Hierarchy of controls

The core idea is that controls that act on the hazard itself are more dependable than controls that depend on people. Elimination removes the hazard, for instance by dropping a solvent step from a process. Substitution replaces a dangerous chemical with a less hazardous one, such as a water-based cleaner instead of a flammable solvent.

Next come Engineering controls, which isolate people from the hazard through enclosure, ventilation or process changes. Local exhaust ventilation (LEV) and a Chemical fume hood are common examples. Administrative controls follow: written procedures, training, job rotation, signs, scheduling and limiting the time or number of workers exposed. These rely on people following the rules.

Personal protective equipment (PPE) sits at the bottom of the hierarchy. It is still necessary in many situations, but it only works if selected, fitted, worn and maintained correctly, and a single failure leaves the worker unprotected. The hierarchy does not mean PPE is unimportant; it means it should not be the first answer.

In practice, controls are combined. A process might use a less hazardous chemical, a ventilated enclosure, a written procedure and gloves. SDS information helps at each level: Section 2 shows the hazard, Section 7 describes safe handling, and Section 8 lists exposure controls. When reviewing a task, ask first whether the chemical or step can be removed or replaced before adding equipment.