Question

which is the gaseous fumigant

Answer 1

A residential property in Los Angeles, subject to tent fumigation or "tenting".

Fumigation of a hotel (Vila Shanti) in Bali where the smoke even reaches the hotel lobby (Feb 2010).

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.