Novichok nerve agent Two British citizens are critically ill after being exposed to Novichok – the same nerve agent used in the poisoning of a former Russian spy and his daughter in the city of Salisbury in March Origin: Created in Soviet Union in 1970s and 1980s. Made with agrochemicals so that nerve agent could be hidden from Organisation for the Prohibition of Chemical Weapons Toxicity: Believed to be five to 10 times more lethal than VX and sarin nerve agents, and harder to identify Variants: Exists in liquid or solid form, including ultra-fine powder. Can be stored or carried as two less toxic ingredients, which become lethal when mixed Effect: Occurs within as little as 30 seconds to two minutes if agent is inhaled or touches skin. Fine powder can take 18 hours to act Exposure: Victim’s clothing should be removed and their skin washed with soap and water. Antidotes such as oximes can be effective if administered quickly. Some Novichok variants specifically designed to resist standard antidotes SYMPTOMS: Messages between nerves and muscles are blocked – causing bodily functions to collapse Brain: Reduced oxygen in body can lead to coma and brain damage Eyes: Pupils constricted Skin: Profuse sweating Lungs: Breathing inhibited, extreme fluid secretion Heart: Abnormal blood pressure and heart rate Digestive system Nausea, vomiting and diarrhoea Typically, muscle spasms and seizures occur, leading to death by asphyxiation or cardiac arrest Sources: Associated Press, BBC, Live Science, Reuters Picture: Getty Images © GRAPHIC NEWS