The CN compounds hydrolyse slowly in water with subsequent gradual loss of toxicity. They are neadily oxidised by strong oxidants, e.g., potassium permanganate. Use is made of this property in some forms of therapy. Hydrogen cyanide, because of its volatility and low molecular weight, is poorly absorbed by the charcoal in the canister of the respirator. This charcoal is therefore impregnated with metal salts in order to improve the performance of the canister, but the protection provided against HCN is not unlimited.
Automatic detectors are available which detect attack concentrations of cyanide vapour.
Draeger tm tubes are also available, as are water testing kits. Specialist equipment including a respirator, NBC suit, gloves and overboots give good protection. Modern NBC filters are effective against attack with hydrogen cyanide, but should be changed immediately afterwards. Because of its physical properties the agent will not remain for long in its liquid state. Decontamination should not, therefore, be necessary.