Ventilation, glove boxes, and hot cells are examples of:

Ventilation, glove boxes, and hot cells are primarily categorized as engineering controls because they are designed to minimize or eliminate exposure to hazardous conditions in a workplace, particularly in environments where radiation is present.

Engineering controls involve physical modifications to the work environment that effectively reduce or manage the risk of exposure to harmful agents. For example, proper ventilation systems help to dilute or remove airborne contaminants, thus reducing inhalation exposure. Glove boxes are ventilated enclosures allowing workers to handle radioactive materials while maintaining a barrier between the worker and the hazardous substance, thereby protecting the worker from direct contact. Hot cells are specialized areas designed to safely contain radioactive materials, providing a controlled environment for the handling and processing of such materials.

In contrast, administrative controls involve policies and procedures to manage exposure risks, personal protective equipment (PPE) includes items like gloves, masks, and protective suits, and the conduct of work refers to the practices and behaviors that ensure safety during operational tasks. Each of these categories plays an important role in an overall safety program, but for the question at hand, the focus is appropriately placed on the direct modifications and safeguards provided by engineering controls.