Poisonous gases and vapours

Poisonous gases include heavy metal vapours, coal gas, carbon monoxide, butane, propane, liquefied petroleum gas, acetylene, water gas, exhaust gases from combustion engines, ammonia, carbon dioxide, carbon tetrachloride, chlorine, chloroform gas, cyanide gas and cyanide compound vapours. Gases when used normally as prescribed anaesthetics are not viewed as being poisonous.