Fumigants

Fumigants are pesticides that are applied as gases or vapors to eliminate pests in enclosed spaces, commodities, or soils. They differ from liquid or solid pesticides because their vapors diffuse through air spaces, cracks, and porous materials to reach hidden life stages. Fumigation is widely used for stored products, quarantine and in-transit pest control, soil disinfestation, and structural treatments of buildings, ships, and greenhouses.

Common fumigants include phosphine, which is often generated from metal phosphides for grain and other stored products; sulfuryl fluoride; and chloropicrin, which is frequently used in combination with other gases to enhance effectiveness and provide a warning effect. Methyl bromide was historically a staple for many applications but has been largely phased out under the Montreal Protocol due to ozone depletion, with only limited critical-use exemptions in some regions. Other soil fumigants and gas-generating formulations (such as mixtures used in greenhouse and field contexts) target nematodes, fungi, weed seeds, and other soil-borne pests.

Safety and regulatory considerations are central to fumigation. Fumigants are highly toxic to humans and non-target organisms; treatments require sealed environments, proper gas monitoring, ventilation after treatment, and adherence to strict re-entry intervals and dose limits. Certification, training, and specific handling procedures are mandated in many jurisdictions.

Environmental and agricultural implications include potential residues in food, effects on non-target organisms, and, for ozone-depleting agents, broader atmospheric impacts. Resistance can occur, and fumigation is often integrated with other pest management strategies to balance efficacy, safety, and sustainability.