Fumigation is a method of pest control that completely fills an area with gaseous pesticides—or fumigants—to suffocate or poison the pests within. It is used to control pests in buildings (structural fumigation), soil, grain, and produce, and is also used during processing of goods to be imported or exported to prevent transfer of exotic organisms. This method also affects the structure itself, affecting pests that inhabit the physical structure, such as woodborers and drywood termites.
Fumigation generally involves the following phases: First the area intended to be fumigated is usually covered to create a sealed environment; next the fumigant is released into the space to be fumigated; then, the space is held for a set period while the fumigant gas percolates through the space and acts on and kills any infestation in the product, next the space is ventilated so that the poisonous gases are allowed to escape from the space, and render it safe for humans to enter. If successful, the fumigated area is now safe and pest free.
Structural fumigation techniques differ from building to building, but in houses a rubber (usually the tent is made of plastic\pvc coated canvas material) tent(s) are often placed over the entire house while the pesticides are being released into the vacant residence. This process is called tent fumigation or "tenting". The sealed tent concentrates the poisonous gases and prevents them from escaping into the neighborhood. The process can take up to a week depending on the fumigant used, which is in turn dependent on the temperature and the pest.
Fumigation of hospital rooms with high concentrations of toxic chemicals has been proposed to reduce microbial agents on hospital surfaces and to control surgical site infections. For this formaldehyde fumigation has long been an accepted method for areas where microbiological cleanliness is required. Fumigation with formaldehyde vapor is the recognized and most commonly used method because of its cost effective procedure.  However, due to safety and efficacy concerns there is a need for alternative methods. Vaporized Hydrogen Peroxide is a dry gaseous method that has been used as a reliable alternative for aseptic processing isolators and more recently for room/facility decontamination.
- Methyl bromide was among the most widely used fumigants until its production and use was restricted by the Montreal Protocol due to its role in ozone depletion.
- dazomet (methyl isothiocyanate precursor)
- hydrogen cyanide
- methyl isocyanate
- sulfuryl fluoride
Fumigation is a hazardous operation. Generally it is a legal requirement that the operator who carries out the fumigation operation holds official certification to perform the fumigation as the chemicals used are toxic to most forms of life, including humans.
Post operation ventilation of the area is a critical safety aspect of fumigation. It is important to distinguish between the pack or source of the fumigant gas and the environment which has been fumigated. While the fumigant pack may be safe and spent, the space will still hold the fumigant gas until it has been ventilated.
- W. G. Johnson, Fumigation Methods (New York, 1902)
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- "Operation Theatre Sterilization by Fumigation".
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- Messenger, Belinda; Braun, Adolf (2000). "Alternatives to Methyl Bromide for the Control of Soil-Borne Diseases and Pests in California" (PDF). Pest Management Analysis and Planning Program. California Department of Pesticide Regulation. Retrieved March 1, 2016.
- Decanio, Stephen J.; Norman, Catherine S. (2005). "Economics of the 'critical use' of methyl bromide under the Montreal Protocol". Contemporary Economic Policy. 23 (3): 376–393. doi:10.1093/cep/byi028. SSRN 904751.