Once hazards have been identified, we must assess the level of risk. That is, we must determine how likely it is that someone could be harmed by the hazards and how serious the injury or illness could be.

First, consider an accident occurring, the:

  • Consequence (or seriousness)

    • How serious would the injury or illness be?
    • How many people are at risk?

  • Likelihood

    • Has it happened before?
    • How often might it happen?
    • When is it most likely to happen?

When estimating consequence and likelihood, also consider what risk controls are already in place.
For example, personal protective equipment may already be used, or guarding may be in place.

Also think about the way different hazards linked to an activity may interact to affect the consequence or likelihood of an accident occurring.

A risk management matrix is one way of combining consequence and likelihood to give risk level, where:

Critical risk   Immediate action required.
High risk   Senior management attention needed.
Moderate risk   Management responsibility must be specified.
Low risk   Manage by routine procedures.
Risk Matrix

Based on a combination of:

  • Consequence (or seriousness) that may be:
Insignificant  Non-injury incident. Minor effects on     biological or physical  environment.
Minor Injury or ill health requiring first aid. Moderate, short-term effects but not affecting ecosystem functions.
Moderate Injury or ill health requiring medical attention. Serious medium- term environmental effects.
Major Injury or ill health requiring hospital admission. Very serious long term impairment of ecosystem functions.
Catastrophic  Fatality or permanent disabling injury. Very serious long term impairment of ecosystem functions.

and

Likelihood (or chance) that may be:

Almost certain The event will occur on an annual basis.
Likely The event has occurred several times or more in your career.
Possible The event might occur once in your career.
Unlikely The event does occur somewhere from time to time.
Rare Heard of something like this occurring elsewhere.

This risk matrix is from the Australian Standard/New Zealand Standard 4360: Risk Management (AS/NZS 4360).