Introduction to Health and Safety at Work

6.3 
Hierarchy of risk control
When assessing the adequacy of existing controls or 
introducing new controls, a hierarchy of risk controls 
should be considered. The principles of prevention in 
the MHSW Regulations are not exactly a hierarchy, but 
must be considered alongside the usual hierarchy of risk 
controls, which is as follows:
➤
elimination
➤
substitution
➤
changing work methods/patterns
➤
reduced or limited time exposure
➤
engineering controls (e.g. isolation, insulation and 
ventilation)
➤
good 
housekeeping
➤
safe systems of work
➤
training and information
➤
personal protective equipment
➤
welfare
➤
monitoring and supervision
➤
review.
6.3.1 Elimination or substitution
This is the best and most effective way of avoiding 
a severe hazard and its associated risks. Elimination occurs 
when a process or activity is totally abandoned because 
the associated risk is too high. Substitution describes the 
use of a less hazardous form of the substance. There are 
many examples of substitution, such as the use of water-
based rather than oil-based paints, the use of asbestos 

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Introduction to Health and Safety at Work
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substitutes and the use of compressed air as a power 
source rather than electricity. Care must be taken not to 
introduce additional hazards and risks as a result of 
a substitution.
6.3.2 Changing work methods/patterns
In some cases it is possible to change the method of 
working so that exposures are reduced. For example 
use rods to clear drains instead of strong chemicals; 
use disposable hooks for holding articles being sprayed 
instead of exposing people during the cleaning of 
reusable hooks. Sometimes the pattern of work can be 
changed so that people can do things in a more nat-
ural way, for example when removing components and 
packing them consider whether people are right or left 
handed; encourage people in offi ces to take breaks from 
computer screens by getting up to photocopy, fetch fi les 
or printed documents.