CHAPTER 2
Exposure Control Strategies and the Hierarchy of Controls
Controlling exposures to occupational hazards is the fundamental method of protecting workers. Traditionally, a hierarchy of controls has been used as a means of determining how to implement feasible and effective controls. Figure 4 shows one representation of this hierarchy. The idea behind the hierarchy of controls is that the control methods at the top of the triangle are generally more effective in reducing the risk associated with a hazard than those at the bottom. Following the hierarchy normally leads to the implementation of inherently safer systems, ones where the risk of illness or injury has been substantially reduced. Designing out hazards early in the design process is a basic tenet of PtD. When PtD is implemented, the control hierarchy is applied by designers and owners/managers to include safety into the process. The following sections discuss each element of the hierarchy of controls—elimination, substitution, engineering controls, administrative controls, and PPE—and how it may relate to nanotechnology.
2.1 Elimination
Elimination and substitution are generally most cost effective if implemented when a process is in the design or development stage. If done early enough, implementation is simple and, in the long run, can result in substantial savings (e.g., cost of protective equipment, first cost and operational cost for ventilation system). For an existing process, elimination or substitution may require major changes in equipment and/or procedures in order to reduce a hazard.
Figure 4. Graphical representation of the hierarchy of controls
Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes
