Fire Protection
Procedure & Guidance
Methods of Fire Risk Assessment (Fire Safety Training)
Ref
Issue/Revision Date
19/09/2011
Review Date
19/09/2014
Version
FS- NFG056
7.0
Introduction
The purpose of this Note is to introduce Fire Safety Inspectors to some recognised methods of fire risk
assessment.
Risk Assessment
A risk assessment usually involves identifying the hazards present in any undertaking (whether arising
from work activities or from other factors, e.g., the layout or contents of the premises) and then
evaluating the extent of the risks involved, taking into account whatever precautions are already being
taken. In this Note: A hazard is something with the potential to cause harm (this can include flammable
substances, methods of work and other aspects of work organisation);
Risk is the likelihood of that harm occurring;
The extent of the risk covers the population which might be affected by a risk; i.e. the
number of people who might be exposed and the consequences for them.
Risk therefore reflects both the likelihood that harm will occur and its severity.
In the vast majority of cases it will be a relatively straightforward and simple task. Indeed there are
only three "rules" that should be borne in mind:
1.
There is no single correct way in which the assessment should be made. Put another way, the
first rule of risk assessment is that there are no rules!
2.
The methodology to be adopted should be a practical, structured and above all, a
commonsense one.
3.
Whilst the legal responsibility for carrying out the assessment normally rests with the employer,
in large or complex workplaces they are at liberty to seek the help of their own experts or, if
necessary, the help of outside consultants.
This Note in the following sections will describe four possible risk assessment methods, i.e.
•
•
•
•
The Six-Step method
The risk value matrix method
An industrial method
An algorithmic method
Fire Safety Officers or Inspectors must assure the risk assessment provided by a responsible
person is a suitable and sufficient assessment of the risks to which relevant persons are exposed for
the purpose of identifying the general fire precautions they need to take to comply with the RR(FS)O
(see Article 9)
In addition to the methods listed above officers should be familiar with the Five Step Method contained
in the Fire Safety Risk Assessment series of guides published by the CLG
(www.communities.gov.uk/fire/firesafety/firesafetylaw)
Six-Step Method
This method entails a two-fold process:
1.
2.
Identifying the fire hazards (i.e. readily combustible or highly flammable materials, sources of
heat, and unsatisfactory structural features).
Assessing the fire risk (i.e. the likelihood that a fire will occur and the consequences of such a
fire on the people in the workplace).
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The overall process may be carried out in six steps:
Step 1:
Step 2:
Step 3:
Step 4:
Step 5:
Step 6:
Identify hazards,
Identify people at risk,
Remove/reduce hazards,
Assign the risk category,
Decide if existing fire safety arrangements are OK or need improving,
Record findings.
Step 1: Identification of Hazards
Identifying hazards entails noting readily combustible materials or highly flammable substances.
These would include such things as paints and thinners, flammable solvents, solvent-based
adhesives, flammable gases, some plastic foams, large areas of bare hardboard, highly flammable
and/or reactive chemicals etc.
It also entails noting sources of heat such as flames or sparks from processes, sources of frictional
heat, ovens, kilns, incinerators, oil or gas fired equipment or heaters, matches and lighters, ducts or
flues, light bulbs close to flammable materials, electrical wander leads, any electrical equipment, faulty
wiring, portable heaters, etc.
Structural features that would constitute hazards by promoting the rapid spread of fire should therefore
be identified. These would include such things as ducts and flues, unstopped holes that have been cut
into fire resisting walls for the provision of services such as cables and pipe work, large areas of
hardboard, chipboard, or blockboard, uncompartmented roof spaces. Excessively long escape routes
and dead end conditions that would prejudice the means of escape should also be identified.
Step 2: Identification of People at Risk
In identifying people who would be especially at risk in a fire, consideration should be given to any
who are asleep, any who are present in large numbers, any who are unfamiliar with the layout of the
premises and/or the exit routes, those who may be exposed to a particular or specific fire risk, those
who have impairments such as sight, hearing, or mobility and young people or children.
Also taken into consideration should be any people who would be unable to react quickly enough or
are unaware of the danger of fire because they are in remote areas, because they have learning
difficulties, or because they are outside contractors who are unaware of the fire risks.
Step 3: Removal/Reduction of Hazards
The removal or reduction of hazards entailed in this stage of the risk assessment can have enormous
benefits insofar as, at the end of the process, it will have produced a much safer environment.
For each of the hazards that have been identified in step 1, the question should be asked, "could it be
removed, reduced, replaced, separated, protected, repaired, or cleaned?"
For example the removal of excessive amounts of combustibles, the reduction in the areas of
combustible wall linings, replacement of tungsten filament bulbs with fluorescent light fittings and
solvent based adhesives being replaced with water-based ones, separating sources of heat from
combustibles, protecting electrical equipment with thermostats, repairing damaged electrical flexes
and damaged furniture, cleaning dirty flues and ducts.
At this stage it should be decided whether any of these removals or reductions are to be undertaken
immediately, in the medium term, or in the long term.
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Step 4: Assignment of Risk Category
On completion of step three, depending upon what hazards still remain it should be possible to assign
a risk category to the workplace or, more likely, to individual parts of it.
The risk categories could be 'Low', 'Normal' and 'High': Low: There is hardly any risk from fire, few combustibles materials, no highly flammable
substances, and virtually no sources of heat.
Normal: There are sufficient quantities of combustible materials and sources of heat to be
of greater than low fire risk but that a fire would be likely to remain confined, or to spread
but slowly.
High:
There is a serious risk to life from fire, or there are substantial quantities of
combustible materials, or there are any highly flammable substances, or there exists the
likelihood of the rapid spread of fire, heat or smoke.
Step 5: Adequacy or Improvement of Fire Precautions
In this step, it is necessary to decide whether the existing fire safety measures are adequate or are in
need of improvement. Possible improvements could include such steps as:
•
•
•
•
•
•
•
•
•
•

Reduction of evacuation times/escape route lengths,
Protection of escape routes,
Provision of additional escape routes,
Installation of a fire alarm system or more fire alarm call points,
Provision of more fire signs,
Installation of fire detection systems,
Installation of a sprinkler system,
Installation of an emergency lighting system,
Institution of better programmes of fire safety training,
Provision of, or increasing the number of fire extinguishers
Provision of regular training and practice of fire and evacuation drills.
Step 6: Recording Findings
This simply entails recording the findings of the fire risk assessment, and should include the significant
hazards found to be present, the details of any staff who are especially at risk, and the date on which
the assessment was made.
Risk Value Matrix Method
Unlike the Six-Step method, this method attempts to put the risk assessment onto a quantitative basis.
However, it cannot be too strongly stressed that the numbers involved are purely relative, and
therefore they have no absolute significance whatsoever.
Whilst all risks are made up of two elements (i.e. the probability that an event will occur and the
harmful or unwanted consequences of that occurrence), the relative contributions that these two
elements make to the risk may vary considerably.
To give an everyday example of this point, consider two gambling risks - the tossing of a coin to
decide the winner of a wager, and the playing of Russian roulette. In each case the unwanted or
harmful consequence is losing the gamble. In the first case the probability of losing is 1 in 2, whereas
in the second case it is only 1 in 6 - three times less likely. However, the consequences of losing are
hugely different; the loss of cash in one case and the loss of a life in the other.
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For the purposes of this method, the probability that a fire event will occur is defined as the fire risk,
and the harm that would result from that event as the fire hazard.
Remembering that the two elements of risk are the fire hazard and the fire risk, it would be reasonable
to call the overall risk the 'Risk Value' defined by the simple formula:
Risk Value = Fire Hazard x Fire Risk
In order to numerically measure the risk value, it is necessary to express the fire hazard and the fire
risk by assigning values to each of the two elements. The size of the risk value then becomes the
basis for categorising the workplace as being of high, normal, or low risk.
This is easily done if the fire hazards are classified by describing them as being between negligible
and very severe, and by assigning a numerical value to each description.
Similarly, the fire risks may be classified by describing them as being between unlikely to very likely,
and by assigning a numerical value to each of these descriptions.
Fire Hazard
Negligible
Slight
Moderate
Severe
Very Severe
Value
1
2
3
4
5
Fire Risk
Unlikely
Possible
Quite possible
Likely
Very likely
FIRERISK
If the risk value formula is applied to all possible combinations of fire hazard values and fire risk values
a set of twenty five numbers is available for the risk values, which could then be displayed as a two
dimensional grid which is called a 'Risk Value Matrix' - an example of which is shown in Figure 1.
Figure 1: 5 x 5 Risk Value Matrix
1
2
3
4
5
6
FIRE HAZARD
1 2 3 4 5
1 2 3 4 5
2 4 6 8 10
3 6 9 12 15
4 8 12 16 20
5 10 15 20 25
6 12 18 24 30
6
6
12
18
24
30
36
Risk Category
Low
Normal
High
There is no particular reason for having illustrated this
method by using a 5 x 5 matrix; it could just as well
have been a 6 x 6 matrix, or an unsymmetrical matrix
such as, for example, a 6 x 4 matrix. To create a 6 x 6 matrix all that is needed is to add the
description catastrophic to the fire hazard classification, and add the description of almost certain to
the fire risk classification; the resulting matrix is shown in figure 2
The various levels of severity of the fire hazard - negligible, slight etc - could, more specifically, be
quantified in terms of the degree of harm to people, the extent of property damage, the duration of
business interruption, or the amount of financial loss.
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FIRERISK
Figure 2: 6 x 6 Risk Value Matrix
5
4
3
2
1
FIRE HAZARD
5 4 3 2 1
25 20 15 10 5
20 16 12 8 4
15 12 9 6 3
10 8 6 4 2
5 4 3 2 1
Risk Category
Low
Normal
High
The final task in this method is to decide the ranges of the risk values that will correspond to the three
categories of risk. On the assumption that the majority of work places would be of normal risk, with
very few of low risk, and perhaps slightly more of high risk, a 5 x 5 matrix - can arbitrarily, assign low
risk to values of 1-2, normal risk to values of 3-15, and high risk to values of 16-25.
An Industrial Method
This is in essence a variant of the risk value matrix method, although the terminology is slightly
different. The classification table is drawn up in terms of the frequency of an unwanted event (hazard,
defect,) and the harm that it would cause were it to happen, and these could be given numerical
values of X and Y respectively. An example of such a classification is shown in Table 1.
Table 1
Frequency
Value (X)
Harm
Value (Y)
Improbable
1
Trivial Injury
1
Possible
2
Minor Injury
2
Occasional
3
One Major Injury
3
Frequent
4
Several Major Injuries
4
Regular
5
One Death
5
Common
6
Multiple Deaths
6
For each of the unwanted events (hazards, defects), it is necessary to calculate the risk factor which is
simply the mathematical product of X and Y (X multiplied by Y), i.e.
Risk Factor = XY
Clearly for the 6 x 6 classification table, the maximum value of the risk factor will be 36 (6 x 6) the risk
factor value of any given unwanted event can then be expressed as a percentage of this maximum
value. For example, a risk factor value of 1 would be 100 x 1/36 = 2.8% of the maximum. (For a 5 x 5
matrix, the maximum risk factor value is 25 (5 x 5) and a risk factor value of 1 would be 100 x 1/25 =
4% of the maximum).
For example one for the production area, one for the office, one for the canteen would produce ∑(XY)
The resultant figure is known as the risk rating for the area. It may be expressed mathematically by
the relationship:
Risk Rating =∑ (XY) x 2.8/n
It is then necessary to determine what ranges of values of the risk rating would indicate that the area
in question should be assigned a risk category of low, normal, or high. Possible ranges are those
shown in Table 2.
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Table 2
Risk Rating
Risk Category
Less than 10%
Low
10% to 50%
Normal
Greater than 50%
High
Algorithmic Method
An algorithm is a two dimensional diagrammatic representation of the steps to be undertaken in order
to make a decision, solve a problem, or carry out a process. In short, it is a flowchart. An example of
the type of risk assessment algorithm that might be used is shown in Table 3.
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Table 3
A Fire Risk Assessment Algorithm
1 Can most flammable
Yes - Remove No - Go
materials be removed? flammables
to 2
2 Can the most likely
Yes - Separate No - Go
ignition source be
and go back to to 3
separated from the
1
flammable materials?
3 Are there easily ignited Yes - Go to 4 No - Go
materials or ones which
to 9
would give rapid
fire/smoke spread?
4 Are they throughout the Yes - Go to 7 No - Go
workplace?
to 5
5 Is each containing area Yes - go to 6 No - Go
separated from the rest
to 7
of workplace by 1 hour
resistance?
6 Do the separated areas Yes - Go to 7 No - Go
exceed 10% of the
to 8
workplace area?
7 Do these areas have
Yes - Go to 8 No - Go
automatic suppression?
to 9
8 Will fire, heat and
Yes - Go to 11 No - Go
smoke spread rapidly
to 12
through workplace by
ducts/surfaces/
structures?
9 Any other flammable
Yes - Go to 10 No - Go
materials in the
to 13
workplace?
10 Any likely sources of
Yes - Go to 11 No - Go
ignition near these
to 8
materials?
11
HIGH RISK
12
NORMAL RISK
13
LOW RISK
Starting with box 1, the first step is to identify the most flammable material in the workplace and ask
the question: "can it be removed"? If the answer is "yes", remove it from the workplace. This process
is repeated until the point is reached where no more flammable materials may be removed.
Moving on to box 2, the most likely source of ignition is identified, the question is then asked: "can it be
separated from flammable materials"? If the answer is "yes", the separation is carried out and then
the next most likely source of ignition is identified and the question repeated. As with box 1, question
and answer process is continued until no further separations can be made.
Apart from these two steps, which constitute cyclical loops, all other steps in the algorithm form a selfexplanatory linear progression which will lead to the conclusion that the workplace, or part of it, is to
be categorised as being of high, normal or low risk.
Conclusions
Any of the four methods described in this Note may be used to carry out a fire risk assessment. None
of them is infallible and, at best, they are only semi-quantitative in nature. However, a carefully carried
out fire risk assessment produces two important benefits for the responsible person of the premises.
The premises will, as a result of the risk reduction exercise, be a safer place in which to work and visit,
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a correct assessment of the fire risk will mean that scarce financial resources will be devoted to fire
safety measures targeted only where they are really needed.
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