Fumigation is a method of pest control or the removal of harmful micro-organisms by completely filling 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. Fumigation is also used during the processing of goods for import or export to prevent the transfer of exotic organisms. Structural fumigation targets pests inside buildings (usually residences), including pests that inhabit the physical structure itself, such as woodborers and drywood termites. Commodity fumigation, on the other hand, is also to be conducted inside a physical structure, such as a storage unit, but it aims to eliminate pests from infesting physical goods, usually food products, by killing pests within the container which will house them. Each fumigation lasts for a certain duration. This is because after spraying the pesticides, or fumigants, only the pests around are eradicated. Process Fumigation generally involves the following phases: first, humans are evacuated from the area intended for fumigation and the area covered to create a sealed environment. Next, the fumigant is released into the space to be fumigated. The space is held for a set period while the fumigant gas percolates through the space and acts on/kills any infestation in the area. Finally, the space is ventilated so that the poisonous gases are allowed to escape from the space, rendering it safe for humans to enter. If successful, the fumigated area is now safe and pest free. Tent fumigation Structural fumigation techniques differ from building to building. In a residential setting, a "rubber" tent or tents, typically made of plastic/pvc coated canvas material, may be 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. Operating theatres 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. 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 it is a cost-effective procedure. However, alternative methods are