What are hand plunger dusters primarily used for?

Hand plunger dusters are specifically designed for dusting applications, particularly in areas where precision is required. They allow for the application of pesticide dust into structural openings such as cracks, crevices, or voids where pests tend to hide or enter. This precise method ensures that the dust reaches the intended target effectively without excessive dispersal, which is critical for both efficacy and safety.

The other options relate to different types of application methods that are not suited to the precise, localized application of dust that hand plunger dusters provide. Spraying liquids at high pressure is characteristic of sprayers rather than dusters, while applying pesticides via compressed air is a unique method typically involving specialized equipment. Distributing granular materials evenly does not align with the function of hand plunger dusters, which are meant for dust rather than granular substances. Thus, the primary application of hand plunger dusters is indeed for dusting into structural openings.