Fumigation

Fumigation is pest control with a gas. A fumigation crew seals a building, a chamber, a container or a commodity, introduces a fumigant that reaches every void and crevice, holds it for the required time, then airs out the space and proves with instruments that it is safe to re-enter. BLS describes fumigators as applicators who seal buildings and use gases to treat large-scale infestations. Structural fumigation with sulfuryl fluoride treats drywood termites, wood-boring beetles, bed bugs and other pests in whole buildings. Commodity fumigation with phosphine-releasing products protects stored grain and other products. The fumigants are highly hazardous. The Vikane label calls sulfuryl fluoride a highly hazardous material that must be used only by people trained in respiratory equipment, gas detection and emergency procedures, and NIOSH lists 200 ppm as immediately dangerous to life or health. Every state this site covers treats fumigation as its own category, often with extra prerequisites. The field suits experienced, disciplined applicators who follow procedure exactly, every time. It is not an entry-level job.

A structural fumigation starts well before the gas. The crew confirms the job details and the state notice. Florida, for example, requires the company to notify the state agency at least 24 hours before a general fumigation, naming the fumigant, the certified operator or fumigation ID cardholder in charge, the structure, the date, the target pest and the duration. The occupants must have left, with people, pets and desirable plants removed, and food, feed, drugs and medicines removed unless they are sealed as the label allows. The Vikane label also requires an adult occupant to receive the product's fact sheet. In apartments and townhouses, if one unit is fumigated, the label requires every unit in the structure to be vacated.

Then the building is sealed. For a tarpaulin fumigation, the Vikane label calls for a highly resistant material such as vinyl-coated nylon or polyethylene sheeting at least 4 mil thick, sealed at the ground. O*NET lists positioning and fastening tarpaulin edges over the building and taping vents to make it airtight and check for leaks among the tasks of pest control workers. That means ladders, roof work and heavy tarps. Every exterior door gets a secondary lock or barricade so only the state licensed applicator in charge can get in, and warning placards go up showing the date, the fumigant and the applicator's name, address and phone number.

Before releasing the fumigant, the crew calculates the dose for the volume and conditions, and introduces chloropicrin as a warning agent. The label says chloropicrin causes smarting of the eyes and tears and must be released inside at least 5 to 10 minutes before the fumigant. The fumigant itself is released from outside the structure. The label requires two trained people, at least one a state-licensed or certified applicator, to be present during introduction, during any re-entry before aeration, and at the start of the initial aeration whenever exposure exceeds 1 ppm. Anyone entering above 1 ppm wears a positive-pressure self-contained breathing apparatus.

Aeration and clearance are where discipline matters most. Under one of the Vikane label's aeration procedures, the crew opens the structure and runs fans capable of moving a total of 5,000 cubic feet per minute for at least an hour, wearing respiratory protection, then secures the building for at least 6 hours from the first opening of the seal. Afterward the crew measures the concentration in the breathing zone of every room, where people stand, sit or lie down, with an approved clearance device. Only when every reading is 1 ppm or less may a certified applicator authorize removing the placards and re-occupying the building.

Commodity fumigation follows the same logic in a different setting. USDA's grain fumigation handbook, which covers ships' holds, land carriers and river barges, describes the certified applicator inspecting holds for their ability to keep gas in, writing a signed statement on which holds are suitable, choosing the application method and dose, holding a pre-fumigation conference with the vessel's officer, placarding every entrance, and confirming carriers are gas free, which for metal phosphide is 0.3 ppm or less. Throughout, the paperwork is as important as the gas.