A Russian chemical weapons scientist has told Sky News that people exposed to even tiny traces of the nerve agent used to attack a spy and his daughter in Salisbury could be in danger of developing symptoms in years to come.
Dr Vil Mirzayanov is a chemist who ran the technical counter-intelligence department in Russia's chemical weapons institute.
He helped make "novichok", the class of nerve agents the British government says was used to poison defected spy Sergei Skripal and his daughter Yulia.
news.sky.com/story/spy-poisoning-novicho...k-for-years-11287880