What is Hierarchy of Controls?

| March 23, 2009

I recently had the following question e-mailed to me – “What is the “Hierarchy of Controls” [referenced in section 4.3.1 of OHSAS 18001:2007] and how do I address it in the hazard control & risk assessment procedure?”
The “hierarchy of controls” is a protocol that you use when deciding what kind of control measures you are going to use to address a particular OH&S hazard.  The rationale underlying the “hierarchy of controls” is that an organization should use more reliable control measures rather than measures that are more likely to fail. 

Elimination is considered the most relable control measure because, if a hazard is eliminated, it no longer poses a risk.  On the other hand, control measures that rely on individuals behaving in a certain way are considered less reliable. The wearing of personal protective equipment (PPE) is considered a less reliable control because it is dependent on individuals using the right PPE and wearing it correctly.

For example, lets say the “hazard” one wants to control is exposure to a chemical used in cleaning a manufacturing area that is likely to cause ill health at a certain level of exposure. 

To use the “hierarchy of controls” protocol – you would take the following steps –

  1. Explore whether the use of the chemical can be eliminated
  2. If the use of the chemical cannot be eliminated – then you would explore whether there is a substitute chemical that can be used that does not have the same potential to cause ill health
  3. If the use of the chemical cannot be eliminated and there is no suitable less toxic substitute – then one explores whether there is an appropriate engineering control  – such installation of a ventilation system that reduces the exposure
  4. If an engineering control cannot be used (or until it can be installed), then other “adiminstrative controls” such as warning signs, PPE, etc. would  need to be put in place to reduce the hazard

The use of hierarchy of controls is a reiterative process – as individual control measures are put in place, you need to go back and re-evaluate the risk to see if it has reached an acceptable level or if additional controls are still needed.

For any particular hazard, more than one control measure may be needed to address the risk.  For example, controlling the risk of exposure to a toxic chemical may require the installation of a ventilation system AND establishing a preventive maintenance program for the ventilation system AND the use of warning signs AND the use of PPE. 

© ENLAR® Compliance Services, Inc. (2009)

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Category: OHSMS Implementation, Risk Management

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