Used by Iraq in the Iran war against the Kurds in the 1980's, and also by the Nazis in the gas chambers of concentration camps, cyanide agents are colourless liquid which is inhaled in its gaseous form while liquid cyanide and cyanide salts are absorbed by the skin. Symptoms are headache, palpitations, dizziness, and respiratory problems followed later by vomiting, convulsions, respiratory failure and unconsciousness and eventually by death.