Fumigation is a metho of pest control that completely fills an area with gaseous pesticides 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. 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 residence. This concentrates the gases and prevents them from escaping and doing harm to people in the neighborhood. During this time the residents of the house must find an alternate residence for up to a week depending on the fumigant used, which in turn depend on the severity of infestation and size of the house.