Introduction to Health and Safety at Work

5.9.2 Persons at risk
Employees and contractors who work full time at the 
workplace are the most obvious groups at risk and it 
will be necessary check that they are competent to per-
form their particular tasks. However, there may be other 
groups who spend time in or around the workplace. 
These include young workers, trainees, new and expect-
ant mothers, cleaners, contractor and maintenance 
workers and members of the public. Members of the 
public will include visitors, patients, students or custom-
ers as well as passers by.
The risk assessment must include any additional 
controls required due to the vulnerability of any of these 
groups, perhaps caused by inexperience or disability. 
It must also give an indication of the numbers of people 
from the different groups who come into contact with 
the hazard and the frequency of these contacts.
5.9.3 Evaluation of risk level
During most risk assessment it will be noted that some 
of the risks posed by the hazard have already been 
addressed or controlled. The purpose of the risk assess-
ment, therefore, is to reduce the remaining risk. This is 
called the 
residual risk
.
The goal of risk assessment is to reduce all residual 
risks to as low a level as reasonably practicable. In a 
relatively complex workplace, this will take time so that 
a system of ranking risk is required – the higher the risk 
level the sooner it must be addressed and controlled.

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Introduction to Health and Safety at Work
72
For most situations, a 
qualitative
risk assessment 
will be perfectly adequate. (This is certainly the case for 
NEBOSH Certifi cate candidates and is suitable for use 
during the practical assessment.) During the risk assess-
ment, a judgement is made as to whether the risk level 
is high, medium or low in terms of the risk of somebody 
being injured. This designation defi nes a timetable for 
remedial actions to be taken thereby reducing the risk. 
High-risk activities should normally be addressed in 
days, medium risks in weeks and low risks in months or 
in some cases no action will be required. It will usually be 
necessary for risk assessors to receive some training in 
risk level designation.
A 
quantitative
risk assessment attempts to quantify 
the risk level in terms of the likelihood of an incident 
and its subsequent severity. Clearly the higher the likeli-
hood and severity, the higher the risk will be. The likeli-
hood depends on such factors as the control measures 
in place, the frequency of exposure to the hazard and 
the category of person exposed to the hazard. The 
severity will depend on the magnitude of the hazard (e.g. 
voltage, toxicity, etc.). HSE suggest in HSG 65 a simple 
3
⫻
3 matrix to determine risk levels.
A risk management matrix has been developed which 
combines these two risk levels as shown below.