Chemical agents

UK Prime Minister Theresa May has told parliament that a military-grade nerve agent was used in an attack on former Russian double agent Sergei Skripal. May says the substance used belongs to the Novichok group of nerve agents, but what are Nivochok agents and what do they do?

Scientists have developed a fabric that not only blocks chemical warfare agents, but actively breaks them down, something they say is a step up on currently available technologies.