Learning Topic 4 Contribute to hazard identification, OHS risk assessment and risk control activities
This topic should provide you with the ability to:
Report identified hazards and inadequacies in risk controls
Check the workplace for hazards using itemised checklist(s) and contribute to risk assessments
Provide input to development and implementation of control measures, with reference to the hierarchy of control
Section 4.3 Contribute to risk assessments
Hazard assessment tool or matrix
In the context of the situation, how dangerous is the hazard you have identified? For each hazard think about: Likelihood: How likely is it to happen or to be that bad?
Here is a more detailed version of the Hazard rating chart which was in topic 1: Plan and conduct work safely:
Hazard Risk Assessment Matrix
Consequence
How severely could it impact on the environment, or hurt someone, or how ill could it make someone, or how severely could it impact financially?
Very Likely
It could happen at any time
Likely
It could happen sometime
Unlikely
It could happen but very rarely
Very Unlikely
It could happen but probably never will
Catastrophic
For example, death, toxic release off-site, huge financial loss
1
1
2
3
Major
For example, extensive injury, off-site release with no detrimental effect, major financial loss
1
2
3
4
Moderate:
For example, medical treatment required, on-site release contained with outside assistance, high financial loss
2
3
4
5
Minor
For example, first aid treatment, on-site release contained, low-medium financial loss
3
4
5
6
The intersecting number shows you how important it is to do something according to the following scale:
2= High Risk: Senior Management Attention required
3 & 4= Moderate Risk: Management responsibility must be specified
5 & 6= Low Risk: Manage by routine procedures, monitor and review risks.
The vertical (side) headings of the tool represent severity. Severity means the extent of the injury or degree of harm which might be caused by a hazard. For a physical or chemical hazard, a very severe effect might include death, permanent disability or an illness such as cancer or hepatitis. Moderate severity could include a broken arm, or lacerations causing several days off work, or exposure to blood borne diseases. Minor severity could mean superficial scratches or small discomforts where only first aid is required.
The top headings of the table represent likelihood. This means assessing how likely it is that a hazard will harm someone. This likelihood will range from very likely to very unlikely. How you assess for risk will vary according to the workplace and hazards (or combinations of hazards) present. If there are a number of contributing factors this will increase the level of risk.
In your risk assessment you will need to consider:
exposure: how frequently are employees and others exposed to the hazard, how severe is the exposure and how long is the time of exposure (duration)
outcome: what are the consequences of exposure to the hazard or work task
human differences: individual employees will differ in the way a particular hazard affects them.
For example:
allergies: some workers experience allergic reactions when exposed to certain chemicals or airborne particles, or latex rubber in gloves.
equipment controls: a person’s size and strength may affect their ability to safely use fixed machinery controls. Machines designed for operation by right handed people may be awkward for left handed people to use
a changing workforce means variation in the age, experience, skill and training of employees. You will need to take these into account in assessing risks.
Prioritising risks according to severity and likelihood
By using the Risk Assessment Matrix you can rank a risk according to its seriousness by plotting the estimated severity against the estimated likelihood of an unwanted event. A simple numerical scale is used: the number 1 is a high risk rank; the number 6 is a low risk rank. This method of risk assessment relies on subjective judgements about severity and likelihood, and these may not be accurate. So it’s only suitable for assessing relatively simple tasks or work activities. When risk assessment is carried out in large, complex facilities such as oil refineries or mines, qualified OHS professionals may need to help you assess and prioritise risks.
Specialist risk assessment techniques
More complex risk assessments may be qualitative, semi-quantitative or quantitative depending on the degree of risk, the resources available and the accuracy of available data. Let’s take a look at each of these briefly.
Qualitative analysis
Qualitative analysis (the use of descriptions rather than numbers) is used:
to prioritise risks for attention/action
where the risk does not warrant the expenditure required for a fully quantitative analysis
where data is inadequate for quantitative analysis
to cover risk that is not identifiable numerically, eg nuclear war.
Semi-quantitative analysis
Is used when you need to give some relative value to risk priorities by using subjective estimates of probability and consequences.
Quantitative analysis
Is used where an estimate of the true value of the risk is needed, rather than a priority ranking. In quantitative analysis, you calculate the consequences and probability of an event. These can be either expressed as a numerical value for risk, or expressed as the probability or frequency of a particular event (hazard).
Many of the specialist techniques used in industry try to establish the probability of unwanted events. For example, the probability of dying from various causes in the UK has been estimated as follows:
risk per year of dying from a lightning strike: 0.0000001 or 1 in 10 million
risk per year of dying in a road traffic accident: 0.0001 or 1 in 10,000.
Risk assessments in large industrial facilities often set criteria for risk acceptability in terms of the probability of unwanted events. For example, a large chemical plant may wish to ensure that the risk of structural failure of a tank must be lower than 0.003 per year. If there are multiple events that would have to occur before the tank would fail, probabilities can be assigned to each one, in order to calculate the probability of the unwanted event. Modelling methods such as Fault Tree Analysis are based on this principle. Only highly qualified specialists are able to do complex risk assessments such as this.
