to be on surfaces and so vapourisation and hydrolysis (breakdown through contact with water) will be the major factors which determine how long the nerve agent will be present and how easy it is for investigative teams to work out where the pair came into contact with it.”

Declared interests

None received.