Usually the area to be fumigated is sealed off and filled with a poisonous substance called a fumigant. The most widely used fumigants are gases, but liquids or solids that readily give off poisonous vapors are also used. Soil may be fumigated with applicators that inject a liquid under the surface. Common fumigants are formaldehyde and cyanide or chlorine compounds.
Many fumigants are explosive, some are harmful to plants, and most are dangerous to inhale or swallow. Fumigants often are most safely handled by trained exterminators.
