How to assess risk
If you do a good risk assessment, you will identify most kinds of incidents you need to be prepared for.
Assess risk in terms of:
- probability of it happening, and
- how much harm it would cause.
This fits on a graph like this:
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Probability of occurrence |
Very probable |
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Medium |
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Very improbable |
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Very little harm |
Medium harm |
Very serious harm |
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How much harm |
This gives a risk rating. The example below is simple because it has only three levels of harm and probability:
- Very low risk
- Medium risk
- Very high risk: requires urgent action.
In a diagram it looks like this
|
Probability of occurrence |
Very probable |
Medium risk |
High risk |
Very high risk |
|
Medium |
Low risk |
Medium risk |
High risk |
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Very improbable |
Very low risk |
Low risk |
Medium risk |
| |
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Very little harm |
Medium harm |
Very serious harm |
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How much harm |
However, most risk diagrams have five levels of probability and five levels of harm.
So the diagram looks like this:
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Very probably
(5) |
Medium risk
|
Medium to high risk |
High risk |
High/Very high risk |
Very high risk (25) |
|
High probability
(4) |
Low to medium risk |
Medium risk |
Medium to high risk |
High risk |
High/Very high |
|
Medium probability
(3) |
Low risk |
Low to medium risk |
Medium risk |
Medium to high risk |
High risk |
|
Low probability
(2) |
Low/very low risk |
Low risk |
Low to medium risk |
Medium risk |
Medium to high risk |
|
Very low probability
(1) |
Very low risk (1) |
Low/very low risk |
Low risk |
Low to medium risk |
Medium risk |
| |
Very little harm
(1) |
Little harm
(2) |
Medium harm
(3) |
Serious harm
(4) |
Very serious harm
(5) |
- How much harm could each hazard cause? Rate it from 1 to 5.
- How probable is it that each one will actually happen? Rate it from 1 to 5.
- Calculate the risk. For each one, multiply harm and probability; that is, multiply scores from lines 1 and 2 above. This tells you how much risk.
- A score of 1 indicates that the item is no risk; it either would cause no harm or won’t happen. You can ignore it.
- A score of 25 indicates that the item is extreme risk; it will cause serious harm and will definitely happen sooner or later. (In fact, it probably already has happened.) It is a top priority.
- A score of 5 – 20 indicates the level of risk. It will cause some harm and will probably happen sometime.
- Risks rated 9 or above are mid to high risks. Make sure you have something in place for each one.
- You can then use those scores to decide what to do.
Example 1
Hazard: Slippery floor resulting from liquid spills
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|
Score |
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Amount of harm: |
Very serious (Serious falls, especially elderly people) |
3 |
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Probability: |
Very probable |
5 |
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Risk level: |
Medium risk |
15 |
What to do: Mop up as much as possible, Put caution signs out until floor is dry.
Example 2
Hazard: Fatigue (Slow or incorrect responses when working on machinery could cause serious accident)
|
|
Score |
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Amount of harm: |
Serious |
4 |
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Probability: |
Low |
2 |
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Risk level: |
High risk |
8 |
What to do: Regularly rotate workers between jobs.
Example 3
Hazard: Attacked by little green men in flying saucers from Mars
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|
Score |
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Amount of harm: |
Very serious (planetary destruction) |
5 |
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Probability: |
Zero |
0 |
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Risk level: |
No risk |
0 |
What to do: Nothing.
Example 4
Hazard: Slippery stairs could cause someone to slip and fall
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|
Score |
|
Amount of harm: |
Medium (injuries) |
3 |
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Probability: |
High probability |
5 |
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Risk level: |
Medium to high risk |
15 |
What to do: Put non-slip edges on stairs.
Yes, I'm ready to go on.
No, I need to reread it.
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