Occupational Safety, Health and Environmental Practice
This domain tests hazard awareness and the control logic behind safe systems of work: risk assessment, the hierarchy of controls, machine and electrical safety, fire response, chemical handling and waste management.
Risk assessment
Risk = likelihood × severity, scored on a 5 × 5 matrix. Controls are applied in order: eliminate, substitute, engineer (guarding, extraction, interlocks), administer (procedure, training, rotation), then PPE as the last line. PPE is never the primary control.
Machine and electrical safety
Guards must prevent access to nip points and interlocks must stop drive power when opened - never bypass them. Lockout/tagout follows isolation, lock, tag, release stored energy, verify dead, then work. Earth leakage protection trips at 30 mA; fixed installations are earthed to give a low-impedance fault path.
Fire and chemicals
Fire classes: A solids, B flammable liquids, C gases, D metals, and electrical. Water is wrong for electrical and burning liquid fires; use CO₂ or dry powder. Use an extinguisher with PASS: pull, aim, squeeze, sweep. The safety data sheet has 16 sections and gives hazards, PPE and first aid. Segregate waste at source: metal, plastic, oil, hazardous.
Health
Noise action level is 85 dB(A) over 8 hours; hearing protection is mandatory above it. Before confined-space entry, test oxygen (19.5–23.5 %) and toxic/flammable gas, then ventilate.
Worked example. A task scores likelihood 4 and severity 3, giving risk 12 - high. Work stops until an engineering control (fixed guard plus interlock) reduces likelihood to 2, giving risk 6, which is tolerable with supervision.
Traps. Listing PPE as the first control; using water on an electrical fire; entering a confined space before gas testing; treating a near miss as needing no report.