Hazard Control Strategies That Eliminate Or Mitigate Hazards

Hazard Control Strategies That Eliminate Or Mitigate Hazards

Elimination and Substitution

Elimination and substitution, while most effective at reducing hazards, also tend to be the most difficult to implement in an existing process. If the process is still at the design or development stage, elimination and substitution of hazards may be inexpensive and simple to implement. For an existing process, major changes in equipment and procedures may be required to eliminate or substitute for a hazard.

These strategies are considered first because they have the potential to completely eliminate the hazard, thus greatly reducing the probability of an accident due to the hazard.

Some examples of these two strategies include:

  • Removing the source of excessive temperatures, noise, or pressure – this is “elimination.”
  • Substituting a toxic chemical with a less toxic or non-toxic chemical – this is “substitution.”

Engineering Controls

These controls focus on eliminating or reducing the actual source of the hazard, unlike other control strategies that generally focus on employee exposure to the hazard. The basic concept

behind engineering controls is that, to the extent feasible, the work environment and the job itself should be designed to eliminate hazards or reduce exposure to hazards. While this approach is called engineering controls, it does not necessarily mean that an engineer is required to design the control. Redesigning or replacing equipment or machinery may be expensive, but remember, according to the National Safety Council, the cost per medically consulted injury in 2013 was $42,000, and the cost per death was $1,450,000.

Remember: No hazard + No exposure = No accident.

Engineering controls do not necessarily have to be expensive or complicated. They can be quite simple in some cases. Engineering controls are based on the following broad strategies:

  1. If feasible, design or redesign the tools, equipment, machinery, materials and/or facility.
  2. Enclose the hazard to prevent exposure in normal operations; and
  3. If complete enclosure is not feasible, establish barriers or local ventilation to reduce exposure to the hazard in normal operations.

Some examples of this strategy include:

  • Redesigning a process to reduce exposure to a hazardous moving part;
  • Redesigning a work station to relieve physical stress and remove ergonomic hazards; or
  • Designing general ventilation with sufficient fresh outdoor air to improve indoor air quality and generally to provide a safe, healthful atmosphere.


When you cannot remove a hazard, and cannot replace it with a less hazardous alternative, the next best control is enclosure. Enclosing a hazard usually means that there is no hazard

exposure to workers during normal operations. There still will be potential exposure to workers during maintenance operations or if the enclosure system breaks down. For those situations, additional controls such as safe work practices or personal protective equipment (PPE) may be necessary to control exposure.

Some examples of enclosure designs are:

  • Complete enclosure of moving parts of machinery;
  • Complete containment of toxic liquids or gases from the beginning to end of a process;
  • Glove box operations to enclose work with dangerous microorganisms, radioisotopes, or toxic substances; and
  • Complete containment of noise, heat, or pressure producing processes with materials especially designed for those purposes.

Barriers or Local Ventilation

When the potential hazard cannot be removed, replaced, or enclosed, the next best approach is to install a barrier to the exposure or, in the case of air contaminants, local exhaust ventilation to remove the contaminant from the workplace. This engineered control involves potential exposure to the worker even in normal operations. Consequently, it should be used only in conjunction with other types of controls, such as safe work practices designed specifically for the site condition and/or PPE. Examples include:

  • ventilation hoods in laboratory work
  • machine guarding, including electronic barriers
  • isolation of a process in an area away from workers
  • baffles used as noise-absorbing barriers
  • nuclear radiation or heat shields

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