Hazard Hierarchy

In relation to health and safety, a hazard is generally defined as ‘a potential source of harm or adverse health effect on a person or persons.’

The hazard hierarchy is a system used in industry to minimise or eliminate exposure to hazards.

A number of control measures can be implemented to reduce the potential exposure to the hazard or to remove the hazard. The hierarchy lists these control measures, in order of decreasing effectiveness. The control measures are:

  1. Elimination

Totally removing the hazard eliminates the risk of exposure and is the most effective hazard control. For example, remove the risk from working at height by having workers perform tasks at ground level rather than at height.

  1. Substitution

This method of control involves substituting a process or material for a safer or less hazardous one.  For example, substituting benzene with toluene in laboratories. The solvent properties of the two are similar but toluene is less toxic and is not categorised as a carcinogen.

  1. Engineering controls

Engineering controls do not eliminate hazards; instead they isolate people from the hazard. This method involves designing and/or adding physical safety features. This could include placing a barrier between the person and the hazard, placing a guard to remove the hazard from the person, or removing the operator to a remote location away from the hazard.

  1. Administrative controls

These controls change the way people work and include procedure changes, employee training and installation of signs and warning labels. They do not remove the hazard but limit or prevent people’s exposure.

  1. Personal Protective Equipment (PPE)

PPE, including hard hats, gloves, respirators, safety glasses/goggles and safety footwear, is usually seen as the last line of defence and is usually used in conjunction with one or more of the other control measures. It is the least effective means of controlling hazards because of the high potential for damage to render PPE ineffective.

The hazard hierarchy should be taken into consideration when planning controls for hazards. It is important to remember that the control selected must not eliminate one hazard while creating another.