Reducing risk to a level that is considered as low as reasonably possible should be the primary goal of every Occupational Safety and Health professional. Using risk reduction strategy according to the hierarchy of controls is one of the concepts OSH professionals employ to achieve this goal. This concept ranks control measures in terms of their effectiveness in controlling or eliminating hazards, the basis being that the control measures at the top of the ranking are more effective than those at the bottom. Inherently, safer systems are usually implemented when this hierarchy is followed, which also leads to a substantial reduction in risks of injury and illness.

Different hierarchy of control models have been developed over years; however, the National Institute for Occupational Safety and Health through its Prevention through Design initiative represents the hierarchy of controls as follows:

• Elimination. This requires physically removing the hazard or risk from the system or workplace. It is considered the most effective but most difficult method to implement in an existing system. An example could be eliminating a hazardous chemical process from a jobsite.
• Substitution. This means replacing the hazard or risk with a less hazardous system. For a similar example, it could encompass replacing a highly hazardous chemical with a less hazardous one.
• Engineering Controls. This means isolating people from the hazard. An example could be installing guards on equipment to keep workers away from potential hazards, or rerouting trucks and footpaths away from overhead power lines.
• Administrative Controls. This basically means changing the way people work, limiting people’s exposure by adjusting work tasks or schedules. Examples include limiting the time the worker is exposed to a hazard and using warning signs.
• Personal Protective Equipment. This requires the use of PPE to protect the worker. In construction this might include hard hats, safety glasses, steel-toed shoes, ear protection, gloves, etc. Although a lot of attention is paid to PPE, it is considered the least effective of all the controls.

Reducing risk through the use of the hierarchy of controls is a fundamental way of protecting workers. One of the best ways to ensure workers are implementing the control methods is by conducting operational risk management (ORM) daily work briefings, in which the hierarchy of controls is a key topic. This is considered a “human performance tool” intended to generate awareness of hazards and lead workers to modify jobsites, workflow and procedures for the purpose of reducing error or potential for error. The ORM should be designed to ensure every task is analyzed and carried out safely. 

As part of ORM, ask workers to identify hazards associated with their tasks, and devise ways of controlling the hazards. Employees should be adequately trained to control all hazards by following the hierarchy of controls in order of effectiveness. For example, it’s wise to consider fabricating work on the ground to eliminate fall hazards, substitute the use of ladders with lifts where feasible, embed sleeves in slabs to prevent core drilling, rotate jobs among employees, use caution signs and always engage PPE as the final line of defense against hazards.

The use of the hierarchy of controls should be at the core of all risk-reduction strategies. Emphasis should always be placed at the top of the hierarchy, which requires eliminating or substituting the hazard when feasible. There is no doubt that when effectively implemented, this hierarchy helps create a safer and healthier workplace.