8.4.2 How to do a risk assessment
All hazards have the potential to cause different types and severities of harm, ranging from minor discomfort to a serious injury or death.
Some hazards such as noise and atmospheric contaminants may require scientific testing or measurement to accurately assess the risk (for example, using noise meters to measure noise levels).
Work out the amount of harm that could occur
To estimate the amount of harm that could result from each hazard you should consider the following questions:
• What type of harm could occur (e.g. muscular strain, fatigue, burns, laceration)? How severe is the harm? Could the hazard cause death, serious injuries, illness or only minor injuries requiring first aid?
• What factors could influence the severity of harm that occurs? For example, the distance someone might fall or the concentration of a particular substance will determine the level of harm that is possible. The harm may occur immediately something goes wrong (e.g. injury from a fall) or it may take time for it to become apparent (e.g. illness from long term exposure to a substance).
• How many people are exposed to the hazard and how many could be harmed (in and outside your workplace)?
• Could one failure lead to other failures? For example, could the failure of your electrical supply make any risk controls that rely on electricity ineffective?
• Could a small event escalate to a much larger event with more serious consequences? For example, a minor fire can get out of control quickly in the presence of large amounts of unnecessary combustible materials.
Work out how hazards may cause harm
In most cases, incidents occur as a result of a chain of events and a failure of one or more links in that chain. If one or more of the events can be stopped or changed, the risk may be eliminated or reduced.
One way of working out the chain of events is to determine the starting point where things begin to go wrong and then consider: ‘If this happens, what may happen next?’ This will provide a list of events that sooner or later causes harm.
In thinking about how each hazard may cause harm, you should consider:
• the effectiveness of existing control measures and whether they control all types of harm,
• how work is actually done, rather than relying on written manuals and procedures, and
• infrequent or abnormal situations, as well as how things are normally meant to occur.
Consider maintenance and cleaning, as well as breakdowns of equipment (eg computers, vehicles) and failures of health and safety controls.
Work out the likelihood of harm occurring
The likelihood that someone will be harmed can be estimated by considering the following:
• How often is the task done – does this make the harm more or less likely?
• How often are people near the hazard? How close do people get to it?
• Has it ever happened before, either in your workplace or somewhere else? How often?
You can rate the likelihood as one of the following:
• Certain to occur - expected to occur in most circumstances
• Very likely - will probably occur in most circumstances
• Possible – might occur occasionally
• Unlikely – could happen at some time
• Rare – may happen only in exceptional circumstances
The level of risk will increase as the likelihood of harm occurring and its severity increases.