Health, Safety, and Environmental Management
This domain tests hazard identification and control selection: applying the hierarchy of controls, quantifying exposure against limits, and managing high-risk work through permit systems.
Core rules
- Hierarchy of controls, most to least effective: elimination, substitution, engineering controls, administrative controls, then PPE. PPE is the last line and depends on correct fit and use.
- Risk = likelihood × severity; reduce to as low as reasonably practicable (ALARP) and record the residual risk and its owner.
- Lockout/tagout sequence: notify, shut down, isolate, lock and tag, release stored energy (gravity, thermal, hydraulic, pneumatic, electrical), then verify zero energy.
- Permit-to-work controls hot work, confined spaces and excavation. Gas testing order in a confined space: oxygen first, then flammables, then toxics; test at top, middle and bottom.
- Occupational exposure limits: 8-hour TWA and 15-minute STEL. Noise uses a 3 dB exchange rate, so each 3 dB(A) above 85 halves permissible duration.
Worked example
A worker is exposed to 90 dB(A) over an 8-hour shift, against an 85 dB(A) 8-hour limit.
- Exposure ratio = 2^((90−85)/3) = 2^1.667 ≈ 3.17.
- Permissible duration = 8/3.17 ≈ 2.5 hours.
- An 8-hour exposure is therefore roughly 317% of the limit - a serious overexposure. The correct response is an engineering control (enclose or silence the source, relocate the operator) rather than issuing hearing protection alone; PPE becomes the interim measure while the control is installed.
Traps
Reaching for PPE first; judging safety by absence of incidents last year; relying on odour to detect hydrogen sulphide; forgetting gravity or thermal stored energy in lockout; taking a single gas sample in one location.