EPHM7320 Chap.2 Hazards, Exposure and Risk
Hazards, Exposure and Risk
Four terms with different jobs
A hazard is a potential source of harm, exposure is the route that allows it to act, harm is the possible outcome, and risk combines likelihood with consequence under stated conditions. The chapter compares immediate safety hazards with health hazards that may act gradually.
It shows why existing controls and real implementation belong inside the risk judgement and why a complete answer states the source, pathway, exposed group and evidence. These distinctions make uncertainty manageable. They prompt the assessor to ask whether measurements represent the real task, whether atypical workers or conditions were included, and whether a control changes the source, route, duration or consequence.
Risk language becomes useful only when it directs evidence collection and a proportionate preventive decision.
What this chapter covers
- 01
Hazard sources and adverse effects
- 02
Exposure routes and working conditions
- 03
Immediate safety hazards and delayed health hazards
- 04
Likelihood and consequence
- 05
Existing-control performance
- 06
Complete risk statements
Worked example · free
Separate a cleaning chemical from its exposure routes
- 3Name the source and credible exposure routes.
- 3Judge conditions and existing controls.
- 3Select higher and residual controls.
Key terms
- Hazard
- A source, condition or practice with the potential to cause injury, ill health or loss.
- Risk
- A judgement that combines the likelihood of harm with the severity of its consequence under defined conditions.
- Exposure Route
- The path by which a hazardous source can reach a person and cause an effect.
- Safety Hazard
- A condition commonly associated with immediate and potentially violent injury.
- Health Hazard
- A condition that can produce illness, sometimes after repeated exposure or a latency period.
- Adverse Effect
- An unwanted change in health, function, property or environment resulting from hazardous exposure.
Hazards, Exposure and Risk FAQ
Can the same hazard have different risk in two workplaces?
Yes. The source may be identical while access, exposure route, duration, frequency, quantity, energy, vulnerable groups and control performance differ. Risk belongs to the real task and conditions, so the assessor must explain likelihood and consequence rather than copy a label.
Why is harm not the same as a hazard?
Harm is the injury or illness that may result, while the hazard is the source or condition with potential to cause it. Back pain, for example, is an outcome; repeated force, awkward posture and constrained handling conditions are hazards that can be controlled.
Should existing controls be included in a risk judgement?
Yes, but only controls that are actually present and functioning. A procedure workers cannot follow, ventilation that is off or PPE that does not fit should not be treated as reliable protection. Implementation evidence belongs inside the assessment.
Exam move
For each practice case, make four columns: source, exposure, harm and risk evidence. Do not assign a risk level until every column contains case facts. Then add a fifth column showing which proposed control changes the source, route, likelihood or consequence. Rotate through physical, chemical, biological, ergonomic and psychosocial examples so that the method does not become tied to one hazard family.
In a chemical example, distinguish intrinsic hazardous properties from the dose, route and duration of exposure. In a noise or vibration example, identify the operating condition and time pattern that make a measurement representative. In an ergonomic example, consider force, repetition, posture, recovery and individual variation rather than naming manual work alone.
For psychosocial conditions, connect work design and organisational factors to plausible health outcomes without reducing the analysis to personal resilience. Make uncertainty visible. Mark facts supported by observation or measurement, reasonable inferences, contested accounts and unknowns. Then decide which uncertainty requires immediate precaution and which can be resolved through further evidence.
Practise sensitivity by changing one assumption at a time: exposure duration, number of people, safeguard reliability, severity or frequency. Explain whether the priority changes and why. This is more useful than memorising a risk matrix colour because it shows how the judgement depends on evidence.
For every proposed control, write a causal sentence beginning with ‘This reduces risk because…’ and identify a future measure that would test the claim. If you cannot complete the sentence, the proposal may be generic rather than matched to the exposure pathway. Compare group-level controls with measures that depend on individual behaviour, and consider vulnerable or atypically exposed workers.
In assessment answers, avoid jumping from a hazard label straight to personal protective equipment. First show the source, route, exposed population and credible harm; then justify the strongest practicable intervention. End revision with a one-page hazard profile containing task boundaries, exposure circumstances, affected people, available measurements, uncertainty, existing controls and next evidence.
Exchange the profile with a classmate or test it against a new scenario: a robust framework should still guide questions when the specific hazard changes.
