Which is NOT a disadvantage of fumigants?

Fumigants are gases that can penetrate materials and are effective for controlling a wide range of pests in various environments. However, one aspect that distinguishes the correct answer from the others is that the cost of fumigants can vary significantly depending on the type and dosage required. While fumigants can indeed be expensive to use when considering the full scope of application, safety measures, and the need for specialized equipment, the option that states they are inexpensive is not a valid disadvantage.

The other choices highlight genuine limitations of fumigants: they can only be applied in enclosed areas to ensure proper containment and effectiveness, their application often requires specialized knowledge and techniques which can make them difficult to apply, and due to their potential toxicity, applicators must frequently use full protective gear to ensure safety, which adds to the complexity and cost of their use. These factors together create a more comprehensive understanding of the challenges presented when using fumigants in pest control.