What is a common feature of control areas in a building?

Control areas within a building are specifically designed to manage and contain hazardous materials effectively. A key feature of these areas is that they are bounded by fire barriers and exterior walls. This design serves several important functions: it helps to contain any potential fire or explosion that may occur, limits the spread of hazardous fumes, and ensures a clear separation from non-hazardous areas.

By having fire barriers, the integrity and safety of adjacent areas are protected. These physical barriers also contribute to compliance with safety regulations, ensuring that the risks associated with hazardous materials are minimized.

The other choices, while they may provide some benefits or serve specific purposes, do not encapsulate the primary defining feature of control areas as distinctly as the use of fire barriers and exterior walls. High ceilings for ventilation and external access points can be useful, but they don't necessarily define a control area's primary function. Designated areas for non-hazardous materials might coexist with a control area, but they are not a defining feature either.