What is a requirement for phosphorus-based burrowing pest fumigation?

The requirement that phosphorus-based burrowing pest fumigation must be conducted at least 100 feet from any building where humans may reside is grounded in safety regulations aimed at minimizing exposure to potentially hazardous gases and vapors produced during the fumigation process. Phosphine gas, generated when phosphorus compounds are applied, can disperse widely and poses health risks. Establishing a buffer zone helps protect human occupancy and ensures that the application can be carried out effectively without endangering nearby residents.

The other options suggest conditions that are either too restrictive or not applicable. For instance, fumigation can occur in various settings beyond just indoors or agricultural areas, and while ventilation is important for safety, it is not specified as a strict requirement for this type of fumigation. Thus, maintaining a safe distance from residences is a critical and specific guideline that supports the safe use of phosphorus-based fumigation.