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Fumigation

Fumigation

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Encyclopedia
Fumigation is a method of pest control
Pest control
Pest control refers to the regulation or management of a species defined as a pest, usually because it is perceived to be detrimental to a person's health, the ecology or the economy.-History:...

 that completely fills an area with gaseous pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...

s—or fumigants—to suffocate or poison the pests within. It is utilized for control of 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
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

. This method also affects the structure itself, affecting pests that inhabit the physical structure, such as woodborers and drywood termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...

s.

Process


Fumigation usually involves the following phases: First the area 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
Infestation
Infestation refers to the state of being invaded or overrun by pests or parasites. It can also refer to the actual organisms living on or within a host.-Terminology:...

 in the product, next the space is ventilated so that the poisonous gases
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....

 are allowed to escape from the space, and render it safe for humans to enter.

Tent fumigation (Tenting)


Structural fumigating techniques differ from building to building, but in houses a rubber tent is 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 in turn depend on the severity of infestation and size of the building.

Chemicals


Methyl bromide was among the most widely used fumigants until its production and use was restricted by the Montreal Protocol
Montreal Protocol
The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances believed to be responsible for ozone depletion...

 due to its role in ozone depletion
Ozone depletion
Ozone depletion describes two distinct but related phenomena observed since the late 1970s: a steady decline of about 4% per decade in the total volume of ozone in Earth's stratosphere , and a much larger springtime decrease in stratospheric ozone over Earth's polar regions. The latter phenomenon...

.

Widely used fumigants include:
  • phosphine
    Phosphine
    Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...

  • 1,3-dichloropropene
    1,3-Dichloropropene
    1,3-Dichloropropene, also known as Telone or simply 1,3-D, is a colorless liquid with a sweet smell. It exists as a mixture of the geometric isomers cis-1,3-dichloropropene and trans-1,3-dichloropropene. It dissolves in water and evaporates easily. It is used mainly in farming as a pesticide,...

  • chloropicrin
    Chloropicrin
    Chloropicrin, also known as PS, is a chemical compound with the structural formula Cl3CNO2. This colourless highly toxic liquid was once used in chemical warfare and is currently used as a fumigant and nematocide.-History:...

  • methyl isocyanate
    Methyl isocyanate
    Methyl isocyanate is an organic compound with the molecular formula CH3NCO. Synonyms are isocyanatomethane, methyl carbylamine, and MIC. Methyl isocyanate is an intermediate chemical in the production of carbamate pesticides . It has also been used in the production of rubbers and adhesives...

  • hydrogen cyanide
  • sulfuryl fluoride
    Sulfuryl fluoride
    Sulfuryl fluoride is the inorganic compound with the formula SO2F2. This easily condensed gas has properties more similar to sulfur hexafluoride than sulfuryl chloride, being resistant to hydrolysis even up to 150 °C...

  • formaldehyde
    Formaldehyde
    Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...

  • Iodoform
    Iodoform
    Iodoform is the organoiodine compound with the formula CHI3. A pale yellow, crystalline, volatile substance, it has a penetrating odor and, analogous to chloroform, sweetish taste. It is occasionally used as a disinfectant...


Safety


Fumigation is a hazardous operation. Generally it is a legal requirement that the operator, carrying out the fumigation operation, holds official certification
Certification
Certification refers to the confirmation of certain characteristics of an object, person, or organization. This confirmation is often, but not always, provided by some form of external review, education, assessment, or audit...

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.

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